Treatment agent for synthetic fiber and synthetic fiber

Abstract

The present invention aims to improve the permeability of an adhesive between synthetic fibers and the high-temperature burr-inhibiting effect. A treatment agent for synthetic fibers contains a smoothing agent (A) containing a fully esterified compound (A1) described below and a dicarboxylic acid compound (B) described below. The fully esterified compound (A1) is a fully esterified compound of a polyhydric alcohol of three or more and four or less with a monovalent carboxylic acid. The dicarboxylic acid compound (B) is at least one selected from a dicarboxylic acid having 3 or more and 10 or less carbon atoms and a salt thereof having 0 or more and 1 or less hydroxyl groups in the molecule.

Description

Technical Field

[0001] This invention relates to a synthetic fiber treatment agent and synthetic fibers that can improve the penetration of adhesives between fibers and the high-temperature burr suppression effect of synthetic fibers. Background Technology

[0002] In the spinning and stretching processes of synthetic fibers, treatments are sometimes performed to adhere a treatment agent to the surface of the synthetic fibers in order to improve aspects such as smoothness and antistatic properties.

[0003] In addition, synthetic fibers are widely used as industrial materials. For example, they are used in the automotive industry for tire cords and airbags; in the construction industry for carpets and tents; in the commercial industry for advertising fabrics; in the agricultural / aquaculture industry for ropes and fishing nets; and in the civil engineering industry for conveyor belts and lifelines. Among these, they are widely used as reinforcing materials for rubber products. When used as a reinforcing material for rubber products, an adhesive is applied to the synthetic fibers and then bonded to the rubber material.

[0004] For example, during yarn manufacturing, a treatment agent is applied to synthetic fibers, and the twisted yarns of the synthetic fibers are woven to create a fabric. An adhesive is then applied to the fabric to bond it to a rubber material. Alternatively, the treatment agent and adhesive are pre-mixed to create a mixture. During yarn manufacturing, the mixture is applied to synthetic fibers, and the twisted yarns of the synthetic fibers are woven to create a fabric. The fabric is then bonded to a rubber material. Alternatively, during yarn manufacturing, the treatment agent and adhesive are separately applied to synthetic fibers, and the twisted yarns of the synthetic fibers are woven to create a fabric. The fabric is then bonded to a rubber material. Alternatively, the bonding to the rubber material is performed not only on the fabric but also on the raw yarn and the twisted yarn.

[0005] Previously known treatment agents for synthetic fibers were disclosed in Patent Documents 1 to 3. Patent Document 1 discloses a spinning oil containing polyether for false twisting. Patent Document 2 discloses a friction false twisting oil for synthetic fibers containing polyether, carboxylates, alkyl phosphates, and aliphatic diacids. Patent Document 3 discloses a treatment agent for polyamide fibers containing ester components, amides, and polyoxyethylene-modified silicone.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Publication No. 5-65625

[0009] Patent Document 2: Japanese Patent No. 4463327

[0010] Patent Document 3: Japanese Patent No. 3165284 Summary of the Invention

[0011] The problem that the invention aims to solve

[0012] However, none of the existing synthetic fiber treatment agents mentioned above consider the adhesion of the adhesive to the synthetic fibers when they are used as reinforcing materials in rubber products. To improve the adhesion of the adhesive to the synthetic fibers, one approach is to improve the penetration of the adhesive between the fibers. Improved adhesion allows the adhesive to be evenly coated onto the fibers, suppressing uneven bonding. Furthermore, it can suppress losses due to adhesive scattering during the adhesion process and prevent excessive application of adhesive to ensure adhesion. Additionally, in the spinning and stretching process of synthetic fibers, if the synthetic fibers are exposed to high temperatures, burrs may easily form. There is a need to further improve the penetration of the adhesive between the synthetic fibers and the high-temperature burr suppression effect.

[0013] Methods for solving problems

[0014] In order to solve the above-mentioned problems, the inventors conducted research and found that the composition of the treatment agent for synthetic fibers containing the specified compounds is suitable.

[0015] It records various methods for solving the above problems.

