WO2024075754A1

WO2024075754A1 - Synthetic fiber treatment agent and synthetic fiber

Info

Publication number: WO2024075754A1
Application number: PCT/JP2023/036139
Authority: WO
Inventors: 千尋金子; 誠服部
Original assignee: 竹本油脂株式会社
Priority date: 2022-10-05
Filing date: 2023-10-04
Publication date: 2024-04-11
Also published as: JP7333668B1; JP2024054735A

Abstract

The present invention addresses the problem of providing a synthetic fiber treatment agent that can achieve both a scum reduction effect and an improvement in the rubber adhesiveness of synthetic fibers to which the synthetic fiber treatment agent has been applied. This synthetic fiber treatment agent includes a smoothing agent and a nonionic surfactant. The smoothing agent includes a complete ester compound of a polyvalent alcohol and a monovalent fatty acid. The nonionic surfactant includes a compound (A) resulting from the esterification of a polyvalent alcohol that has a (poly)oxyalkylene group and a valence of 2 to 5, and a fatty acid (A1) that includes a monovalent unsaturated fatty acid having two or more unsaturated bonds.

Description

Treatment agent for synthetic fibers and synthetic fibers

The present invention relates to a synthetic fiber treatment agent that can improve the rubber adhesion of synthetic fibers to which the synthetic fiber treatment agent is applied and reduce scum, and to synthetic fibers to which the synthetic fiber treatment agent is applied.

2. Description of the Related Art In a synthetic fiber spinning and drawing process or the like, a treatment is sometimes carried out in which a synthetic fiber treating agent is applied to the surface of the synthetic fiber in order to improve smoothness, antistatic properties, and the like.
Conventionally, a synthetic fiber treating agent is known, as disclosed in Patent Document 1. Patent Document 1 discloses a synthetic fiber treating agent that contains a sulfonic acid compound having an alkenyl group, a sulfonic acid compound having a hydroxyalkyl group, and a sulfonic acid compound having a hydrocarbon group having a sulfo group.

JP 2021-046647 A

However, conventional synthetic fiber treatments have the problem that they are insufficient in both improving rubber adhesion and reducing scum on the synthetic fibers to which they are applied.

As a result of research aimed at solving the above problems, the present inventors have found that a treatment agent for synthetic fibers containing a predetermined smoothing agent and a nonionic surfactant is suitable.
Various aspects for solving the above problems will be described below.

The synthetic fiber treatment agent of embodiment 1 contains a smoothing agent and a nonionic surfactant, the smoothing agent contains a complete ester compound of a polyhydric alcohol and a monovalent fatty acid, and the nonionic surfactant contains a compound (A) obtained by esterifying a polyhydric alcohol having a valence of 2 to 5 and a valence of 5, which has a (poly)oxyalkylene group, and a fatty acid (A1) containing a monounsaturated fatty acid having two or more unsaturated bonds.

Aspect 2 is the synthetic fiber treatment agent according to aspect 1, in which the fatty acid (A1) contains at least one selected from a monounsaturated fatty acid having two unsaturated bonds and a monounsaturated fatty acid having three unsaturated bonds.

In a third aspect, in the agent for treating synthetic fibers according to the first or second aspect, the agent for treating synthetic fibers contains the compound (A) in an amount of 0.1% by mass or more and 20% by mass or less.
In a fourth aspect, in the treatment agent for synthetic fibers according to any one of the first to third aspects, the nonionic surfactant further comprises a compound (B) obtained by esterifying a divalent or more and pentavalent or less polyhydric alcohol having a (poly)oxyalkylene group and a fatty acid (B1) including a monounsaturated fatty acid having one unsaturated bond.

Aspect 5 is the synthetic fiber treatment agent according to aspect 4, in which the mass ratio of compound (A) to compound (B) in the synthetic fiber treatment agent is compound (A)/compound (B) = 40/60 to 5/95.

Aspect 6 is a synthetic fiber treatment agent according to aspect 4 or 5, in which the nonionic surfactant further contains a compound (C) obtained by esterifying a divalent to pentavalent polyhydric alcohol having a (poly)oxyalkylene group and a fatty acid (C1) including a monovalent saturated fatty acid, and when the total content of the compounds (A), (B), and (C) is taken as 100% by mass, the compound (A) and the compound (B) are contained in a total amount of 70% by mass or more.

In a seventh aspect, in the agent for treating synthetic fibers according to any one of the first to sixth aspects, the smoothing agent further comprises a sulfur-containing ester compound.
In an eighth aspect, the synthetic fiber treating agent according to any one of the first to seventh aspects further contains an ionic surfactant.

The synthetic fiber of aspect 9 is characterized in that the synthetic fiber treatment agent described in any one of aspects 1 to 8 is attached to the synthetic fiber.

The present invention makes it possible to improve the rubber adhesion of synthetic fibers treated with a synthetic fiber treatment agent while also reducing scum.

First Embodiment
A first embodiment of the synthetic fiber treatment agent (hereinafter, also referred to as the treatment agent) of the present invention will be described below. The treatment agent of this embodiment contains a specified smoothing agent and a nonionic surfactant. The treatment agent may further contain an ionic surfactant.

(Smoothing agent)
The smoothing agent used in the treatment agent of this embodiment is composed of a complete ester compound of a polyhydric alcohol and a monovalent fatty acid. The complete ester compound is preferably a complete ester compound of a polyhydric alcohol having a chain structure of 3 to 6 carbon atoms and a monovalent fatty acid having 8 to 24 carbon atoms.

The polyhydric alcohol preferably has a chain structure, and the chain structure may be either linear or branched. Specific examples of polyhydric alcohols include ethylene glycol, propylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2-methyl-1,2-propanediol, 1,5-pentanediol, 1,6-hexanediol, 2,5-hexanediol, 2-methyl-2,4-pentanediol, 2,3-dimethyl-2,3-butanediol, glycerin, diglycerin, 2-methyl-2-hydroxymethyl-1,3-propanediol, trimethylolpropane, pentaerythritol, and sorbitol. Among these, glycerin and trimethylolpropane are preferred.

As the monovalent fatty acid, any known fatty acid can be used as appropriate, and it may be a saturated fatty acid or an unsaturated fatty acid. In addition, it may be a straight-chain fatty acid or one having a branched-chain structure.

Specific examples of monovalent fatty acids include, for example, (1) straight-chain saturated fatty acids such as formic acid, acetic acid, propionic acid, butyric acid, valeric acid, hexanoic acid (caproic acid), octanoic acid (caprylic acid), nonanoic acid, decanoic acid (capric acid), dodecanoic acid (lauric acid), tetradecanoic acid (myristic acid), hexadecanoic acid (palmitic acid), octadecanoic acid (stearic acid), eicosanoic acid (arachidic acid), docosanoic acid (behenic acid), and tetracosanoic acid. Fatty acids, (2) branched saturated fatty acids such as 2-ethylhexanoic acid, isododecanoic acid, isotridecanoic acid, isotetradecanoic acid, isohexadecanoic acid, and isooctadecanoic acid, (3) straight-chain unsaturated fatty acids such as crotonic acid, myristoleic acid, palmitoleic acid, oleic acid, vaccenic acid, eicosenoic acid, linoleic acid, α-linolenic acid, γ-linolenic acid, and arachidonic acid, and (4) hydroxy fatty acids such as ricinoleic acid.

