JP4480176B2 - Synthetic fiber treatment liquid and synthetic fiber treatment method - Google Patents

Description

  The present invention relates to an aqueous liquid of a treating agent for synthetic fibers (hereinafter simply referred to as a treating agent) and a method for treating synthetic fibers (hereinafter simply referred to as a treating method). It is important that synthetic fibers such as polyamide fibers and polyester fibers do not generate fluff or the like in the synthetic fibers during the yarn production process. Among them, synthetic fibers for industrial materials that are used in tire cords, belts, hoses, seat belts, airbags, etc. and require high strength in relation to such applications, are made under severe conditions of high temperature and high contact pressure. Therefore, yarn swinging, fluff and tar are likely to occur in the yarn making process, and as a result, the yarn strength is lowered. Therefore, it is particularly important to prevent such yarn swinging, fluff and tar from occurring. For this reason, the treatment agent to be attached to the synthetic fiber suppresses the occurrence of the yarn sway, fluff and tar as described above, and reduces the yarn strength even when the synthetic fiber is produced at high temperature and high contact pressure. It is required to be able to prevent this. The present invention relates to an aqueous solution of a treatment agent and a treatment method that meet such requirements.

  Conventionally, as a treating agent that imparts smoothness to synthetic fibers even under high temperature and high contact pressure, and suppresses the occurrence of fluff and the like, 1) an alkylene oxide adduct of an ester compound of a polyhydric alcohol and a hydroxymonocarboxylic acid as an essential component A treating agent containing an ester compound of an alcohol component and an carboxylic acid component having maleic acid as an essential component (see, for example, Patent Document 1), 2) a carboxylic acid component comprising a dicarboxylic acid or monocarboxylic acid having no hydroxyl group, and A treatment agent containing an ester compound with an alcohol component comprising an alkylene oxide adduct of castor oil or hydrogenated castor oil (see, for example, Patent Document 2), 3) a diol component comprising a random polymer of tetrahydrofuran and alkylene oxide, and a dicarboxylic acid Contains ester compounds with components and monocarboxylic acid components That the processing agent (for example, see Patent Document 3), 4) treating agent containing a compound having a polytetramethylene glycol residues in the molecule (for example, see Patent Document 4) it has been proposed. In addition, 5) polyvalent ester compounds, anionic surfactants, and two types of hindered phenolic antioxidants as treatment agents that give heat resistance to synthetic fibers even under high temperature and high contact pressure, and suppress the generation of tars and the like. (For example, see Patent Document 5), 6) a sulfur-containing diester compound such as dialkyl thiodipropionate, a phosphate compound, and a hindered phenol-based antioxidant (for example, see Patent Document 6) 7) A compound containing a polyvalent ester compound, an ester compound having a thioether group, a secondary sulfonate compound, an organic phosphate compound, and a hindered phenol-based antioxidant (see, for example, Patent Document 7), 8 ) Sulfur-containing diester compounds such as dialkyl thiodipropionate and two hindered phenolic oxidations Containing a stopper and a phosphate metal salt (for example, see Patent Document 8), 9) containing a polyvalent ester compound and a hindered phenolic antioxidant (for example, see Patent Document 9), 10) Those containing an aromatic ester compound, an organic carboxylic acid, and various antioxidants (see, for example, Patent Document 10) are known.

However, in these conventional treatment agents, the above-mentioned yarns, fluff and tar are prevented from occurring in the synthetic fibers produced under the severer conditions in recent years, and the decrease in the yarn strength is prevented. There is a problem of being insufficient.
JP 59-223368 A JP 63-50572 A JP-A 63-235576 JP 59-59978 A JP 59-21680 A JP-A-7-216735 JP-A-8-120563 Japanese Patent Laid-Open No. 10-325074 Japanese Patent Laid-Open No. 5-140870 Japanese Patent Application Laid-Open No. 2004-292961

  The problem to be solved by the present invention is the occurrence of yarn swaying, fluff and tar in the yarn making process even when the yarn is produced under severe conditions of high temperature and high contact pressure, such as synthetic fibers for industrial materials. It is in the place which provides the aqueous liquid and processing method of the processing agent which can suppress a fall and can prevent a thread | yarn strength fall.

  As a result, the present inventors have studied to solve the above-mentioned problems. As a result, the treatment agent is an aqueous liquid, and the treatment agent contains a smoothing agent, an emulsifier and an antistatic agent in a predetermined ratio, and the smoothing agent. It is preferable that a specific isocyanuric acid derivative is contained in a predetermined ratio as at least a part of the above, and a predetermined amount as a processing agent for a synthetic fiber filament yarn subjected to the heat treatment step with an aqueous liquid of such a processing agent. It has been found that it is correct and suitable to adhere.

