EP4159913A1

EP4159913A1 - Aqueous solution of synthetic fiber treatment agent, and method for manufacturing synthetic fibers

Info

Publication number: EP4159913A1
Application number: EP21821920.2A
Authority: EP
Inventors: Suguru Murakami; Eri TSUBOTA; Hisanori Murata
Original assignee: Takemoto Oil and Fat Co Ltd
Current assignee: Takemoto Oil and Fat Co Ltd
Priority date: 2020-06-11
Filing date: 2021-06-04
Publication date: 2023-04-05
Also published as: CN113728137B; KR20220092635A; KR102460480B1; CN113728137A; EP4159913A4

Abstract

The present invention addresses the problem of providing an aqueous solution of a synthetic fiber treatment agent that has excellent ingredient retention properties on fibers and that has excellent low-temperature handling properties. The present invention is an aqueous solution of a synthetic fiber treatment agent comprising a smoothing agent, a nonionic surfactant and an ionic surfactant, and is characterized by: the smoothing agent comprising a specific ester A1 and optionally a specific ester A2; the smoothing agent containing a ratio of 40-100 mass% of the ester A1; the ester A1 making up a ratio of 50-100 mass% when the total content ratio of the ester A1 and the ester A2 is 100 mass%; and the viscosity of the synthetic fiber treatment agent at 30°C being 40-150mm<sup>2</sup>/s.

Description

TECHNICAL FIELD

The present invention relates to an aqueous liquid of synthetic fiber treatment agent that is excellent in ingredient retention properties on fibers and excellent in low-temperature handling properties and to a method for manufacturing a synthetic fiber that includes the step of adhering the aqueous liquid of synthetic fiber treatment agent to a synthetic fiber.

BACKGROUND ART

Generally, in a spinning step of synthetic fibers, a treatment of adhering a synthetic fiber treatment agent to the surfaces of filament yarn threads of the synthetic fibers is performed at times from a standpoint of reducing friction and reducing yarn breakage or other damage of the fibers. Modes of the adhesion treatment include that in which the synthetic fiber treatment agent is diluted with water (emulsion oiling) and that in which the synthetic fiber treatment agent is applied upon diluting with a diluting agent such as a low-viscosity mineral oil or applied as it is without being diluted (straight oiling).
Conventionally, emulsions of synthetic fiber treatment agents disclosed in Patent Documents 1 and 2 are known. Patent Document 1 discloses an emulsion containing a synthetic fiber treatment agent that contains lauryl isostearate, a smoothing agent, such as a mineral oil, and a surfactant, such as an EO adduct of oleyl alcohol. Patent Document 2 discloses an emulsion containing a synthetic fiber treatment agent that contains a glycerin ester compound and a branched ester compound.

PRIOR ART LITERATURE

PATENT LITERATURE

Patent Document 1: Japanese Laid-Open Patent Publication No. 2006-70375
Patent Document 2: International Publication No. WO 2014/156318

SUMMARY OF THE INVENTION

PROBLEMS THAT THE INVENTION IS TO SOLVE

However, with such conventional emulsions of synthetic fiber treatment agent, ingredient retention properties on fibers and handling properties at low temperature are insufficient.
The present invention has been made in view of such circumstances and an object thereof is to provide an aqueous liquid of synthetic fiber treatment agent that is excellent in ingredient retention properties on fibers and excellent in low-temperature handling properties. It is also an object of the present invention to provide a method for manufacturing a synthetic fiber that includes the step of adhering this aqueous liquid of synthetic fiber treatment agent to a synthetic fiber.

MEANS FOR SOLVING THE PROBLEMS

As a result of performing research toward solving the above problem, the inventors of the present invention found that it is truly suitable for a specific ester compound as a smoothing agent and surfactants to be contained in an aqueous liquid of synthetic fiber treatment agent and a kinematic viscosity at 30°C of the synthetic fiber treatment agent to be of a specific range.
An aqueous liquid of synthetic fiber treatment agent for solving the above problem contains a smoothing agent, a nonionic surfactant, and an ionic surfactant and is characterized in that the smoothing agent contains an ester A1 represented by Chemical Formula 1 shown below and optionally an ester A2 represented by Chemical Formula 2 shown below, the ester A1 is contained in the smoothing agent at a ratio of 40% to 100% by mass, the ester A1 is contained at a ratio of 50% to 100% by mass if the sum of the contents of the ester A1 and the ester A2 in the aqueous liquid of synthetic fiber treatment agent is taken as 100% by mass, and the synthetic fiber treatment agent has a kinematic viscosity at 30°C of 40 to 150 mm²/s.
(In Chemical Formula 1,

R¹ is a saturated hydrocarbon group with 7 to 23 carbon atoms or an unsaturated hydrocarbon group with 7 to 23 carbon atoms, and
R² is a saturated hydrocarbon group with 8 to 24 carbon atoms or an unsaturated hydrocarbon group with 8 to 24 carbon atoms.

¹

²

R³ is a saturated hydrocarbon group with 7 to 23 carbon atoms or an unsaturated hydrocarbon group with 7 to 23 carbon atoms, and
R⁴ is a saturated hydrocarbon group with 8 to 24 carbon atoms or an unsaturated hydrocarbon group with 8 to 24 carbon atoms.