Specific examples of complete ester compounds include triesters of trimethylolpropane and fatty acids, such as triesters of trimethylolpropane and mixed acids (palm kernel fatty acids and vegetable oleic acid), triesters of glycerin and fatty acids, such as triesters of glycerin and mixed acids (palm kernel fatty acids and vegetable oleic acid), and natural fats and oils, such as coconut oil, rapeseed oil, rapeseed oil, sunflower oil, soybean oil, castor oil, sesame oil, palm oil, and fish oil.

These completely esterified compounds may be used alone or in combination of two or more.
In the treatment agent, the lower limit of the content ratio of the complete ester compound of polyhydric alcohol and monovalent fatty acid is preferably 15% by mass or more, more preferably 20% by mass or more, and may be 26% by mass or more, 30% by mass or more, 40% by mass or more, 50% by mass or more, or 55% by mass or more. The upper limit of the content ratio of the complete ester compound of such polyhydric alcohol and monovalent fatty acid is preferably 70% by mass or less, more preferably 60% by mass or less, and may be 55% by mass or less, 50% by mass or less, 40% by mass or less, or 30% by mass or less. By specifying the range of the content ratio, the effect of the present invention can be further improved. In addition, a range in which the above upper and lower limits are arbitrarily combined is also assumed.

The smoothing agent used in the treatment agent of this embodiment preferably further contains a sulfur-containing ester compound. By including a sulfur-containing ester compound in the smoothing agent, it is possible to further reduce scum that occurs on guides, etc., for synthetic fibers to which the treatment agent is applied.

Specific examples of sulfur-containing ester compounds include dioctyl thiodipropionate, diisolauryl thiodipropionate, dilauryl thiodipropionate, diisocetyl thiodipropionate, diisopalmityl thiodipropionate, diisotetracosyl thiodipropionate, diisostearyl thiodipropionate, dioleyl thiodipropionate, octyl thiodipropionate, isolauryl thiodipropionate, lauryl thiodipropionate, isocetyl thiodipropionate, isostearyl thiodipropionate, oleyl thiodipropionate, octyl mercaptopropionate, stearyl mercaptopropionate, trimethylolpropane tris(mercaptopropionate), etc. Among these, from the viewpoint of compatibility in the treatment agent, ester compounds of thiodipropionic acid and an alcohol having a branched chain structure or an alcohol having an unsaturated bond are preferred.

These sulfur-containing ester compounds may be used alone or in combination of two or more.
In the treatment agent, the lower limit of the content of the sulfur-containing ester compound is preferably 0.5% by mass or more, more preferably 1% by mass or more, and may be 2% by mass or more, 3% by mass or more, 5% by mass or more, 10% by mass or more, or 15% by mass or more. The upper limit of the content of such a sulfur-containing ester compound is preferably 30% by mass or less, more preferably 25% by mass or less, and may be 20% by mass or less, 15% by mass or less, 10% by mass or less, 5% by mass or less, or 3% by mass or less. By specifying the content ratio within such a range, the effect of the present invention, particularly the scum generated on the guide, etc., for the synthetic fiber to which the treatment agent is applied can be further reduced. Note that a range in which the above upper and lower limits are arbitrarily combined is also envisioned.

The smoothing agent used in the treatment agent of this embodiment may contain other ester compounds in addition to those mentioned above. Specific examples of other ester compounds include (1) ester compounds of aliphatic monoalcohols and aliphatic monocarboxylic acids, such as octyl palmitate, oleyl laurate, oleyl oleate, isotridecyl stearate, isotetracosyl oleate, and isostearyl erucinate; (2) complete ester compounds of aliphatic monoalcohols and aliphatic polycarboxylic acids, such as diisostearyl adipate, dioleyl adipate, and dioleyl azelate; (3) ester compounds of aromatic monoalcohols and aliphatic monocarboxylic acids, such as benzyl oleate and benzyl laurate; (4) complete ester compounds of aromatic polyhydric alcohols and aliphatic monocarboxylic acids, such as bisphenol A dilaurate; and (5) complete ester compounds of aliphatic monoalcohols and aromatic polycarboxylic acids, such as bis 2-ethylhexyl phthalate, diisostearyl isophthalate, and trioctyl trimellitate.

These other ester compounds may be used alone or in combination of two or more.
As the lubricant, in addition to the above ester compounds, mineral oils (having a kinetic viscosity of 5 ^mm2 /s or more at 40°C) may be used. Examples of mineral oils include aromatic hydrocarbons, paraffinic hydrocarbons, naphthenic hydrocarbons, etc. More specifically, examples of such mineral oils include spindle oil and liquid paraffin. Commercially available products of these mineral oils can be appropriately adopted.

These mineral oils may be used alone or in combination of two or more.
In the treatment agent, the lower limit of the content of the smoothing agent is preferably 20% by mass or more, more preferably 30% by mass or more, and may be 35% by mass or more, 40% by mass or more, 45% by mass or more, 52% by mass or more, 53% by mass or more, 60% by mass or more, or 65% by mass or more. The upper limit of the content of the smoothing agent is preferably 80% by mass or less, more preferably 75% by mass or less, and may be 70% by mass or less, 65% by mass or less, 60% by mass or less, 53% by mass or less, 52% by mass or less, 45% by mass or less, 40% by mass or less, or 35% by mass or less. By specifying the range of the content ratio as such, the effect of the present invention can be further improved while imparting smoothness to the fiber. It is to be noted that a range in which the above upper and lower limits are arbitrarily combined is also envisaged.

(Nonionic surfactant)
The nonionic surfactant used in the treatment agent of this embodiment contains a compound (A) obtained by esterifying a divalent or greater and pentavalent or less polyhydric alcohol having a (poly)oxyalkylene group and a fatty acid (A1) including a monounsaturated fatty acid having two or more unsaturated bonds.

Specific examples of polyhydric alcohols having a valence of 2 to 5 include ethylene glycol, propylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2-methyl-1,2-propanediol, 1,5-pentanediol, 1,6-hexanediol, 2,5-hexanediol, 2-methyl-2,4-pentanediol, 2,3-dimethyl-2,3-butanediol, glycerin, diglycerin, triglycerin, 2-methyl-2-hydroxymethyl-1,3-propanediol, trimethylolpropane, pentaerythritol, sorbitan, and isosorbide. Among these, glycerin, sorbitan, polyethylene glycol, and isosorbide are preferred from the viewpoint of the stability of the treatment agent.

As the alkylene oxide used as a raw material for forming the (poly)oxyalkylene group, an alkylene oxide having 2 to 4 carbon atoms is preferred. Specific examples of alkylene oxide include ethylene oxide, propylene oxide, butylene oxide, etc. The number of moles of alkylene oxide added is appropriately set, but is preferably 0.1 to 250 moles, more preferably 1 to 200 moles, even more preferably 2 to 150 moles, and particularly preferably 3 to 40 moles. Any combination of the above upper and lower limits is also possible. The number of moles of alkylene oxide added indicates the number of moles of alkylene oxide per mole of the compound to be added in the raw material. As the alkylene oxide, one type of alkylene oxide may be used alone, or two or more types of alkylene oxides may be used in appropriate combination. When two or more types of alkylene oxide are used, the addition form may be any of block addition, random addition, and a combination of block addition and random addition, and is not particularly limited.