  That is, the present invention is an aqueous liquid of a treating agent, wherein the treating agent comprises a smoothing agent, an emulsifier and an antistatic agent. The smoothing agent is 9 to 75% by mass of the whole, and the emulsifier is 40 to 85 of the whole. It contains 0.3% to 6% by mass of the total mass and antistatic agent, and contains 7 to 35% by mass of the following isocyanuric acid derivative as at least a part of the smoothing agent. It relates to a characteristic treatment agent.

  Smoothing agent: complete ester compound of divalent or trivalent aliphatic polyhydric alcohol and aliphatic monocarboxylic acid, complete ester compound of aliphatic monohydric alcohol and divalent or trivalent aliphatic polycarboxylic acid, 2 or One selected from a complete ester compound of a trivalent aromatic polyhydric alcohol and an aliphatic monocarboxylic acid, a complete ester compound of an aliphatic monohydric alcohol and a divalent or trivalent aromatic polycarboxylic acid, and animal and vegetable fats and oils One or two or more and the following isocyanuric acid derivatives.

  Isocyanuric acid derivative: one selected from a complete ester compound of tris (2-hydroxyethyl) isocyanuric acid and an organic monocarboxylic acid and a complete ester compound of tris (2-carboxyethyl) isocyanuric acid and a monovalent aliphatic hydroxy compound One or more.

  Emulsifier: One selected from ether type nonionic surfactant having polyoxyalkylene group in molecule, polyhydric alcohol partial ester type nonionic surfactant and polyoxyalkylene polyhydric alcohol fatty acid ester type nonionic surfactant Or two or more.

  Antistatic agent: C4-C26 aliphatic mono- or dialkyl phosphate metal salt, C4-C26 polyoxyalkylene aliphatic mono- or dialkyl phosphate metal salt, C4-C26 aliphatic mono Or one or two or more selected from dialkyl phosphate organic amine salts and polyoxyalkylene aliphatic mono- or dialkyl phosphate organic amine salts having 4 to 26 carbon atoms.

  Moreover, this invention is made to adhere the aqueous liquid of the processing agent which concerns on said this invention so that it may become 0.1-3 mass% as a processing agent with respect to the synthetic fiber filament yarn used for a heat treatment process. Related to the method.

  First, the aqueous liquid of the treatment agent according to the present invention will be described. In the aqueous solution of the treatment agent according to the present invention, the treatment agent comprises a smoothing agent, an emulsifier and an antistatic agent, and contains a specific isocyanuric acid derivative as at least a part of the smoothing agent.

  In the aqueous liquid of the treating agent according to the present invention, the isocyanuric acid derivative used for the smoothing agent of the treating agent is a complete ester compound of tris (2-hydroxyethyl) isocyanuric acid and an organic monocarboxylic acid and tris (2-carboxyethyl). One or two or more selected from perfect ester compounds of isocyanuric acid and a monovalent aliphatic hydroxy compound.

  In the isocyanuric acid derivative used for the treating agent smoothing agent, the organic monocarboxylic acid used as the raw material is 1) acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, capric acid, undecanoic acid, lauric acid, C2-C22 aliphatic monocarboxylic acids such as tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, stearic acid, palmitoleic acid, oleic acid, isooctanoic acid, isohexadecanoic acid, isooctadecanoic acid, etc., 2) benzoic acid, Aromatic monocarboxylic acids such as 3,5-bis (1,1-dimethylethyl) -4-hydroxybenzenepropionic acid, 3) malonic acid, maleic acid, itaconic acid, adipic acid, sebacic acid, pentadecenyl succinate Fats of C3-C22 aliphatic dicarboxylic acids such as acids and monovalent aliphatic hydroxy compounds Monoester monocarboxylic acid, 4) aliphatic monoester monoaromatic carboxylic acid of aromatic dicarboxylic acid having 8 to 22 carbon atoms such as phthalic acid, isophthalic acid, terephthalic acid and the like and monovalent aliphatic hydroxy compound, 5) Sulfur-containing aliphatic monoester monocarboxylic acids of sulfur-containing aliphatic dicarboxylic acids having 3 to 22 carbon atoms such as thiodipropionic acid, thiodioctanoic acid, thiodilauric acid and thiodistearic acid and monovalent aliphatic hydroxy compounds Of these, aliphatic monocarboxylic acids having 2 to 22 carbon atoms are preferred, and aliphatic monocarboxylic acids having 3 to 18 carbon atoms are more preferred.