³

⁴

Preferably, the aqueous liquid of synthetic fiber treatment agent has a cooling cloud point of not more than 10°C.
Preferably, the aqueous liquid of synthetic fiber treatment agent further contains an antioxidant agent, and the antioxidant agent is contained in the aqueous liquid of synthetic fiber treatment agent at a ratio of 0.01 % to 0.5% by mass if the sum of the contents of the smoothing agent, the nonionic surfactant, the ionic surfactant, and the antioxidant agent in the aqueous liquid of synthetic fiber treatment agent is taken as 100% by mass.
Preferably with the aqueous liquid of synthetic fiber treatment agent, in the Chemical Formula 1, the number of carbon atoms of R¹ is 7 to 17 and the number of carbon atoms of R² is 8 to 18 and, in the Chemical Formula 2, the number of carbon atoms of R³ is 7 to 17 and the number of carbon atoms of R⁴ is 8 to 18.
A method for manufacturing a synthetic fiber for solving the above problem is characterized by including the step of adhering the aqueous liquid of synthetic fiber treatment agent to a synthetic fiber.

EFFECTS OF THE INVENTION

The aqueous liquid of synthetic fiber treatment agent of the present invention is excellent in ingredient retention properties on fibers and excellent in low-temperature handling properties.

MODES FOR CARRYING OUT THE INVENTION

(First Embodiment)

First, a first embodiment that embodies an aqueous liquid of synthetic fiber treatment agent according to the present invention (also referred to hereinafter as aqueous liquid) will now be described. The aqueous liquid of the present embodiment contains water and a synthetic fiber treatment agent (referred to hereinafter as treatment agent), which contains a smoothing agent, a nonionic surfactant, and an ionic surfactant. The treatment agent may further contain an antioxidant agent.
The smoothing agent used in the present embodiment contains an ester A1 represented by Chemical Formula 3 shown below.
(In Chemical Formula 3,

¹

²

One type of such esters A1 may be used alone or two or more types thereof may be used in combination. Among these, a compound is preferable in which, in Chemical Formula 3, the number of carbon atoms of R¹ is 7 to 17 and the number of carbon atoms of R² is 8 to 18. By specifying to be in such ranges, especially the treatment agent can be lowered in cooling cloud point and the aqueous liquid can be improved further in low-temperature handling properties.
Specific examples of the straight chain saturated hydrocarbon group that constitutes R¹ include a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, an octadecyl group, an icosyl group, a docosyl group, and a tricosyl group.
Specific examples of the saturated hydrocarbon group having a branched chain structure that constitutes R¹ include an isoheptyl group, an isooctyl group, an isononyl group, an isodecyl group, an isoundecyl group, an isododecyl group, an isotridecyl group, an isotetradecyl group, an isopentadecyl group, an isohexadecyl group, an isoheptadecyl group, an isooctadecyl group, an isoicosyl group, an isodocosyl group, and an isotricosyl group.
The unsaturated hydrocarbon group that constitutes R¹ may be an alkenyl group having one double bond as an unsaturated carbon bond or may be an alkadienyl group or alkatrienyl group having two or more double bonds. Alternatively, it may be an alkynyl group having one triple bond as the unsaturated carbon bond or may be an alkadiynyl group having two or more triple bonds. Specific examples of the straight chain unsaturated hydrocarbon group having one double bond in the hydrocarbon group include a heptenyl group, an octenyl group, a nonenyl group, a decenyl group, an undecenyl group, a dodecenyl group, a tridecenyl group, a tetradecenyl group, a pentadecenyl group, a hexadecenyl group, a heptadecenyl group, an octadecenyl group, an icosenyl group, a docosenyl group, and a tricosenyl group.
Specific examples of the unsaturated hydrocarbon group having a branched chain structure having one double bond in the hydrocarbon group that constitutes R¹ include an isoheptenyl group, an isooctenyl group, an isononenyl group, an isodecenyl group, an isoundecenyl group, an isododecenyl group, an isotridecenyl group, an isotetradecenyl group, an isopentadecenyl group, an isohexadecenyl group, an isoheptadecenyl group, an isooctadecenyl group, an isoicosenyl group, an isodocosenyl group, and an isotricosenyl group.
Specific examples of the straight chain saturated hydrocarbon group that constitutes R² include an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, an octadecyl group, an icosyl group, a docosyl group, a tricosyl group, and a tetracosyl group.
Specific examples of the saturated hydrocarbon group having a branched chain structure that constitutes R² include an isooctyl group, an isononyl group, an isodecyl group, an isoundecyl group, an isododecyl group, an isotridecyl group, an isotetradecyl group, an isopentadecyl group, an isohexadecyl group, an isoheptadecyl group, an isooctadecyl group, an isoicosyl group, an isodocosyl group, an isotricosyl group, and an isotetracosyl group.
The unsaturated hydrocarbon group that constitutes R² may be an alkenyl group having one double bond as the unsaturated carbon bond or may be an alkadienyl group or alkatrienyl group having two or more double bonds. Alternatively, it may be an alkynyl group having one triple bond as the unsaturated carbon bond or may be an alkadiynyl group having two or more triple bonds. Specific examples of the straight chain unsaturated hydrocarbon group having one double bond in the hydrocarbon group include an octenyl group, a nonenyl group, a decenyl group, an undecenyl group, a dodecenyl group, a tridecenyl group, a tetradecenyl group, a pentadecenyl group, a hexadecenyl group, a heptadecenyl group, an octadecenyl group, an icosenyl group, a docosenyl group, a tricosenyl group, and a tetracosenyl group.
Specific examples of the unsaturated hydrocarbon group having a branched chain structure having one double bond in the hydrocarbon group that constitutes R²include an isooctenyl group, an isononenyl group, an isodecenyl group, an isoundecenyl group, an isododecenyl group, an isotridecenyl group, an isotetradecenyl group, an isopentadecenyl group, an isohexadecenyl group, an isoheptadecenyl group, an isooctadecenyl group, an isoicosenyl group, an isodocosenyl group, an isotricosenyl group, and an isotetracosenyl group.
Specific examples of the ester A1 include isotridecyl oleate, lauryl isostearate, isooctyl octylate, octyl isooctylate, isotridecyl isostearate, oleyl isostearate, icosyl isostearate, and isotetracosyl oleate.
The smoothing agent used in the present embodiment optionally contains an ester A2 represented by Chemical Formula 4 shown below.
(In Chemical Formula 4,