Specific examples of monounsaturated fatty acids having two or more unsaturated bonds include (1) monounsaturated fatty acids having two unsaturated bonds, such as linoleic acid, eicosadienoic acid, and docosadienoic acid; (2) monounsaturated fatty acids having three unsaturated bonds, such as α-linolenic acid, γ-linolenic acid, and eicosatrienoic acid; (3) monounsaturated fatty acids having four unsaturated bonds, such as stearidonic acid, arachidonic acid, and eicosatetraenoic acid; (4) monounsaturated fatty acids having five unsaturated bonds, such as eicosapentaenoic acid and tetracosapentaenoic acid; and (5) monounsaturated fatty acids having six unsaturated bonds, such as docosahexaenoic acid. Among these, monounsaturated fatty acids having 12 to 22 carbon atoms are preferred.

The fatty acid (A1) preferably contains at least one selected from a monounsaturated fatty acid having two unsaturated bonds and a monounsaturated fatty acid having three unsaturated bonds. By using such a monounsaturated fatty acid, the effects of the present invention can be further improved.

Compound (A) can be obtained by mixing a divalent to pentavalent polyhydric alcohol having a (poly)oxyalkylene group with a fatty acid (A1) in a predetermined mixing ratio and esterifying the mixture under conditions such as heating. Alternatively, compound (A) can be obtained by reacting an ester compound of a divalent to pentavalent polyhydric alcohol and a fatty acid (A1) with an alkylene oxide to insert a (poly)oxyalkylene group into the ester bond. The mixing ratio (molar ratio) of the divalent to pentavalent polyhydric alcohol having a (poly)oxyalkylene group and the fatty acid (A1) in the esterification reaction is appropriately set.

Specific examples of compound (A) include esters of mixed fatty acids (a mixture of linoleic acid and oleic acid) and polyethylene glycol, esters of linoleic acid and polyethylene glycol, esters of linoleic acid and an alkylene oxide adduct of glycerin, esters of linoleic acid and an alkylene oxide adduct of sorbitan, esters of linoleic acid and an alkylene oxide adduct of isosorbide, esters of linolenic acid and polyethylene glycol, esters of linolenic acid and an alkylene oxide adduct of sorbitan, etc.

These compounds (A) may be used alone or in combination of two or more.
In the treatment agent, the lower limit of the content of the compound (A) is preferably 0.1% by mass or more, more preferably 1% by mass or more, and even more preferably 2% by mass or more, and may be 3% by mass or more, 5% by mass or more, 10% by mass or more, or 12% by mass or more. When the content of the compound (A) is 0.1% by mass or more, the rubber adhesion of the synthetic fiber to which the treatment agent is applied can be further improved. The upper limit of the content of the compound (A) is preferably 20% by mass or less, more preferably 15% by mass or less, and may be 22% by mass or less, 12% by mass or less, 10% by mass or less, 5% by mass or less, or 3% by mass or less. When the content of the compound (A) is 20% by mass or less, the scum generated on the guide, etc. of the synthetic fiber to which the treatment agent is applied can be further reduced. In addition, a range in which the above upper and lower limits are arbitrarily combined is also assumed.

The nonionic surfactant used in the treatment agent of this embodiment preferably further contains a compound (B) obtained by esterifying a polyhydric alcohol having a valence of 2 to 5 and a valence of 5, which has a (poly)oxyalkylene group, with a fatty acid (B1) including a monounsaturated fatty acid having one unsaturated bond. By further containing compound (B), the nonionic surfactant can achieve both improved rubber adhesion of the synthetic fiber to which the treatment agent is applied and a reduction in scum.

Specific examples of polyhydric alcohols having a valence of 2 to 5 and having a (poly)oxyalkylene group are the same as the specific examples of polyhydric alcohols described above as the raw material for compound (A). In addition, preferred polyhydric alcohols are also the same as those for compound (A).

Specific examples of alkylene oxides used as raw materials for forming the (poly)oxyalkylene group are the same as the specific examples of alkylene oxides described above as raw materials for compound (A).

Specific examples of monounsaturated fatty acids with one unsaturated bond include crotonic acid, myristoleic acid, palmitoleic acid, oleic acid, vaccenic acid, eicosenoic acid, and erucic acid. Among these, monounsaturated fatty acids with 12 to 22 carbon atoms are preferred. Note that fatty acid (B1) does not include monounsaturated fatty acids with two or more unsaturated bonds.

Compound (B) can be obtained by mixing a divalent to pentavalent polyhydric alcohol having a (poly)oxyalkylene group with a fatty acid (B1) in a predetermined mixing ratio and esterifying the mixture under conditions such as heating. Alternatively, compound (B) can be obtained by reacting an ester compound of a divalent to pentavalent polyhydric alcohol and a fatty acid (B1) with an alkylene oxide to insert a (poly)oxyalkylene group into the ester bond. The mixing ratio (molar ratio) of the divalent to pentavalent polyhydric alcohol having a (poly)oxyalkylene group and the fatty acid (B1) in the esterification reaction is appropriately set.

Specific examples of compound (B) include esters of oleic acid and polyethylene glycol, esters of oleic acid and an alkylene oxide adduct of sorbitan, esters of palmitoleic acid and polyethylene glycol, and esters of erucic acid and polyethylene glycol.

These compounds (B) may be used alone or in combination of two or more.
In the treatment agent, the lower limit of the content of the compound (B) is preferably 3% by mass or more, more preferably 5% by mass or more, and may be 8% by mass or more, 12% by mass or more, 15% by mass or more, 16% by mass or more, or 20% by mass or more. The upper limit of the content of the compound (B) is preferably 40% by mass or less, more preferably 35% by mass or less, and may be 34% by mass or less, 20% by mass or less, 16% by mass or less, 15% by mass or less, 12% by mass or less, or 8% by mass or less. By specifying the content ratio within such a range, the effects of the present invention, particularly the improvement of rubber adhesion of the synthetic fiber to which the treatment agent is applied and the effect of reducing scum, can be achieved at the same time. Note that a range in which the above upper and lower limits are arbitrarily combined is also envisioned.

In the treatment agent, the mass ratio of the above-mentioned compound (A) to compound (B) is preferably compound (A)/compound (B) = 50/50 to 5/95, and more preferably 40/60 to 5/95. By specifying it within such a range, the effects of the present invention, in particular the improvement of rubber adhesion of the synthetic fiber to which the treatment agent is applied, and the effect of reducing scum can be achieved at the same time. In addition, the mass ratio of this compound (A) to compound (B) may be 9/91 or more, 13/87 or more, 17/83 or more, 25/75 or more, 29/71 or more, 33/67 or more, 38/62 or more, or 39/61 or more, or may be 50/50 or less, 39/61 or less, 38/62 or less, 33/67 or less, 29/71 or less, 25/75 or less, 17/83 or less, or 13/87 or less.