  Moreover, in the isocyanuric acid derivative used for the smoothing agent of the treating agent, the monovalent aliphatic hydroxy compound used as the raw material is 1) butyl alcohol, pentyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, decyl alcohol, C1-26 aliphatic monoalcohols such as undecyl alcohol, dodecyl alcohol, tridecyl alcohol, 2-methyl-pentyl alcohol, 2-ethyl-hexyl alcohol, 2-propyl-heptyl alcohol, 2-butyl-octyl alcohol 2) Aliphatic monoesters of aliphatic polyhydric alcohols such as 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, glycerin, trimethylolpropane, sorbitan and organic monocarboxylic acids Although Rumonooru the like, among which aliphatic monoalcohol having a carbon number of 1 to 26, and more preferably an aliphatic monoalcohol having 4 to 18 carbon atoms.

  Any of the isocyanuric acid derivatives used for the treating agent smoothing agent can be synthesized by a known method. For example, the complete ester compound of tris (2-hydroxyethyl) isocyanuric acid and organic monocarboxylic acid is 3 to 5 mol of organic monocarboxylic acid with respect to 1 mol of tris (2-hydroxyethyl) isocyanuric acid which is an alcohol component. Used to add acid compounds such as sulfuric acid and dehydrate and esterify while heating, or add basic compounds such as pyridine and esterify while heating in an inert solvent such as chloroform. it can.

  Further, for example, a complete ester compound of tris (2-carboxyethyl) isocyanuric acid and a monovalent aliphatic hydroxy compound is monovalent aliphatic with respect to 1 mol of tris (2-carboxyethyl) isocyanuric acid which is an acid component. Add 3 to 5 moles of hydroxy compound, add acidic compound such as sulfuric acid, dehydrate and esterify while heating, add basic compound such as pyridine and warm in inert solvent such as chloroform. However, it can be synthesized by a reaction of esterification.

  In the aqueous liquid of the treatment agent according to the present invention, the smoothing agent other than the isocyanuric acid derivative used for the treatment agent is 1) a divalent or trivalent fat such as 1,6-hexanediol didecanoate, trimethylolpropane monooleate dilaurate, etc. Ester compounds of aliphatic polyhydric alcohols and aliphatic monocarboxylic acids, 2) aliphatic monohydric alcohols such as dilauryl adipate, dioleyl azelate, trioctyl trimellitate and the like, and divalent or trivalent aliphatic polyvalent carboxylic acids Complete ester compound with acid, 3) Complete ester compound of divalent or trivalent aromatic polyhydric alcohol such as bisphenol A dilaurate and aliphatic monocarboxylic acid, 4) Diisostearyl isophthalate, trioctyl trimellitate, etc. Esterification of aliphatic monohydric alcohol with divalent or trivalent aromatic polycarboxylic acid Things, 5) coconut oil, rapeseed oil, sunflower oil, soybean oil, castor oil, sesame oil, fish oils, animal and vegetable fats and oils beef tallow, or 1) to 5) is one or more selected from.

  In the aqueous liquid of the treating agent according to the present invention, the emulsifier to be used for the treating agent is 1) polyoxyalkylene octyl ether, polyoxyalkylene octyl ether lauric acid ester, polyoxyalkylene nonyl phenyl ether, polyoxyalkylene oleic acid ester, Ether type nonionic surfactants having polyoxyalkylene groups in the molecule such as oxyalkylene lauryl amino ether and polyoxyalkylene lauroamide ether, 2) sorbitan monolaurate, sorbitan trioleate, sorbitol tetraoleate, glycerin monoole Art, glycerol monolaurate, diglycerol dilaurate and other polyhydric alcohol partial ester type nonionic surfactants, 3) polyoxyalkylene sorbitan trioleate, poly Polyoxyalkylenes such as xyloxyglycerin monolaurate, polyoxyalkylene bisphenol A dilaurate, polyoxyalkylene castor oil, polyoxyalkylene hydrogenated castor oil, polyoxyalkylene hydrogenated castor oil dilaurate, polyoxyalkylene hydrogenated castor oil trioctanoate Polyhydric alcohol fatty acid ester type nonionic surfactant, one or two or more selected from the above 1) to 3). Of these, polyhydric alcohol partial ester type nonionic surfactants and polyoxyalkylene polyhydric alcohol fatty acid ester type nonionic surfactants are preferred, and the polyhydric alcohol is selected from glycerin, castor oil, hydrogenated castor oil, sorbitan and sorbitol. Such as glycerin partial ester, sorbitan partial ester, sorbitol partial ester, polyoxyalkylene sorbitan ester, polyoxyalkylene sorbitol ester, polyoxyalkylene castor oil, polyoxyalkylene hydrogenated castor oil, polyoxyalkylene hydrogenated castor oil Alkyl esters are preferred.