R³ is a saturated hydrocarbon group with 7 to 23 carbon atoms or an unsaturated hydrocarbon group with 7 to 23 carbon atoms and
R⁴ is a saturated hydrocarbon group with 8 to 24 carbon atoms or an unsaturated hydrocarbon group with 8 to 24 carbon atoms.

However, R³ and R⁴ each have a straight chain structure.)
One type of such esters A2 may be used alone or two or more types thereof may be used in combination. Among these, a compound is preferable in which, in Chemical Formula 4, the number of carbon atoms of R³ is 7 to 17 and the number of carbon atoms of R⁴ is 8 to 18. By specifying to be in such ranges, especially the treatment agent can be lowered in cooling cloud point and the aqueous liquid can be improved further in low-temperature handling properties.
Specific examples of the saturated hydrocarbon group or the unsaturated hydrocarbon group that constitutes R³ or R⁴ include the straight chain ones among the examples given for the saturated hydrocarbon group or the unsaturated hydrocarbon group that constitutes R¹ or R² of Chemical Formula 3.
Specific examples of the ester A2 include oleyl octylate, lauryl oleate, stearyl erucate, and lauryl erucate.
If the sum of the contents of the ester A1 and the ester A2 in the aqueous liquid is taken as 100% by mass, the content of the ester A1 in the aqueous liquid is 50% to 100% by mass. By specifying to be in such range, the effects of the present invention can be improved. If the sum of the contents of the ester A1 and the ester A2 in the aqueous liquid is taken as 100% by mass, the content of the ester A1 in the aqueous liquid is preferably 60% to 100% by mass. By specifying to be in such range, especially the treatment agent can be lowered in cooling cloud point and the low-temperature handling properties can be improved further.
The smoothing agent described above and used in the present embodiment may be used in combination with another smoothing agent. Another smoothing agent used as appropriate may be a known one. Specific examples of the smoothing agent include known smoothing agents used in treatment agents including (1) ester compounds of an aliphatic monoalcohol and an aliphatic monocarboxylic acid and ester compounds of an aliphatic monocarboxylic acid and a (poly)oxyalkylene adduct in which an alkylene oxide with 2 to 4 carbon atoms is added to an aliphatic monoalcohol, such as butyl stearate, isobutyl laurate, and isohexacosyl stearate, (2) ester compounds of an aliphatic polyhydric alcohol and an aliphatic monocarboxylic acid, such as 1,6-hexanediol didecanoate, trimethylolpropane monooleate monolaurate, sorbitan trioleate, sorbitan monooleate, sorbitan monostearate, and glycerin monolaurate, (3) ester compounds of an aliphatic monoalcohol and an aliphatic polycarboxylic acid and ester compounds of an aliphatic polycarboxylic acid and a (poly)oxyalkylene adduct in which an alkylene oxide with 2 to 4 carbon atoms is added to an aliphatic monoalcohol, such as dilauryl adipate, dioleyl azelate, diisocetyl thiodipropionate, and bispolyoxyethylene lauryl ether adipate, (4) ester compounds of an aromatic monoalcohol and an aliphatic monocarboxylic acid and ester compounds of an aliphatic monocarboxylic acid and a (poly)oxyalkylene adduct in which an alkylene oxide with 2 to 4 carbon atoms is added to an aromatic monoalcohol, such as benzyl oleate, benzyl laurate, and polyoxypropylene benzyl stearate, (5) ester compounds of an aromatic polyhydric alcohol and an aliphatic monocarboxylic acid and ester compounds of an aliphatic monocarboxylic acid and a (poly)oxyalkylene adduct in which an alkylene oxide with 2 to 4 carbon atoms is added to an aromatic polyhydric alcohol, such as bisphenol A dilaurate and polyoxyethylene bisphenol A dilaurate, (6) ester compounds of an aliphatic monoalcohol and an aromatic polycarboxylic acid and ester compounds of an aromatic polycarboxylic acid and a (poly)oxyalkylene adduct in which an alkylene oxide with 2 to 4 carbon atoms is added to an aliphatic monoalcohol, such as bis 2-ethylhexyl phthalate, diisostearyl isophthalate, and trioctyl trimellitate, (7) natural oils and fats, such as coconut oil, rapeseed oil, sunflower oil, soybean oil, castor oil, sesame oil, fish oil, and beef tallow, and (8) mineral oils. One type of such smoothing agents may be used alone or two or more types thereof may be used in combination.
The smoothing agent contains the ester A1 at a ratio of 40% to 100% by mass. By specifying to be in such range, the effects of the present invention can be improved. The smoothing agent preferably contains the ester A1 at a ratio of 60% to 100% by mass. By specifying to be in such range, especially the treatment agent can be lowered in cooling cloud point and the low-temperature handling properties and a fluff suppression effect in postprocessing can be improved further.