[0016] The synthetic fiber treatment agent of Method 1 contains a smoothing agent (A) comprising the following complete ester compound (A1) and the following dicarboxylic acid compound (B), and further contains a nonionic surfactant (C) and an ionic surfactant (D). The aforementioned ionic surfactant (D) comprises at least one selected from sulfonic acid compound (D1) and phosphate ester compound (D2). In the synthetic fiber treatment agent, the content of the aforementioned sulfonic acid compound (D1) is 5% by mass or less, and the content of the aforementioned phosphate ester compound (D2) is 5% by mass or less. The complete ester compound (A1) is a complete ester compound of a polyol with three or more but no more than four members and a monocarboxylic acid. The dicarboxylic acid compound (B) is selected from at least one dicarboxylic acid and its salts having 3 or more but no more than 10 carbon atoms having 0 or more but no more than 1 hydroxyl groups in the molecule.

[0017] Regarding Method 2, in the synthetic fiber treatment agent described in Method 1, the dicarboxylic acid compound (B) has 4 or more and 6 or fewer carbon atoms.

[0018] Regarding method 3, the synthetic fiber treatment agent described in method 1 or 2 contains a dicarboxylic acid constituting the dicarboxylic acid compound (B) in a proportion of 0.01% by mass or more and 1% by mass or less relative to the total mass of the synthetic fiber treatment agent.

[0019] Regarding Method 4, the synthetic fiber treatment agent described in any of Methods 1 to 3 contains the above-mentioned complete ester compound (A1) in a proportion of 25% by mass or more and 70% by mass or less relative to the total mass of the synthetic fiber treatment agent.

[0020] The key feature of the synthetic fiber of method 5 is that it is coated with the synthetic fiber treatment agent described in any of methods 1 to 4.

[0021] Invention Effects

[0022] According to the present invention, the penetration of adhesive between synthetic fibers and the high-temperature burr suppression effect can be improved. Detailed Implementation

[0023] <First Implementation>

[0024] The first embodiment of the synthetic fiber treatment agent (hereinafter also referred to as the treatment agent) of the present invention will be described below.

[0025] The processing agent in this embodiment contains a smoothing agent (A) comprising the following complete ester compound (A1) and the following dicarboxylic acid compound (B).

[0026] Complete ester compounds (A1) are complete ester compounds of polyols with three or more but less than four members and monocarboxylic acids.

[0027] The dicarboxylic acid compound (B) is selected from at least one of dicarboxylic acids and their salts having 3 or more and 10 or fewer carbon atoms having 0 or more and 1 or fewer hydroxyl groups in the molecule.

[0028] By including the above-mentioned smoothing agent (A) and dicarboxylic acid compound (B) in the treatment agent, the penetration of the adhesive between synthetic fibers and the high-temperature burr suppression effect can be improved.

[0029] (Smoothing Agent (A))

[0030] The smoothing agent (A) contains the aforementioned complete ester compound (A1).

[0031] Specific examples of polyols with three or more but less than four members that can be used as raw materials for complete ester compounds (A1) include glycerol, pentaerythritol, trimethylolpropane, 2-methyl-2-hydroxymethyl-1,3-propanediol, 1,2,3-butanetriol, 1,2,4-butanetriol, erythritol, 1,2,3-pentanetriol, 1,2,4-pentanetriol, etc.

[0032] Regarding the monocarboxylic acid used as a starting material for the complete ester compound (A1), known substances can be appropriately used, including both saturated and unsaturated carboxylic acids. Furthermore, it can be a straight-chain monocarboxylic acid or a monocarboxylic acid with a branched structure.

[0033] Specific examples of carboxylic acids include: (1) straight-chain alkyl fatty acids such as octanoic 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, dodecanoic acid, and tetradecanoic acid; (2) branched-chain alkyl fatty acids such as 2-ethylhexanoic acid, isododecanoic acid, isotridecanoic acid, isotetradecanoic acid, isohexadecanoic acid, and isooctadecanoic acid; (3) straight-chain alkenyl fatty acids such as crotonic acid, myristoleic acid, palmitoleic acid, oleic acid, isoleic acid, eicosenoic acid, linoleic acid, α-linolenic acid, γ-linolenic acid, and arachidonic acid; and (4) fatty acids from natural sources such as castor oil fatty acids, sesame oil fatty acids, tall oil fatty acids, soybean oil fatty acids, rapeseed oil fatty acids, palm oil fatty acids, palm kernel fatty acids, and coconut oil fatty acids.