  In the aqueous liquid of the treating agent according to the present invention, the antistatic agent used for the treating agent is octyl phosphate sodium salt, polyoxyethylene lauryl phosphate potassium salt, oleyl phosphate-triethanolamine salt, polyoxyethylene lauryl C4-C26 aliphatic mono- or dialkyl phosphate metal salt, C4-C26 polyoxyalkylene aliphatic mono- or dialkyl phosphate metal salt, such as phosphate ester-polyoxyethylene laurylamine salt, One or two or more selected from aliphatic mono- or dialkyl phosphate organic amine salts having 4 to 26 carbon atoms and polyoxyalkylene aliphatic mono- or dialkyl phosphate organic amine salts having 4 to 26 carbon atoms.

  In the aqueous solution of the treatment agent according to the present invention, the treatment agent comprises a smoothing agent, an emulsifier and an antistatic agent containing the above-described isocyanuric acid derivative, and the isocyanuric acid derivative is preferably 7 to 35% by mass, preferably Is 9 to 27% by weight of the whole, 9 to 75% by weight of the smoothing agent containing such an isocyanuric acid derivative, 40 to 85% by weight of the emulsifier, preferably 49 to 80% by weight of the whole, and an antistatic agent. The total content is 0.3 to 6% by mass, preferably 0.4 to 4% by mass.

  When adhering the aqueous liquid of the treatment agent according to the present invention to the synthetic fiber, other components such as appearance modifiers, antioxidants, heat resistance improvers, antifoaming agents, antiseptics, and rust inhibitors are purposely used. Can be used in combination, but the combined amount should be as small as possible.

  Next, the processing method according to the present invention will be described. The aqueous solution of the treatment agent according to the present invention is obtained by diluting the treatment agent as described above with water, but the treatment method according to the present invention is a synthetic fiber filament that uses the aqueous solution of the treatment agent for the heat treatment step. It is a method of adhering to the yarn so that the treatment agent is 0.1 to 3% by mass, preferably 0.5 to 1.5% by mass. Examples of the step of adhering the aqueous liquid of the treatment agent according to the present invention to the synthetic fiber include a spinning step, a drawing step, a step of simultaneously performing spinning and drawing, and the like. In addition, examples of the method for attaching the aqueous liquid of the treatment agent according to the present invention to the synthetic fiber include a roller oiling method, a guide oiling method using a metering pump, an immersion oiling method, and a spray oiling method. Furthermore, although the form which makes a processing agent adhere to a synthetic fiber is an aqueous liquid, it is preferable that the density | concentration shall be 5-30 mass% aqueous liquid of a processing agent. The aqueous liquid of the treatment agent according to the present invention is attached to the synthetic fiber filament yarn to be subjected to the heat treatment step so that the treatment agent is 0.1 to 3% by mass, preferably 0.5 to 1.5% by mass. .

  Synthetic fibers to which the treatment method according to the present invention is applied include 1) polyester fibers such as polyethylene terephthalate, polypropylene terephthalate, and polylactic acid ester, 2) polyamide fibers such as nylon 6 and nylon 66, and 3) polyacryl. 4) Polyolefin fibers such as modacrylic, 4) Polyolefin fibers such as polyethylene and polypropylene, 5) Polyurethane fibers, etc., and the type and use thereof are not limited, but high temperature and high contact pressure are severe in the yarn production process. The effect is high when applied to synthetic fibers for industrial materials exposed to conditions, and the effect is particularly high when applied to polyester fibers or polyamide fibers.

  In the present invention described above, even when the yarn is produced under severe conditions of high temperature and high contact pressure, such as synthetic fibers for industrial materials, the occurrence of yarn sway, fluff and tar in the yarn production process is suppressed. There is an effect that a decrease in yarn strength can be prevented.

  Hereinafter, in order to make the configuration and effects of the present invention more specific, examples and the like will be described. However, the present invention is not limited to these examples. In the following Examples and Comparative Examples, “part” means “part by mass” and “%” means “% by mass”.