The content of the smoothing agent in the treatment agent is set as appropriate and is preferably 20% to 80% by mass, more preferably 30% to 70% by mass, and even more preferably 40% to 60% by mass. By being specified to be in such ranges, smoothness of fibers can be improved.
As the nonionic surfactant used in the present embodiment, that which is known can be adopted as appropriate. Specific examples of the nonionic surfactant include (1) compounds in which an alkylene oxide with 2 to 4 carbon atoms is added to an organic acid, an organic alcohol, an organic amine, and/or an organic amide, for example, polyoxyethylene dilaurate, polyoxyethylene oleate, and polyoxyethylene dioleate and ether type nonionic surfactants, such as polyoxyethylene octyl ether, polyoxyethylene lauryl ether, polyoxyethylene lauryl ether methyl ether, polyoxyethylene polyoxypropylene lauryl ether, polyoxypropylene lauryl ether methyl ether, polyoxyethylene oleyl ether, polyoxybutylene oleyl ether, polyoxyethylene polyoxypropylene nonyl ether, polyoxypropylene nonyl ether, polyoxyethylene polyoxypropylene octyl ether, ethylene oxide adduct of 2-hexyl hexanol, polyoxyethylene 2-ethyl-1-hexyl ether, polyoxyethylene dodecyl ether, polyoxyethylene tridecyl ether, polyoxyethylene lauryl aminoether, polyoxyethylene lauramide ether, and polyoxyethylene tristyrenated phenyl ether, (2) polyoxyalkylene polyhydric alcohol fatty acid ester type nonionic surfactants, such as polyoxyalkylene sorbitan trioleate, polyoxyalkylene coconut oil, polyoxyalkylene castor oil, polyoxyalkylene hydrogenated castor oil, polyoxyalkylene hydrogenated castor oil triooctanoate, and maleic acid ester, stearic acid ester, or oleic acid ester of polyoxyalkylene hydrogenated castor oil, (3) alkyl amide type nonionic surfactants, such as stearic acid diethanolamide and diethanolamine monolauramide, and (4) polyoxyalkylene fatty acid amide type nonionic surfactants, such as polyoxyethylene diethanolamine monooleylamide, polyoxyethylene laurylamine, and polyoxyethylene beef tallow amine.
The content of the nonionic surfactant in the treatment agent is set as appropriate and is preferably 5% to 70% by mass, more preferably 15% to 60% by mass, and even more preferably 25% to 55% by mass. By being specified to be in such ranges, the effects of the present invention and stability of the aqueous liquid can be improved.
As the ionic surfactant used in the present embodiment, that which is known can be adopted as appropriate. Examples of the ionic surfactant include anionic surfactants, cationic surfactants, and amphoteric surfactants. One type of such ingredients may be used alone or two or more types thereof may be used in combination.
As the anionic surfactant used in the present embodiment, that which is known can be adopted as appropriate. Specific examples of the anionic surfactant include (1) phosphoric acid ester salts of aliphatic alcohols, such as lauryl phosphoric acid ester salts, cetyl phosphoric acid ester salts, octyl phosphoric acid ester salts, oleyl phosphoric acid ester salts, and stearyl phosphoric acid ester salts, (2) phosphoric acid ester salts of adducts of at least one alkylene oxide selected from among ethylene oxide and propylene oxide with an aliphatic alcohol, such as polyoxyethylene lauryl ether phosphoric acid ester salts, polyoxyethylene oleyl ether phosphoric acid ester salts, and polyoxyethylene stearyl ether phosphoric acid ester salts, (3) aliphatic sulfonic acid salts or aromatic sulfonic acid salts, such as lauryl sulfonic acid salts, myristyl sulfonic acid salts, cetyl sulfonic acid salts, oleyl sulfonic acid salts, stearyl sulfonic acid salts, tetradecane sulfonic acid salts, dodecylbenzene sulfonic acid salts, and secondary alkyl (C13 to 15) sulfonic acid salts, (4) sulfuric acid ester salts of aliphatic alcohols, such as lauryl sulfuric acid ester salts, oleyl sulfuric acid ester salts, and stearyl sulfuric acid ester salts, (5) sulfuric acid ester salts of adducts of at least one alkylene oxide selected from among ethylene oxide and propylene oxide with an aliphatic alcohol, such as polyoxyethylene lauryl ether sulfuric acid ester salts, polyoxyalkylene (polyoxyethylene, polyoxypropylene) lauryl ether sulfuric acid ester salts, and polyoxyethylene oleyl ether sulfuric acid ester salts, (6) sulfuric acid ester salts of fatty acids, such as castor oil fatty acid sulfuric acid ester salts, sesame oil fatty acid sulfuric acid ester salts, tall oil fatty acid sulfuric acid ester salts, soybean oil fatty acid sulfuric acid ester salts, rapeseed oil fatty acid sulfuric acid ester salts, palm oil fatty acid sulfuric