In the treatment agent, the total content of the above-mentioned compound (A) and compound (B) is preferably 10% by mass or more and 40% by mass or less. By specifying this range, the effects of the present invention, in particular the improvement of rubber adhesion of the synthetic fiber to which the treatment agent is applied and the effect of reducing scum, can be achieved at the same time.

The nonionic surfactant used in the treatment agent of this embodiment may further contain a compound (C) obtained by esterifying a polyhydric alcohol having a valence of 2 to 5 and a valence of 5, and having a (poly)oxyalkylene group, with a fatty acid (C1) including a monovalent saturated fatty acid.

Specific examples of monosaturated fatty acids include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, hexanoic acid (caproic acid), octylic acid (2-ethylhexanoic acid), octanoic acid (caprylic acid), nonanoic acid, decanoic acid (capric acid), dodecanoic acid (lauric acid), tetradecanoic acid (myristic acid), hexadecanoic acid (palmitic acid), octadecanoic acid (stearic acid), eicosanoic acid (arachidic acid), docosanoic acid (behenic acid), and tetracosanoic acid. Among these, monosaturated fatty acids with 12 to 22 carbon atoms are preferred. Note that fatty acids (C1) do not include monounsaturated fatty acids.

Compound (C) can be obtained by mixing a divalent to pentavalent polyhydric alcohol having a (poly)oxyalkylene group with a fatty acid (C1) in a predetermined mixing ratio and esterifying the mixture under conditions such as heating. Alternatively, compound (C) can be obtained by reacting an ester compound of a divalent to pentavalent polyhydric alcohol and a fatty acid (C1) with an alkylene oxide to insert a (poly)oxyalkylene group into the ester bond. The mixing ratio (molar ratio) of the divalent to pentavalent polyhydric alcohol having a (poly)oxyalkylene group and the fatty acid (C1) in the esterification reaction is appropriately set.

Specific examples of compound (C) include esters of mixed fatty acids (a mixture of palmitic acid and stearic acid) and polyethylene glycol, and esters of mixed fatty acids (a mixture of lauric acid, myristic acid, and palmitic acid) and polyethylene glycol.

These compounds (C) may be used alone or in combination of two or more.
In the treatment agent, the lower limit of the content of the compound (C) is preferably 0.1% by mass or more, more preferably 1% by mass or more, and may be 2% by mass or more or 5% by mass or more. The upper limit of the content of the compound (C) is preferably 20% by mass or less, more preferably 15% by mass or less, and may be 14% by mass or less or 5% by mass or less. By defining the content of the compound (C) in this range, the effect of the present invention can be further improved. In addition, a range in which the above upper and lower limits are arbitrarily combined is also envisioned.

In addition, when the total content of the compounds (A), (B), and (C) in the treatment agent is taken as 100% by mass, the total content of the compounds (A) and (B) is preferably 50% by mass or more, more preferably 70% by mass or more. By being specified within such a range, it is possible to achieve both an improvement in rubber adhesion of the synthetic fiber to which the treatment agent is applied and an effect of reducing scum. When the total content of the compounds (A), (B), and (C) is taken as 100% by mass, the total content of the compounds (A) and (B) may be 65% by mass or more, 81% by mass or more, 82% by mass or more, 86% by mass or more, or 90% by mass or more.

The treatment agent of this embodiment may further contain a nonionic surfactant other than the above-mentioned compounds (A) to (C).
Other nonionic surfactants include, for example, compounds having a (poly)oxyalkylene structure in which alkylene oxides are added to alcohols or carboxylic acids, ether/ester compounds having a (poly)oxyalkylene structure in which alkylene oxides are added to ester compounds of carboxylic acids and polyhydric alcohols, amine compounds such as compounds having a (poly)oxyalkylene structure in which alkylene oxides are added to primary organic amines, partial ester compounds of carboxylic acids and polyhydric alcohols, amide compounds in which amine compounds are condensed with carboxylic acids, and compounds having a (poly)oxyalkylene structure in which alkylene oxides are added to fatty acid amides.

Specific examples of alcohols used as raw materials for nonionic surfactants include, for example, (1) straight-chain alkyl alcohols such as methanol, ethanol, propanol, butanol, pentanol, hexanol, octanol, nonanol, decanol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, hexadecanol, heptadecanol, octadecanol, nonadecanol, eicosanol, heneicosanol, docosanol, tricosanol, tetracosanol, pentacosanol, hexacosanol, heptacosanol, octacosanol, nonacosanol, and triacontanol; (2) isopropanol, isobutanol, isohexanol, 2-ethylhexanol, isononanol, isodecanol, isododecanol, isotridecanol, isotetradecanol, isopentadecanol, and isohexa. Branched alkyl alcohols such as decanol, isoheptadecanol, isooctadecanol, isonadecanol, isoeicosanol, isoheneicosanol, isodocosanol, isotricosanol, isotetracosanol, isopentacosanol, isohexacosanol, isoheptacosanol, isooctacosanol, isononacosanol, and isotriacontanol; (3) linear alkenyl alcohols such as tetradecenol, hexadecenol, heptadecenol, octadecenol, and nonadecenol; (4) branched alkenyl alcohols such as isohexadecenol and isooctadecenol; (5) cyclic alkyl alcohols such as cyclopentanol and cyclohexanol; and (6) aromatic alcohols such as phenol, nonylphenol, benzyl alcohol, monostyrenated phenol, distyrenated phenol, and tristyrenated phenol.

Specific examples of carboxylic acids used as raw materials for nonionic surfactants include (1) linear alkyl carboxylic acids such as octylic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid, nonadecanoic acid, eicosanoic acid, heneicosanoic acid, and docosanoic acid; (2) branched alkyl carboxylic acids such as 2-ethylhexanoic acid, isododecanoic acid, isotridecanoic acid, isotetradecanoic acid, isohexadecanoic acid, and isooctadecanoic acid; (3) linear alkenyl carboxylic acids such as octadecenoic acid, octadecadienoic acid, and octadecatrienoic acid; (4) aromatic carboxylic acids such as benzoic acid; (5) hydroxycarboxylic acids such as lactic acid, citric acid, and ricinoleic acid; and (6) polyvalent carboxylic acids such as adipic acid, sebacic acid, and tricarbaryl.

Specific examples of alkylene oxides used as raw materials to form the (poly)oxyalkylene structure of the nonionic surfactant are the same as the specific examples of alkylene oxides described above as raw materials for compound (A).

Specific examples of polyhydric alcohols used as raw materials for nonionic surfactants include sucrose, sorbitol, polyglycerin, etc., in addition to the polyhydric alcohols described above as raw materials for compound (A).

Specific examples of amine compounds used as raw materials for nonionic surfactants include methylamine, ethylamine, butylamine, octylamine, laurylamine, octadecylamine (stearylamine), octadecenylamine, coconut amine, and ethyleneamine.

Specific examples of fatty acid amides used as raw materials for nonionic surfactants include octyl acid amide, lauric acid amide, palmitic acid amide, stearic acid amide, oleic acid amide, behenic acid amide, lignoceric acid amide, amides of fatty acids and diethanolamine, and amides of fatty acids and ethyleneamine.