[0034] Specific examples of complete ester compounds (A1) include trimethylolpropane triesters of palm kernel fatty acids, vegetable oils such as rapeseed oil, and pentaerythritol tetraoctanoate.

[0035] These complete ester compounds (A1) can be used alone, or two or more complete ester compounds (A1) can be used in appropriate combinations.

[0036] In addition to containing the aforementioned complete ester compound (A1), the smoothing agent (A) may also contain a smoothing agent (A2) used in the field of processing agents. Examples of smoothing agents (A2) include mineral oil (kinematic viscosity of 5 mm at 40°C). 2 Mineral oils (above / s), polyolefins, ester compounds other than complete ester compounds (A1), etc.

[0037] Examples of mineral oils include aromatic hydrocarbons, alkane hydrocarbons, and cycloalkanes. More specifically, examples include spindle oil and liquid paraffin.

[0038] Polyolefins can be used as smoothing agents, such as poly-α-olefins. Specific examples of polyolefins include poly-α-olefins obtained by polymerizing 1-butene, 1-hexene, 1-decene, etc. Commercially available poly-α-olefins may be appropriately used.

[0039] Specific examples of smoothing agents (A2) include diisoceryl adipate, oleic acid oleate, and di(oleyl) thiodipropionate.

[0040] Of the above-mentioned smoothing agents (A), one smoothing agent (A) may be used alone, or two or more smoothing agents (A) may be used in appropriate combination.

[0041] In the treatment agent, the lower limit of the content of the complete ester compound (A1) relative to the total mass of the treatment agent is preferably 25% by mass or more, more preferably 30% by mass or more. The upper limit of the content of the complete ester compound (A1) relative to the total mass of the treatment agent is preferably 80% by mass or less, more preferably 70% by mass or less. It should be noted that any combination of the above upper and lower limits is also acceptable. If the content of the complete ester compound (A1) is within the above-mentioned numerical range, the high-temperature burr suppression effect can be further improved.

[0042] (Dicarboxylic acid compound (B))

[0043] The dicarboxylic acid compound (B) is selected from at least one of dicarboxylic acids and their salts having 3 or more and 10 or fewer carbon atoms having 0 or more and 1 or fewer hydroxyl groups in the molecule.

[0044] As a dicarboxylic acid having 3 to 10 carbon atoms and 0 to 1 hydroxyl groups in its molecule, it can appropriately use known substances, and can be either saturated or unsaturated carboxylic acids. It can be either aliphatic or aromatic carboxylic acids. Examples of dicarboxylic acids with 3 to 10 carbon atoms include malonic acid, succinic acid, oxosuccinic acid (malic acid), glutaric acid, adipic acid, fumaric acid, maleic acid, and other aliphatic carboxylic acids, as well as aromatic carboxylic acids such as terephthalic acid and isophthalic acid.

[0045] Examples of salts of the aforementioned dicarboxylic acids include alkali metal salts, amine salts, and phosphonium salts.

[0046] Examples of alkali metals that can form the aforementioned alkali metal salts include sodium and potassium.

[0047] Examples of amines that form the above-mentioned amine salts include (1) aliphatic amines such as methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, butylamine, dibutylamine, tributylamine, and octylamine; (2) aromatic amines or heterocyclic amines such as aniline, pyridine, morpholine, piperazine, and their derivatives; (3) alkyl alcohol amines such as monoethanolamine, diethanolamine, triethanolamine, isopropanolamine, diisopropanolamine, triisopropanolamine, butyl diethanolamine, octyl diethanolamine, (poly)oxyalkylene alkylamine salts, and lauryl diethanolamine; (4) ammonia; and so on.