acid ester salts, lard fatty acid sulfuric acid ester salts, beef tallow fatty acid sulfuric acid ester salts, and whale oil fatty acid sulfuric acid ester salts, (7) sulfuric acid ester salts of oils and fats, such as sulfuric acid ester salts of castor oil, sulfuric acid ester salts of sesame oil, sulfuric acid ester salts of tall oil, sulfuric acid ester salts of soybean oil, sulfuric acid ester salts of rapeseed oil, sulfuric acid ester salts of palm oil, sulfuric acid ester salts of lard, sulfuric acid ester salts of beef tallow, and sulfuric acid ester salts of whale oil, (8) fatty acid salts, such as lauric acid salts, oleic acid salts, and stearic acid salts, and (9) sulfosuccinic acid ester salts of aliphatic alcohols, such as dioctyl sulfosuccinic acid salts. Examples of a counterion of the anionic surfactant include alkali metal salts, such as a potassium salt and a sodium salt, an ammonium salt, and alkanolamine salts, such as triethanolamine.
As the cationic surfactant used in the present embodiment, that which is known can be adopted as appropriate. Specific examples of the cationic surfactant include lauryltrimethylammonium chloride, cetyltrimethylammonium chloride, stearyltrimethylammonium chloride, behenyltrimethylammonium chloride, and didecyldimethylammonium chloride.
As the amphoteric surfactant used in the present embodiment, that which is known can be adopted as appropriate. Specific examples of the amphoteric surfactant include a betaine type amphoteric surfactant.
The content of the ionic surfactant in the treatment agent is set as appropriate and is preferably 1% to 20% by mass, more preferably 3% to 16% by mass, and even more preferably 6% to 13% by mass. By being specified to be in such ranges, the effects of the present invention, the stability of the aqueous liquid, or antistatic properties can be improved.
The aqueous liquid of the present embodiment preferably contains an antioxidant agent. By containing an antioxidant agent, ingredient retention properties on fibers can be improved further. As the antioxidant agent used in the present embodiment, that which is known can be adopted as appropriate. Specific examples of the antioxidant agent include (1) phenol-based antioxidant agents, such as 1,3,5-tris(3',5'-di-t-butyl-4-hydroxybenzyl)isocyanuric acid, 1,3,5-tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanuric acid, 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, 2,2'-methylene-bis(4-methyl-6-t-butylphenol), 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane, and tetrakis[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane, (2) phosphite-based antioxidant agents, such as octyl diphenyl phosphite, tris nonylphenyl phosphite, and tetratridecyl-4,4'-butylidene-bis-(2-t-butyl-5-methylphenol) diphosphate, and (3) thioether-based antioxidant agents, such as 4,4'-thiobis-(6-t-butyl-3-methylphenol) and dilauryl-3,3'-thiodipropionate. One type of such antioxidant agents may be used alone or two or more types thereof may be used in combination.
Preferably, the antioxidant agent is contained in the aqueous liquid at ratio of 0.01% to 0.5% by mass if the sum of the contents of the smoothing agent, the nonionic surfactant, the ionic surfactant, and the antioxidant agent is taken as 100% by mass. By specifying to be in such range, the ingredient retention properties on fibers can be improved further.
A kinematic viscosity at 30°C of the treatment agent is specified to be 40 to 150 mm²/s. By specifying to be in such range, the effects of the present invention can be improved.
The contents of the treatment agent and water in the aqueous liquid are not restricted in particular. The content of water in the aqueous liquid is not more than 30 parts by mass, is preferably 5 to 30 parts by mass, and is more preferably 5 to 20 parts by mass if the content of the treatment agent in the aqueous liquid is taken as 100 parts by mass. By specifying to be of such ratios, the aqueous liquid can be improved in handling properties and improved in temporal stability.
The aqueous liquid has a cooling cloud point of preferably not more than 10°C, more preferably not more than 8°C, and even more preferably not more than 7°C. If the cooling cloud point of the aqueous liquid is not more than 10°C, the effects of the present invention, especially the low-temperature handling properties and the fluff suppression effect in postprocessing can be improved further. The cooling cloud point indicates the temperature at which a turbidity of a prepared aqueous liquid disappears when it is gradually increased in temperature after first being cooled gradually from ordinary temperature and made an opaque solution with turbidity by precipitation of the ingredients.