Specific examples of nonionic surfactants include alkylene oxide adducts of monohydric alcohols, alkylene oxide adducts of castor oil and its derivatives, esters of alkylene oxide adducts of castor oil and its derivatives and fatty acids, partial esters of polyhydric alcohols having 3 to 6 carbon atoms and carboxylic acids, alkylene oxide adducts of fatty acid amides, and alkylene oxides of primary alkylamines. Specific examples of the alkylene oxide include isododecanol to which an alkylene oxide has been added, oleyl alcohol to which an alkylene oxide has been added, isotetradecanol to which an alkylene oxide has been added, hydrogenated castor oil to which an alkylene oxide has been added, a compound obtained by esterifying hydrogenated castor oil to which an alkylene oxide has been added with oleic acid, a compound obtained by crosslinking hydrogenated castor oil to which an alkylene oxide has been added with adipic acid and then esterifying it with stearic acid, glycerin dioleate, a diester of trimethylolpropane and isostearic acid, a compound obtained by esterifying sorbitol to a mixed fatty acid (palmitic acid, oleic acid, and linoleic acid), an alkylene oxide adduct of oleyl diethanolamide, an alkylene oxide adduct of laurylamine, and an alkylene oxide adduct of stearylamine.

These other nonionic surfactants may be used alone or in appropriate combination of two or more kinds.
In the treatment agent, the lower limit of the content ratio of the total nonionic surfactant is preferably 20% by mass or more, more preferably 25% by mass or more, and may be 33% by mass or more, 35% by mass or more, 37% by mass or more, 43% by mass or more, 44% by mass or more, 45% by mass or more, 46% by mass or more, 53% by mass or more, 56% by mass or more, 62% by mass or more, or 66% by mass or more. The upper limit of the content ratio of such nonionic surfactant is preferably 75% by mass or less, more preferably 70% by mass or less, and may be 67% by mass or less, 66% by mass or less, 62% by mass or less, 56% by mass or less, 53% by mass or less, 46% by mass or less, 45% by mass or less, 44% by mass or less, 43% by mass or less, 37% by mass or less, 35% by mass or less, or 33% by mass or less. By specifying the range of the content ratio, the effect of the present invention can be further improved. In addition, a range in which the above upper and lower limits are arbitrarily combined is also envisioned.

(Ionic Surfactant)
The treatment agent of the present embodiment may further contain an ionic surfactant. Examples of the ionic surfactant include anionic surfactants, cationic surfactants, and amphoteric surfactants.

As the anionic surfactant, known surfactants can be appropriately used. Specific examples of anionic surfactants include (1) phosphate salts of aliphatic alcohols, such as lauryl phosphate salts, cetyl phosphate salts, isocetyl phosphate salts, octyl phosphate salts, oleyl phosphate salts, and stearyl phosphate salts; and (2) aliphatic alcohols, such as polyoxyethylene lauryl ether phosphate salts, polyoxyethylene oleyl ether phosphate salts, and polyoxyethylene stearyl ether phosphate salts, which are combined with at least one of ethylene oxide and propylene oxide. (3) aliphatic or aromatic sulfonates such as lauryl sulfonate, myristyl sulfonate, cetyl sulfonate, oleyl sulfonate, stearyl sulfonate, tetradecane sulfonate, dodecylbenzene sulfonate, secondary alkane sulfonate (having 13 to 15 carbon atoms), secondary alkane sulfonate (having 11 to 14 carbon atoms), and α-olefin sulfonate; (4) sulfates of aliphatic alcohols such as lauryl sulfate, oleyl sulfate, and stearyl sulfate. (5) sulfates of fatty alcohols to which at least one alkylene oxide selected from ethylene oxide and propylene oxide has been added, such as polyoxyethylene lauryl ether sulfate, polyoxyalkylene (polyoxyethylene, polyoxypropylene) lauryl ether sulfate, and polyoxyethylene oleyl ether sulfate; (6) castor oil fatty acid sulfate, sesame oil fatty acid sulfate, tall oil fatty acid sulfate, soybean oil fatty acid sulfate, and rapeseed oil fatty acid sulfate. (6) sulfate salts of fats and oils, such as sulfate salts of castor oil, sulfate salts of sesame oil, sulfate salts of tall oil, sulfate salts of soybean oil, sulfate salts of rapeseed oil, and sulfate salts of palm oil; (7) sulfate salts of fats and oils, such as sulfate salts of castor oil, sulfate salts of sesame oil, sulfate salts of tall oil, sulfate salts of soybean oil, sulfate salts of rapeseed oil, and sulfate salts of palm oil; (8) fatty acid salts, such as laurates, oleates, stearates, and 2-ethylhexanoates; (9) sulfosuccinate salts of fatty alcohols, such as di(2-ethylhexyl)sulfosuccinate; and (10) N-acyl sarcosine salts, such as oleoyl sarcosine salt.

Examples of salts constituting the anionic surfactant include metal salts, ammonium salts, phosphonium salts, and organic amine salts.
Examples of the metal salt include alkali metal salts and alkaline earth metal salts. Specific examples of the alkali metal constituting the alkali metal salt include sodium, potassium, lithium, etc. Examples of the alkaline earth metal constituting the alkaline earth metal salt include metals belonging to Group 2 elements, such as calcium, magnesium, beryllium, strontium, barium, etc.

Specific examples of phosphoniums constituting phosphonium salts include quaternary phosphoniums such as tetramethylphosphonium, tetraethylphosphonium, tetrabutylphosphonium, tetraoctylphosphonium, dibutyldihexylphosphonium, trihexyltetradecylphosphonium, triethyloctylphosphonium, trioctylmethylphosphonium, and triphenylmethylphosphonium.

The amine constituting the organic amine salt may be a primary amine, a secondary amine, or a tertiary amine. Specific examples of amines constituting the amine salt include, for example, (1) aliphatic amines such as methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, N-N-diisopropylethylamine, butylamine, dibutylamine, 2-methylbutylamine, tributylamine, octylamine, and dimethyllaurylamine; (2) aromatic amines or heterocyclic amines such as aniline, N-methylbenzylamine, pyridine, morpholine, piperazine, and derivatives thereof; (3) alkanolamines such as monoethanolamine, N-methylethanolamine, diethanolamine, triethanolamine, isopropanolamine, diisopropanolamine, triisopropanolamine, dibutylethanolamine, butyldiethanolamine, octyldiethanolamine, and lauryldiethanolamine; (4) arylamines such as N-methylbenzylamine; and (5) polyoxyalkylene alkylamino ethers such as polyoxyethylene lauryl amino ether and polyoxyethylene steryl amino ether.

　Any known cationic surfactant can be used as appropriate. Specific examples of cationic surfactants include lauryl trimethyl ammonium chloride, cetyl trimethyl ammonium chloride, stearyl trimethyl ammonium chloride, behenyl trimethyl ammonium chloride, didecyl dimethyl ammonium chloride, and 1,2-dimethyl imidazole.