Test Category 1 (Preparation of treatment agent)
-Preparation of treatment agent (P-1) 10 parts of the following isocyanuric acid derivative (K-1), 20 parts of the following smoothing agent (L-1), 10 parts of the following smoothing agent (L-2), 50 parts of the following emulsifier (E-1), 10 parts of the following emulsifier (E-2), and 1 part of the following antistatic agent (S-3) were mixed uniformly to a treating agent (P-1 ) Was prepared.
Isocyanuric acid derivative (K-1): Tris (2-hydroxyethyl) isocyanuric acid tripropionate Smoothing agent (L-1): Dioleylthiodipropionate Smoothing agent (L-2): Bisphenol A dilaurate Emulsifier (E- 1): A polyoxyalkylene aliphatic polyvalent ester compound obtained by adding 20 mol of ethylene oxide (hereinafter simply referred to as EO) to 1 mol of hydrogenated castor oil.
Emulsifier (E-2): An ester compound of 1 mol of polyoxyalkylene castor oil and 3 mol of decanoic acid obtained by adding 40 mol of EO to 1 mol of castor oil.
Antistatic agent (S-3): oleyl phosphate triethanolamine salt

-Preparation of treatment agents (P-2) to (P-68) and treatment agents (R-1) to (R-17)}
In the same manner as the treating agent (P-1), treating agents (P-2) to (P-68) and treating agents (R-1) to (R-17) were prepared. The contents of the components used for the preparation of the above treatment agents are summarized in Tables 1 to 5, and the contents of the treatment agents prepared above are summarized in Tables 6 to 14.

In Table 3,
The number average molecular weight of the compound is a value measured with HLC-8120GPC manufactured by Tosoh Corporation.

・ Test Category 2 (Adhesion and evaluation of aqueous solutions of various treatment agents on synthetic fibers)
-Adhesion of aqueous solution of each treatment agent to synthetic fiber Except when neatly applied, each treatment agent prepared in Test Category 1 and diluted water or dilute organic solvent are uniformly mixed, and 10% of the treatment agent Diluted solution. A polyethylene terephthalate chip having an intrinsic viscosity of 1.10 and a carboxyl end concentration of 15 equivalents / 10 ⁶ g is dried by a conventional method, and then spun at 295 ° C. using an extruder, discharged from a die and cooled and solidified. The prepared 10% diluted solution or the like is adhered to the yarn by a guide oiling method using a metering pump, and then converged by a guide and taken up by a take-up roll having a surface speed of 3000 m / min. The film was drawn through a drawing roll and a relaxation roll so that the total drawing ratio was 1.7 times, and a 1670 decitex 192 filament drawn yarn was obtained as a 10 kg-kneaded cake.

・ Measurement of amount of treatment agent attached In accordance with JIS-L1073 (Synthetic fiber filament yarn test method), using a mixed solvent of normal hexane / ethanol (50/50 volume ratio) as an extraction solvent, adhesion of the treatment agent to synthetic fiber The amount was measured. The results are summarized in Tables 15-17.

-Evaluation of yarn swaying In the spinning process described above, the degree of swaying of the running yarn generated on the drawing roll was visually observed and evaluated according to the following criteria. The results are summarized in Table 15 to Table 17.
AAA: No yarn shaking occurs.
AA: Almost no yarn shaking occurs.
A: Yarn oscillation sometimes occurs.
B: Yarn sway frequently occurs.
C: Yarn swaying is intense and adjacent yarns come into contact with each other.

・ Evaluation of fluff In the above spinning process, before winding the yarn as a cake, the number of fluff per hour was measured with a fluff counting device (DT-105 manufactured by Toray Engineering Co., Ltd.) and evaluated according to the following criteria. . The results are summarized in Tables 15-17.
AAA: The number of fluffs measured is 0 AA: The number of fluffs measured is less than 1 (however, 0 is not included)
A: The number of fluffs measured is 1-2 B: The number of fluffs measured is 3-9 C: The number of fluffs measured is 10 or more

Evaluation of tar prevention property The test yarn collected from the cake obtained above is wound around a hot roller having an initial tension of 1 kg and a yarn speed of 500 m / min and wound at a surface temperature of 240 ° C., and 12 hours after the hot roller is generated. The amount of tar was visually observed and evaluated according to the following criteria. The results are summarized in Table 15 to Table 17.
AAA: Tar is not recognized.
AA: A slight amount of tar is observed.
A: A little tar is recognized.
B: Tar is clearly recognized.
C: A considerable amount of tar is observed.