(Second Embodiment)

Next, a second embodiment that embodies a method for manufacturing a synthetic fiber according to the present invention will be described. In the method for manufacturing a synthetic fiber of the present embodiment, a synthetic fiber is manufactured by undergoing the step of adhering the aqueous liquid of the first embodiment or an emulsion obtained by further diluting the aqueous liquid with water to a synthetic fiber, for example, in a spinning or drawing step. A water content of the aqueous liquid or the emulsion that has been adhered to the synthetic fiber may be evaporated by a drying step. The synthetic fiber to be manufactured is not restricted in particular, and specific examples thereof include (1) polyethylene terephthalate, polypropylene terephthalate, polylactic acid ester, and other polyester fibers, (2) nylon 6, nylon 66, and other polyamide fibers, (3) polyacrylic, modacrylic, and other polyacrylic fibers, and (4) polyethylene, polypropylene, and other polyolefin fibers.
The amount of the treatment agent to be adhered to the synthetic fiber is not restricted in particular, and the treatment agent is preferably adhered such as to be of a ratio of 0.1% to 3% by mass (not including water) with respect to the synthetic fiber. By this arrangement, the effects of the present invention can be improved further. The method for adhering the treatment agent to the synthetic fiber is not restricted in particular, and a known method such as a roller oiling method, a guide oiling method using a metering pump, an immersion oiling method, or a spray oiling method can be adopted.
The following effects can be obtained by the aqueous liquid, the method for manufacturing a synthetic fiber, and the synthetic fiber of the above-described embodiments.

(1) The aqueous liquid of the above-described embodiments contains a specific ester compound as the smoothing agent and the surfactants and is arranged such that the kinematic viscosity at 30°C of the treatment agent is of a specific range. It is thus excellent in ingredient retention properties on fibers. In particular, since the ingredients are retained satisfactorily on fiber surfaces, functions such as suppression of fluff and yarn cutting in postprocessing can be exhibited sufficiently. Also, an effect of being excellent in low-temperature handling properties is produced. In particular, the low-temperature handling properties under a freezing environment are excellent and, for example, coagulation of ingredients during storage of the aqueous liquid can be suppressed and stability of the aqueous liquid at low temperature can be improved. Restorability in use after low temperature storage can also be improved.
(2) With the synthetic fibers of the above-described embodiments, since the treatment agent is adhered to the fiber by the aqueous liquid that is excellent in ingredient retention properties, fluff and yarn cutting in postprocessing can be suppressed.

The above-described embodiments may be modified as follows.
· Stabilizers, antistatic agents, binders, ultraviolet absorbers, and other ingredients that are ordinarily used in aqueous liquids for quality maintenance of the aqueous liquids may further be blended in the aqueous liquid of the embodiments within a range that does not impair the effects of the present invention.

EXAMPLES

Examples will now be given below to describe the features and effects of the present invention more specifically, but the present invention is not restricted to these examples. In the following description of working examples and comparative examples, parts means parts by mass and % means % by mass.

Experimental Part 1 (Preparation of aqueous liquid of synthetic fiber treatment agents) · Preparation of aqueous liquid (Example 1)

Uniform mixing of 50% of isotridecyl oleate (A1-1) as a smoothing agent, 15% of a 25 mole ethylene oxide adduct of hydrogenated castor oil (B-1), 15% of a 15 mole ethylene oxide adduct of oleic acid (B-2), and 10% of an 8 mole ethylene oxide and 2 mole propylene oxide random adduct of lauryl alcohol (B-3) as nonionic surfactants, 4.9% of a salt of a phosphoric acid ester of polyoxyethylene (2 moles) lauryl ether and potassium (C-1), 4% of a sodium secondary alkyl sulfonate (number of carbon atoms: 13 to 15) (C-2), and 1% of potassium oleate (C-3) as ionic surfactants, and 0.1% of 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane (D-1) as an antioxidant agent was performed to obtain a mixture as a treatment agent.
Further, with the treatment agent being 100 parts by mass, 11.11 parts by mass of ion exchanged water were added and mixed uniformly to prepare an aqueous liquid of Example 1 such that a water content in the aqueous liquid is 10%.
· Preparation of aqueous liquids (Examples 2 to 13 and Comparative Examples 1 to 4) Aqueous liquids of Examples 2 to 13 and Comparative Examples 1 to 4 were prepared in the same manner as in preparing the aqueous liquid of Example 1 and using the ingredients shown in Table 1. In Table 1, along with indicating the types of the respective ingredients in each treatment agent, blending ratios (%) of the respective ingredients with the ingredients (treatment agent) besides water being 100% are indicated. Also, an addition ratio (parts) of water with each treatment agent being 100 parts is indicated.
Types and contents of the smoothing agents, types and contents of the nonionic surfactants, types and contents of the ionic surfactants, and types and contents of the antioxidant agents in the treatment agents of the respective examples are as respectively indicated in the "Smoothing agent" column, the "Nonionic surfactant" column, the "Ionic surfactant" column, and the "Antioxidant agent" column of Table 1. The mass ratio of the content of the ester A1 in each smoothing agent is indicated in the "Mass ratio: Ester A1/Smoothing agent" column of Table 1 and the mass ratio of the content of the ester A1 when the sum of the contents of the ester A1 and the ester A2 being 100% is indicated in the "Mass ratio: Ester A1/(Ester A1 + Ester A2)" column of Table 1. The addition ratio (parts) of water is indicated in the "Water" column of Table 1.
The kinematic viscosity (mm²/s) at 30°C of the treatment agent excluding water of the aqueous liquid of each example is indicated in the "Kinematic viscosity (mm²/s) at 30°C of treatment agent" column of Table 1. The operation of removing water (dehydration) was performed by heating the aqueous liquid at 105°C for 2 hours. The kinematic viscosity was determined by measuring the kinematic viscosity at 30°C of the dehydrated treatment agent by a Cannon-Fenske method.
The cooling cloud point of the aqueous liquid of each example is indicated in the "Cooling cloud point (°C)" column of Table 1. The cooling cloud point was determined by sampling 10 mL of the aqueous liquid of the treatment agent in a test tube, cooling for 30 minutes in a thermostatic chamber at -10°C, thereafter placing a thermometer in the aqueous liquid of the treatment agent, leaving to stand under a room temperature condition of 20°C, and measuring the temperature (°C) at which it is visually judged that there is no turbidity.
The following are indicated in Table 1.