As the amphoteric surfactant, known surfactants can be appropriately used. Specific examples of the amphoteric surfactant include betaine-type amphoteric surfactants.
These ionic surfactants may be used alone as one type of ionic surfactant, or as a suitable combination of two or more types of ionic surfactants.

The lower limit of the content of the ionic surfactant in the treatment agent is preferably 1% by mass or more, more preferably 2% by mass or more, and may be 3% by mass or more or 4% by mass or more. The upper limit of the content of the ionic surfactant is preferably 10% by mass or less, more preferably 5% by mass or less, and may be 4% by mass or less or 3% by mass or less. By specifying the content within such a range, the effect of the present invention can be further improved. Note that ranges that combine the above upper and lower limits in any way are also envisioned.

Second Embodiment
Next, a second embodiment of the synthetic fiber according to the present invention will be described. The synthetic fiber of this embodiment has the treatment agent of the first embodiment attached thereto. According to this embodiment, a treated synthetic fiber is provided that includes a synthetic fiber and a treatment agent attached thereto. The form of the treatment agent when attached to the synthetic fiber may be a dilution liquid diluted with a dilution solvent, such as an organic solvent solution or an aqueous liquid. From the viewpoint of the adhesion of the treatment agent to the fiber and economic efficiency, it is preferable to use a hydrocarbon having a carbon number of 10 to 15 and/or water as the dilution solvent. The mixing ratio of the treatment agent and the dilution solvent is preferably 99:1 to 10:90 (mass of treatment agent:mass of dilution solvent). The dilution liquid such as an aqueous liquid is attached to the synthetic fiber in, for example, a spinning or drawing process. The dilution solvent attached to the synthetic fiber may be evaporated by a drawing process or a drying process. The effect of the invention can be further expected by using the synthetic fiber in a manufacturing facility or process that has a process of passing the synthetic fiber through a roller at 150°C or higher in the drawing or heat treatment process.

Specific examples of synthetic fibers to which the treatment agent of this embodiment is applied are not particularly limited, and include, for example, (1) polyester fibers such as polyethylene terephthalate (PET), polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polylactic acid, and composite fibers containing these polyester resins, (2) polyamide fibers such as nylon 6 and nylon 66, (3) polyacrylic fibers such as polyacrylic and modacrylic, and (4) polyolefin fibers such as polyethylene and polypropylene. Among these, it is preferable to apply the treatment agent to polyester fibers and polyamide fibers. There is no particular limit to the fineness of the synthetic fibers to be manufactured, but it is preferably 150 decitex or more, more preferably 500 decitex or more, and even more preferably 1000 decitex or more. In addition, there is no particular limit to the strength of the synthetic fibers to be manufactured, but it is preferably 5.0 cN/dtex or more, more preferably 6.0 cN/dtex or more, and even more preferably 7.0 cN/dtex or more.

There is no particular limit to the ratio of the treatment agent applied to the synthetic fibers, but it is preferable to apply the treatment agent at a ratio of 0.1% to 5% by mass (not including solvents such as water) relative to the synthetic fibers. This configuration further improves the effects of the present invention. There is also no particular limit to the method of applying the treatment agent, and known methods such as roller oiling, guide oiling using a metering pump, immersion oiling, and spray oiling can be used.

In the present invention, the use of the synthetic fibers is not particularly limited, but synthetic fibers used in industrial materials are preferred. For example, synthetic fibers used in the fields of automobiles, architecture, commerce, agriculture/fisheries, civil engineering, etc., such as fibers for airbags, seat belts, tire cords, carpets, tents, advertising fabrics, fishing nets, conveyor belts, and ropes, are more preferred.

The effects of the treatment agent and synthetic fibers of the above embodiment will be described.
(1) The treatment agent of the above embodiment is composed of a blend of the above-mentioned smoothing agent and the above-mentioned nonionic surfactant. Therefore, it is possible to improve the rubber adhesion of the synthetic fiber to which the treatment agent for synthetic fibers is applied and to reduce scum. In particular, even if the synthetic fiber to which the treatment agent is applied is stored for a long period of time, it is possible to reduce scum on guides, etc.

Industrial fiber is often used for rubber adhesion, that is, by bonding it to rubber. The rubber adhesion of fiber to which a treatment agent has been applied tends to increase with an increase in the number of unsaturated bonds in the treatment agent. However, an increase in unsaturated bonds can also cause tar generation in processes where heat is applied. Furthermore, if the treatment agent changes on the synthetic fiber during storage after spinning, it can affect post-processing, such as causing scum adhesion to the guide, fluctuations in unwinding tension, and stickiness and stickiness of the fiber. The configuration of the present invention described above makes it possible to achieve both spinning and post-processing performance.

The above embodiment may be modified as follows: The above embodiment and the following modifications may be combined with each other to the extent that no technical contradiction occurs.
The treatment agent of the above embodiment may further contain components that are typically used in treatment agents, such as stabilizers, antistatic agents, binders, UV absorbers, defoamers, preservatives, and rust inhibitors, other than those mentioned above, during or after production of the treatment agent, to maintain the quality of the treatment agent, within the scope of not impairing the effects of the present invention.

- To improve the stability of the appearance of the treatment agent during storage, the treatment agent may be mixed with water in advance. In this case, the mixing ratio of the treatment agent to the water (mass of treatment agent:mass of water) is preferably 85:15 to 99.9:0.1.

Below, examples are given to more specifically explain the configuration and effects of the present invention, but the present invention is not limited to these examples. In the following explanations of the examples and comparative examples, parts means parts by mass, and % means % by mass, unless otherwise specified.

Test section 1 (preparation of treatment agent)
Example 1
As shown in Table 1, the lubricating agent was 10 parts (%) of diisocetyl thiodipropionate (ES-1), 30 parts (%) of triester of trimethylolpropane and mixed acid (palm kernel fatty acid and vegetable oleic acid, mass ratio 4:6 mixture) (E-1), 20 parts (%) of rapeseed oil (E-2), 5 parts (%) of compound (A-1) shown in Table 3 below as a nonionic surfactant, 8 parts (%) of compound (B-1) shown in Table 4 below as a nonionic surfactant, 10 moles of ethylene oxide (hereinafter referred to as "EO") and 10 moles of propylene oxide (hereinafter referred to as "PO") randomly added to 1 mole of isododecanol (N-3), The treatment agent of Example 1 contained 5 parts (%) of a compound (mass average molecular weight 7000) (N-7), 10 parts (%) of a compound obtained by adding 10 moles of EO to 1 mole of hydrogenated castor oil (N-5), 5 parts (%) of a compound obtained by adding 15 moles of EO to 1 mole of hydrogenated castor oil and crosslinking it with adipic acid and esterifying it with stearic acid (mass average molecular weight 7000) (N-7), 2 parts (%) of a compound obtained by adding 5 moles of EO to 1 mole of laurylamine (N-12), 3 parts (%) of a secondary alkane sulfonic acid sodium salt (having 11 to 14 carbon atoms) (D-1) as an ionic surfactant, and 2 parts (%) of a phosphoric ester-dibutylethanolamine salt of an oleyl alcohol adduct with 5 moles of EO (D-5).