-Evaluation of yarn strength The strength of the test yarn collected from the cake obtained above was measured with a high elongation measuring device (Shimadzu Autograph AGS-1KNG, manufactured by Shimadzu Corporation), and evaluated according to the following criteria. The results are summarized in Table 15 to Table 17.
AAA: The measured yarn strength is 8.0 cN / dtex or more AA: The measured yarn strength is 7.8 or more and less than 8.0 cN / dtex A: The measured yarn strength is 7.4 or more and 7.8 cN Less than / dtex B: The measured yarn strength is 7.0 or more and less than 7.4 cN / dtex C: The measured yarn strength is less than 7.0 cN / dtex

In Tables 15-17,
The organic solvent of the organic solvent solution in the column of application form is normal paraffin having a viscosity at 40 ° C. of 2.0 × 10 ⁻⁶ m ² / s.

Claims (7)

An aqueous solution of synthetic fiber-processing agent, synthetic fiber-processing agent, lubricating agents below are those consisting of emulsifiers and antistatic agents, 9-75% by weight of the total lubricating agents, of the total emulsifier 40 to 85 wt% and antistatic agent in a proportion of 0.3 to 6 wt% of the total, and it shall be contained 7 to 35 wt% of the total isocyanuric acid derivative of the following as at least a part of the lubricating agents aqueous solution of synthetic fiber-processing agent characterized and Dearuko.
Smoothing agent: Complete ester compound of a divalent or trivalent aliphatic polyhydric alcohol and an aliphatic monocarboxylic acid, Complete ester compound of an aliphatic monohydric alcohol and a divalent or trivalent aliphatic polycarboxylic acid, 2 or One selected from a complete ester compound of a trivalent aromatic polyhydric alcohol and an aliphatic monocarboxylic acid, a complete ester compound of an aliphatic monohydric alcohol and a divalent or trivalent aromatic polycarboxylic acid, and animal and vegetable oils and fats. One or two or more and the following isocyanuric acid derivatives.
Isocyanuric acid derivative: one selected from a complete ester compound of tris (2-hydroxyethyl) isocyanuric acid and an organic monocarboxylic acid and a complete ester compound of tris (2-carboxyethyl) isocyanuric acid and a monovalent aliphatic hydroxy compound One or more.
Emulsifier: One selected from an ether type nonionic surfactant having a polyoxyalkylene group in the molecule, a polyhydric alcohol partial ester type nonionic surfactant, and a polyoxyalkylene polyhydric alcohol fatty acid ester type nonionic surfactant Or two or more.
Antistatic agent: C4-C26 aliphatic mono- or dialkyl phosphate metal salt, C4-C26 polyoxyalkylene aliphatic mono- or dialkyl phosphate metal salt, C4-C26 aliphatic mono Or one or two or more selected from dialkyl phosphate organic amine salts and polyoxyalkylene aliphatic mono- or dialkyl phosphate organic amine salts having 4 to 26 carbon atoms. Organic monocarboxylic acid is an aliphatic monocarboxylic acid having 2 to 22 carbon atoms, also monovalent aliphatic hydroxy compound processing synthetic fibers of the mounting according to claim 1 Symbol is an aliphatic monoalcohol of 1 to 26 carbon atoms Aqueous solution of the agent. The emulsifier is one or more selected from a polyhydric alcohol partial ester type nonionic surfactant and a polyoxyalkylene polyhydric alcohol fatty acid ester type nonionic surfactant, and the polyhydric alcohol is glycerin, The aqueous liquid of the treating agent for synthetic fibers according to claim 1 or 2, which is selected from castor oil, hydrogenated castor oil, sorbitan and sorbitol . Claim 1-0 as an aqueous solution of synthetic fiber-processing agent against the synthetic fiber filament yarns subjected to a heat treatment process for synthetic fibers treatment agent of any one of claim wherein the 3. A method for treating synthetic fiber, comprising adhering to 1 to 3 mass%. Synthesis of claim 4, wherein the adhering to respect the synthetic fiber filament yarn to provide a 5 to 30% by mass aqueous liquid-synthetic fiber-processing agent to a heat treatment process becomes 0.1-3% by mass synthetic fiber-processing agent Fiber processing method. The synthetic fiber processing method according to claim 4 or 5 , wherein the synthetic fiber is a synthetic fiber for industrial materials. The synthetic fiber for industrial materials is a polyester fiber or a polyamide fiber, The method for treating a synthetic fiber according to any one of claims 4 to 6 .