A1-1: isotridecyl oleate
A1-2: lauryl isostearate
A1-3: isooctyl octylate
A1-4: octyl isooctylate
A1-5: isotridecyl isostearate
A1-6: oleyl isostearate
A1-7: icosyl isostearate
A1-8: isotetracosyl oleate
A2-1: oleyl octylate
A2-2: lauryl oleate
A2-3: stearyl erucate
A2-4: lauryl erucate
a-1: rapeseed oil
a-2: mineral oil (100 Redwood seconds, 30°C)
a-3: isobutyl laurate
a-4: isohexacosyl stearate
B-1: 25 mole ethylene oxide adduct of hydrogenated castor oil
B-2: 15 mole ethylene oxide adduct of oleic acid
B-3: 8 mole ethylene oxide and 2 mole propylene oxide random adduct of lauryl alcohol
B-4: 20 mole ethylene oxide adduct of oleyl alcohol
B-5: 3 mole ethylene oxide adduct of 2-hexyl hexanol
B-6: stearic acid diethanolamide
C-1: salt of phosphoric acid ester of polyoxyethylene (2 moles: represents the number of added moles of ethylene oxide) lauryl ether and potassium
C-2: sodium secondary alkyl sulfonate (number of carbon atoms: 13 to 15)
C-3: potassium oleate
C-4: lauryl phosphoric acid ester potassium salt
C-5: lauryl sulfonic acid ester sodium salt
D-1: 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane
D-2: 1,3,5-tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanuric acid

Experimental Part 2 (Evaluation of aqueous liquids)

· Manufacture of drawn yarn

A specific amount of ion exchanged water was further added to the aqueous liquid of each example obtained as described above and mixed uniformly to prepare an emulsion with a treatment agent concentration of 10%. Chips of polyethylene terephthalate with an intrinsic viscosity of 0.64 and a titanium oxide content of 0.2% were dried by a routine method and thereafter spun into a yarn at 295°C using an extruder. After discharging from a nozzle to cool and solidify, the running yarn thread was subject to adhesion of the abovementioned emulsion at 1.0% as treatment agent with respect to the running yarn thread by a guide oiling method using a metering pump. Thereafter, bundling by a guide was performed, taking off at a speed of 1,400 m/minute by a takeoff roller heated to 90°C was performed, and then drawing to 3.2 times between the takeoff roller and a drawing roller rotating at a speed of 4,800 m/minute was performed to manufacture a drawn yarn of 83.3 decitex (75 denier) and 36 filaments. Using the manufactured drawn yarn, ingredient retention properties on fibers were evaluated as fluff and yarn cutting in postprocessing. Also, low-temperature handling properties of the aqueous liquids were evaluated by the following method. The results are shown in Table 1.

· Evaluation of postprocessing fluff

Ten packages of the drawn yarn obtained by the above method were set in a miniature warping machine that models a warping machine and were wound for 24 hours at a yarn speed of 600 m/minute under an atmosphere of 25°C × 65% RH.

· Evaluation of fluff

Immediately before this winding, the number of fluffs was measured for 4 hours with a fluff counter (trade name: DT-105, made by Toray Engineering Co., Ltd.) and postprocessing fluff was evaluated based on the following evaluation criteria. The results are shown in the "Postprocessing fluff" column of Table 1.

∘∘∘ (excellent): The number of fluffs in 4 hours was 0 to 2.
∘∘ (satisfactory): The number of fluffs in 4 hours was 3 to 5.
∘ (fair): The number of fluffs in 4 hours was 6 to 9.
× (poor): The number of fluffs in 4 hours was 10 or more.
· Evaluation of postprocessing yarn cutting

Winding was performed for 24 hours in the same way as in the evaluation of fluff. The number of times the yarn became cut during the 24 hours of winding was measured and postprocessing yarn cutting was evaluated based on the following evaluation criteria. The results are shown in the "Postprocessing yarn cutting" column of Table 1.

· Evaluation of yarn cutting

∘∘∘ (excellent): The number of times of yarn cutting in 24 hours was 0 times.
∘∘ (satisfactory): The number of times of yarn cutting in 24 hours was 1 to 2 times.
∘ (fair): The number of times of yarn cutting in 24 hours was 3 to 4 times.
× (poor): The number of fluffs in 24 hours was 5 times or more.
· Low-temperature handling properties

The low-temperature handling properties of the aqueous liquids were evaluated as coagulability and restorability. The coagulability and restorability were determined by the following methods.