(Examples 2 to 14, Comparative Examples 1 to 4)
The treatment agents of Examples 2 to 14 and Comparative Examples 1 to 4 were prepared in the same manner as the treatment agent of Example 1 so as to contain the leveling agent, nonionic surfactant, and ionic surfactant in the proportions shown in Table 1.

The type and content of the smoothing agent, the type and content of the nonionic surfactant, and the type and content of the ionic surfactant are shown in the "Smoothing agent" column, the "Nonionic surfactant" column, and the "Ionic surfactant" column in Table 1, respectively. The mass ratio of the nonionic surfactant compounds (A) and (B) is shown in the "Mass ratio (A)/(B)" column. When the total content of the nonionic surfactant compounds (A), (B), and (C) is taken as 100%, the total content of compounds (A) and (B) is shown in the "Mass ratio [(A)+(B)]/[(A)+(B)+(C)]" column.

Details of the smoothing agent, nonionic surfactant, and ionic surfactant listed in Table 1 are as follows.
<Smoothing Agent>
(Sulfur-containing ester compounds)
ES-1: Diisocetyl thiodipropionate ES-2: Dioleyl thiodipropionate ES-3: Diisostearyl thiodipropionate (complete ester compound of polyhydric alcohol and monovalent fatty acid)
E-1: Triester of trimethylolpropane and mixed acid (a mixture of palm kernel fatty acid and vegetable oleic acid, a mass ratio of 4:6) E-2: Rapeseed oil E-3: Triester of glycerin and mixed acid (a mixture of palm kernel fatty acid and vegetable oleic acid, a mass ratio of 4:6) (Other smoothing agents)
E-4: Di(isostearyl)adipate E-5: Oleyl palmitate <Nonionic surfactant>
(Compound (A))
Compounds (A-1) to (A-7) shown in Table 3 below were used as compounds (A) obtained by esterifying a polyhydric alcohol having a valence of 2 to 5 and a monounsaturated fatty acid having two or more unsaturated bonds with a polyhydric alcohol having a (poly)oxyalkylene group. Compounds (rA-1) and (rA-2) shown in Table 3 were used as compounds similar to compound (A). The types of fatty acid (A1) and polyhydric alcohol used as raw materials for compound (A), as well as the charge ratio (molar ratio) of fatty acid (A1) and polyhydric alcohol, are shown in the "monounsaturated fatty acid (A1)" column, the "polyhydric alcohol" column, and the "reaction ratio" column in Table 3. As a result of qualitative analysis of compound (A-1) by liquid chromatography, no compound corresponding to compound (B) was contained. In the "polyhydric alcohol" column, PEG400 indicates polyethylene glycol having a mass average molecular weight of 400, and PEG600 indicates polyethylene glycol having a mass average molecular weight of 600.

(Compound (B))
Compounds (B-1) to (B-7) shown in Table 4 below were used as compounds (B) obtained by esterifying a polyhydric alcohol having a valence of 2 to 5 and a valence of 5, each having a (poly)oxyalkylene group, and a fatty acid (B1) including a monounsaturated fatty acid having one unsaturated bond. The types of fatty acid (B1) and polyhydric alcohol used as raw materials for compound (B) and the charge ratio (molar ratio) of fatty acid (B1) and polyhydric alcohol are shown in the "Monounsaturated fatty acid (B1)" column, the "Polyhydric alcohol" column, and the "Reaction ratio" column in Table 4. In the "Polyhydric alcohol" column, PEG400 indicates polyethylene glycol having a mass average molecular weight of 400, PEG600 indicates polyethylene glycol having a mass average molecular weight of 600, and PEG1000 indicates polyethylene glycol having a mass average molecular weight of 1000.

(Compound (C))
Compounds (C-1) and (C-2) shown in Table 5 below were used as compounds (C) obtained by esterifying a divalent to pentavalent polyhydric alcohol having a (poly)oxyalkylene group and a fatty acid (C1) including a monovalent saturated fatty acid. The types of fatty acid (C1) and polyhydric alcohol used as raw materials for compound (C) and the charge ratio (molar ratio) of fatty acid (C1) to polyhydric alcohol are shown in the "Monovalent saturated fatty acid (C1)" column, the "Polyhydric alcohol" column, and the "Reaction ratio" column of Table 5, respectively. In the "Polyhydric alcohol" column, PEG400 indicates polyethylene glycol having a mass average molecular weight of 400, and PEG600 indicates polyethylene glycol having a mass average molecular weight of 600.

(Other nonionic surfactants)
N-1: 10 moles of EO added to 1 mole of isododecanol. N-2: 10 moles of EO added to 1 mole of oleyl alcohol. N-3: 10 moles of EO and 10 moles of PO added randomly to 1 mole of isododecanol. N-4: 15 moles of PO added to 1 mole of isotetradecanol and 15 moles of EO added to the resulting mixture. N-5: 10 moles of EO added to 1 mole of hydrogenated castor oil. N-6: A compound obtained by esterifying 15 moles of EO added to 1 mole of hydrogenated castor oil with 3 moles of oleic acid. N-7: A compound obtained by crosslinking 15 moles of EO added to 1 mole of hydrogenated castor oil with adipic acid and esterifying with stearic acid (mass average molecular weight 7000).
N-8: Glycerin dioleate N-9: Diester of trimethylolpropane and isostearic acid N-10: Compound obtained by esterifying sorbitol and mixed fatty acid (palmitic acid, oleic acid, and linoleic acid in a mass ratio of 7/75/18) (reaction molar ratio 1:1)
N-11: 8 moles of EO added to 1 mole of oleyldiethanolamide. N-12: 5 moles of EO added to 1 mole of laurylamine. N-13: 10 moles of EO added to 1 mole of stearylamine. <Ionic surfactants>
D-1: Sodium secondary alkane sulfonate (carbon number 11 to 14)
D-2: Di(2-ethylhexyl)sulfosuccinic acid sodium salt D-3: α-olefin sulfonic acid sodium salt D-4: 2-ethylhexanoic acid potassium salt D-5: phosphate ester-dibutylethanolamine salt of oleyl alcohol EO 5 mol adduct D-6: isocetyl phosphate ester-stearylamine EO 10 mol adduct salt The mass average molecular weight was measured by gel permeation chromatography using polystyrene as a standard substance.

Test category 2 (adhesion)
Each of the treatment agents prepared as above was uniformly diluted with an organic solvent (a mixed solvent of hexane and ethanol) as a dilution solvent to obtain a 15% dilution solution. The dilution solution was applied to oil-free polyethylene terephthalate fibers having 1670 decitex, 288 filaments, and an intrinsic viscosity of 0.93 in the spinning process by an oiling roller oiling method so that the amount applied was 5.0% as non-volatile content. The dilution solvent was then dried to obtain a test yarn.

Two test yarns were twisted with 40 twists per 10 cm for the first twist and 40 twists per 10 cm for the second twist to form a twisted cord. This twisted cord was immersed in a first adhesive (epoxy compound (Denacol EX-512, product of Nagase ChemteX Corporation)/blocked isocyanate (Elastron BN-27, product of Daiichi Kogyo Seiyaku Co., Ltd.) = 5/5 (solids ratio)) and then heat-treated. Next, it was further immersed in a second adhesive (RFL solution of resorcin (Resorcinol, product of Kishida Chemical Co., Ltd.)/formalin (Formaldehyde Liquid (37%), product of Kishida Chemical Co., Ltd.)/latex (Nipol 2518FS, product of Nippon Zeon Co., Ltd.) = 1.5/0.5/8 (solids ratio)) and then heat-treated to obtain a reinforcing cord treated with an adhesive. The reinforcing cord was placed closely on top of unvulcanized rubber measuring 2.5 cm in length and 12.5 cm in width, and unvulcanized rubber was placed on top of the reinforcing cord. This was then press-vulcanized at 150°C and 4 MPa for 30 minutes to create a test specimen for evaluating rubber adhesion. After cooling, the reinforcing cord was peeled off from the rubber at a peeling speed of 50 mm/min, and the adhesion of the rubber to the reinforcing cord was visually observed and evaluated according to the following criteria. The results are shown in the "Adhesion" column in Table 2.

Adhesion evaluation criteria ○○ (good): When the rubber is attached to such an extent that the reinforcing cord is not visible ○ (passable): When the rubber is attached to such an extent that the reinforcing cord is barely visible × (unacceptable): When the reinforcing cord is clearly visible Test category 3 (scum)
The test yarn obtained in test section 2 was stored at 60°C for 6 weeks, and then contacted with a ceramic guide for 5 minutes at an initial tension of 0.5 kg and a yarn speed of 50 m/min. The amount of scum adhering to the ceramic guide was visually observed and evaluated according to the following criteria. The results are shown in the "Scum" column in Table 2.

Scum evaluation criteria XX (good): no scum observed ○ (pass): faint scum observed × (unpassable): clearly scum observed As is clear from the results in Table 2, the treatments in each example were rated pass or better in both adhesion and scum. According to the present invention, it is possible to achieve both improved rubber adhesion and reduced scum on synthetic fibers to which the treatment for synthetic fibers has been applied.

The present disclosure also encompasses the following aspects.
(Appendix 1)
A synthetic fiber treatment agent containing a smoothing agent and a nonionic surfactant,
the smoothing agent contains a complete ester compound of a polyhydric alcohol having a chain structure containing 3 to 6 carbon atoms and a monovalent fatty acid having 8 to 24 carbon atoms,
the nonionic surfactant comprises a compound (A) obtained by esterifying a divalent to pentavalent polyhydric alcohol having a (poly)oxyalkylene group and a fatty acid (A1) containing at least one selected from a monounsaturated fatty acid having 12 to 22 carbon atoms and having two unsaturated bonds, and a monounsaturated fatty acid having 12 to 22 carbon atoms and having three unsaturated bonds, and a compound (B) obtained by esterifying a divalent to pentavalent polyhydric alcohol having a (poly)oxyalkylene group and a fatty acid (B1) containing a monounsaturated fatty acid having one unsaturated bond,
The synthetic fiber treating agent contains the completely esterified compound in an amount of 30% by mass or more and 70% by mass or less, and the compound (A) in an amount of 0.1% by mass or more and 22% by mass or less.

(Appendix 2)
A synthetic fiber treatment agent containing a smoothing agent and a nonionic surfactant,
the smoothing agent comprises a complete ester compound of a polyhydric alcohol having a chain structure containing 3 to 6 carbon atoms and a monovalent fatty acid having 8 to 24 carbon atoms, and a sulfur-containing ester compound;
the nonionic surfactant comprises a compound (A) obtained by esterifying a divalent to pentavalent polyhydric alcohol having a (poly)oxyalkylene group and a fatty acid (A1) containing at least one selected from a monounsaturated fatty acid having 12 to 22 carbon atoms and two unsaturated bonds, and a monounsaturated fatty acid having 12 to 22 carbon atoms and three unsaturated bonds;
The synthetic fiber treating agent contains the completely esterified compound in an amount of 30% by mass or more and 70% by mass or less, and the compound (A) in an amount of 0.1% by mass or more and 22% by mass or less.

(Appendix 3)
The treatment agent for synthetic fibers according to Appendix 1, wherein the mass ratio of the compound (A) to the compound (B) in the treatment agent for synthetic fibers is compound (A)/compound (B)=40/60 to 5/95.

(Appendix 4)
the nonionic surfactant further comprises a compound (C) obtained by esterifying a dihydric to pentahydric polyhydric alcohol having a (poly)oxyalkylene group with a fatty acid (C1) including a monohydric saturated fatty acid,
The treatment agent for synthetic fibers according to Appendix 1, containing the compound (A) and the compound (B) in a total amount of 70 mass% or more when the total content of the compound (A), the compound (B), and the compound (C) is 100 mass%.

(Appendix 5)
2. The synthetic fiber treating agent according to claim 1, wherein the smoothing agent further comprises a sulfur-containing ester compound.
(Appendix 6)
The synthetic fiber treating agent according to claim 1, further comprising an ionic surfactant.

(Appendix 7)
A synthetic fiber having a synthetic fiber treating agent according to any one of claims 1 to 6 adhered thereto.

Claims

Contains a smoothing agent and a nonionic surfactant,
The smoothing agent comprises a complete ester compound of a polyhydric alcohol and a monohydric fatty acid,
The synthetic fiber treatment agent is characterized in that the nonionic surfactant contains a compound (A) obtained by esterifying a polyhydric alcohol having a valence of 2 to 5 and a valence of 1 to 5 and having a (poly)oxyalkylene group with a fatty acid (A1) including a monounsaturated fatty acid having two or more unsaturated bonds.
The synthetic fiber treatment agent according to claim 1, wherein the fatty acid (A1) contains at least one selected from a monounsaturated fatty acid having two unsaturated bonds and a monounsaturated fatty acid having three unsaturated bonds.
The synthetic fiber treatment agent according to claim 1, wherein the compound (A) is contained in the synthetic fiber treatment agent in a proportion of 0.1% by mass or more and 20% by mass or less.
The synthetic fiber treatment agent according to claim 1, wherein the nonionic surfactant further contains a compound (B) obtained by esterifying a polyhydric alcohol having a valence of 2 to 5 and a valence of 5, and a fatty acid (B1) including a monounsaturated fatty acid having one unsaturated bond.
The synthetic fiber treatment agent according to claim 4, wherein the mass ratio of the compound (A) and the compound (B) in the synthetic fiber treatment agent is compound (A)/compound (B) = 40/60 to 5/95.
the nonionic surfactant further comprises a compound (C) obtained by esterifying a dihydric to pentahydric polyhydric alcohol having a (poly)oxyalkylene group with a fatty acid (C1) including a monohydric saturated fatty acid,
5. The treatment agent for synthetic fibers according to claim 4, wherein the compound (A) and the compound (B) are contained in a total amount of 70 mass% or more when the total content of the compound (A), the compound (B), and the compound (C) is 100 mass%.
The synthetic fiber treatment agent according to claim 1, wherein the smoothing agent further contains a sulfur-containing ester compound.
The synthetic fiber treatment agent according to claim 1 further contains an ionic surfactant.
Synthetic fibers having the synthetic fiber treatment agent according to any one of claims 1 to 8 attached thereto.