. Evaluation of coagulability

From each aqueous liquid that was heated to 30°C and made uniform by stirring, 60 mL were placed in a plastic bottle with lid (inner diameter: 45 mm) of 100 mL volume and the container was sealed shut. The plastic bottle containing the aqueous liquid was left to stand for 3 days in an incubator with a temperature set to -5°C. After leaving to stand, the appearance of the aqueous liquid was judged visually and the coagulability was evaluated based on the following criteria. In regard to "fluidity" as mentioned in the following criteria, it was judged that there is fluidity if, when the plastic bottle containing the aqueous liquid was tilted to its side (90°), a portion of the aqueous liquid flowed out of the container within 30 seconds. The results are shown in the "Coagulability" column of Table 1.

∘∘∘ (excellent): There is no clouding or turbidity in appearance and there is fluidity.
∘∘ (satisfactory): There is clouding or turbidity in appearance and a portion is solidified.
∘ (fair): There is clouding or turbidity in appearance and a large portion is solidified.
× (poor): Completely coagulated and there is no fluidity.
· Evaluation of restorability

The plastic bottle containing the aqueous liquid used in the coagulability evaluation was taken from the incubator of -5°C and left to stand for 3 hours in an incubator with a temperature set to 10°C. Thereafter, the appearance of the aqueous liquid was judged visually and the restorability was evaluated based on the following criteria. The evaluation criteria of "fluidity" as mentioned in the following criteria is the same as in the criteria indicated for the Coagulability column. The results are shown in the "Restorability" column of Table 1.

∘∘∘ (excellent): There is no clouding or turbidity in appearance and there is fluidity.
∘∘ (satisfactory): There is clouding or turbidity in appearance and a portion is solidified.
∘ (fair): There is clouding or turbidity in appearance and a large portion is solidified.
× (poor): Completely coagulated and there is no fluidity.

As is clear from the results of Table 1, the aqueous liquids of the respective examples were all evaluated as being fair or better in the evaluations of fluff and yarn cutting in postprocessing and low-temperature handling properties. The present invention succeeds in obtaining aqueous liquids that are excellent in ingredient retention properties on fibers and excellent in low-temperature handling properties.

Claims

An aqueous liquid of synthetic fiber treatment agent comprising a smoothing agent, a nonionic surfactant, and an ionic surfactant, wherein the smoothing agent contains an ester A1 represented by Chemical Formula 1 shown below and optionally an ester A2 represented by Chemical Formula 2 shown below, the ester A1 is contained in the smoothing agent at a ratio of 40% to 100% by mass, the ester A1 is contained at a ratio of 50% to 100% by mass if the sum of the contents of the ester A1 and the ester A2 in the aqueous liquid of synthetic fiber treatment agent is taken as 100% by mass, the synthetic fiber treatment agent has a kinematic viscosity at 30°C of 40 to 150 mm²/s, and the aqueous liquid of synthetic fiber treatment agent contains water at a ratio of not more than 30 parts by mass if the content of the synthetic fiber treatment agent in the aqueous liquid of synthetic fiber treatment agent is taken as 100 parts by mass.
(In Chemical Formula 1,
R¹ is a saturated hydrocarbon group with 7 to 23 carbon atoms or an unsaturated hydrocarbon group with 7 to 23 carbon atoms, and

R² is a saturated hydrocarbon group with 8 to 24 carbon atoms or an unsaturated hydrocarbon group with 8 to 24 carbon atoms.

However, at least one of R¹ and R² has a branched chain structure.)

(In Chemical Formula 2,
R³ is a saturated hydrocarbon group with 7 to 23 carbon atoms or an unsaturated hydrocarbon group with 7 to 23 carbon atoms, and

R⁴ is a saturated hydrocarbon group with 8 to 24 carbon atoms or an unsaturated hydrocarbon group with 8 to 24 carbon atoms.

However, R³ and R⁴ each have a straight chain structure.)
The aqueous liquid of synthetic fiber treatment agent according to claim 1, wherein the aqueous liquid of synthetic fiber treatment agent has a cooling cloud point of not more than 10°C.
The aqueous liquid of synthetic fiber treatment agent according to claim 1 or 2, wherein the aqueous liquid of synthetic fiber treatment agent further contains an antioxidant agent, and the antioxidant agent is contained in the aqueous liquid of synthetic fiber treatment agent at a ratio of 0.01% to 0.5% by mass if the sum of the contents of the smoothing agent, the nonionic surfactant, the ionic surfactant, and the antioxidant agent in the aqueous liquid of synthetic fiber treatment agent is taken as 100% by mass.
The aqueous liquid of synthetic fiber treatment agent according to any one of claims 1 to 3, wherein, in the Chemical Formula 1, the number of carbon atoms of R¹ is 7 to 17 and the number of carbon atoms of R² is 8 to 18 and, in the Chemical Formula 2, the number of carbon atoms of R³ is 7 to 17 and the number of carbon atoms of R⁴ is 8 to 18.
A method for manufacturing a synthetic fiber comprising adhering the aqueous liquid of synthetic fiber treatment agent according to any one of claims 1 to 4 to a synthetic fiber.