[0048] Examples of phosphorus groups that form the aforementioned phosphonium salts include: (1) phosphorus groups such as tetramethylphosphonium, tetraethylphosphonium, tetrabutylphosphonium, trimethylethylphosphonium, trimethylpropylphosphonium, trimethyloctylphosphonium, trimethyldodecylphosphonium, and trimethyloctadecylphosphonium, where all organic groups bonded to the phosphorus atom are aliphatic hydrocarbon groups; (2) phosphorus groups such as trimethylphenylphosphonium, triethylphenylphosphonium, tributylphenylphosphonium, dimethyldiphenylphosphonium, triphenylethylphosphonium, and tetraphenylphosphonium, where at least one of the organic groups bonded to the phosphorus atom is an aromatic hydrocarbon group; and so on. When water is generated during neutralization, it can be mixed with the treatment agent, or the water can be removed before mixing with the treatment agent. Alternatively, the neutralized dicarboxylic acid product prepared beforehand can be mixed with the treatment agent, or neutralization can be carried out in the treatment agent. When mixing dicarboxylic acid compounds with treatment agents, they can be mixed with the compatibilizer first and then with the treatment agent.

[0049] Specific examples of dicarboxylic acid compounds (B) include substances obtained by neutralizing adipic acid with 4 moles of ethylene oxide in a 1:1 mol ratio (hereinafter also called adipic acid laurylamine EO4 salt), fumaric acid, malic acid, dipotassium malonicate (a substance obtained by neutralizing and dehydrating malonic acid with potassium hydroxide in a 1:2 mol ratio), and dipotassium sebate (a substance obtained by neutralizing and dehydrating sebate with potassium hydroxide in a 1:2 mol ratio).

[0050] These dicarboxylic acid compounds (B) can be used alone, or two or more dicarboxylic acid compounds (B) can be used in appropriate combinations.

[0051] The dicarboxylic acid compound (B) preferably has 4 or more and 6 or fewer carbon atoms. If the dicarboxylic acid compound (B) has 4 or more and 6 or fewer carbon atoms, the high-temperature burr suppression effect can be further improved.

[0052] The lower limit of the proportion of dicarboxylic acid constituting dicarboxylic acid compound (B) relative to the total mass of the treatment agent is preferably 0.01% by mass or more, more preferably 0.1% by mass or more. The upper limit of the proportion of dicarboxylic acid relative to the total mass of the treatment agent is preferably 1% by mass or less, more preferably 0.6% by mass or less. It should be noted that any combination of the above upper and lower limits is also acceptable.

[0053] Here, the "content ratio of dicarboxylic acid constituting dicarboxylic acid compound (B)" refers to the amount of dicarboxylic acid in dicarboxylic acid compound (B) when the counter ion becomes hydrogen. That is, in the case that dicarboxylic acid compound (B) is a potassium salt of dicarboxylic acid, it refers to the content ratio of dicarboxylic acid in which potassium is replaced by hydrogen.

[0054] By ensuring the dicarboxylic acid content falls within the aforementioned range, the effects of the present invention can be more effectively demonstrated. The dicarboxylic acid content can be calculated based on the mixing amounts of each raw material during the preparation of the treatment agent. Alternatively, it can be determined using the liquid chromatography-mass spectrometry method described later.

[0055] (Nonionic surfactant (C))

[0056] The treatment agent may further contain a nonionic surfactant (C). By including a nonionic surfactant (C) in the treatment agent, the appearance stability of the treatment agent can be improved. In addition, as a diluent when coating synthetic fibers, solvents with different polarities, such as water and / or organic solvents, can be used.

[0057] Examples of nonionic surfactants (C) include compounds having a (poly)oxyalkylene structure formed by adding an epoxide to alcohols or carboxylic acids; ether / ester compounds having a (poly)oxyalkylene structure formed by adding an epoxide to an ester compound of a carboxylic acid and a polyol; compounds formed by adding an epoxide to natural oils or by esterifying such compounds with carboxylic acids; compounds having a (poly)oxyalkylene structure formed by adding an epoxide to an amine compound, such as an organic primary amine; compounds having a (poly)oxyalkylene structure formed by adding an epoxide to a fatty amide; amide compounds formed by condensing an amine compound with a carboxylic acid; and esterified compounds of carboxylic acids and polyols.

[0058] Specific examples of alcohols used as raw materials for nonionic surfactants (C) include: (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, eicosane, dodecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, hexadecanol, heptadecanol, octadecanol, nonadecanol, and triacontanol; and (2) isopropanol, isobutanol, isohexanol, 2-ethylhexanol, isononanol, isodecanol, isodecanol, isodecanol, isodecanol, isodecanol, and isotriacontanol. Branched alkyl alcohols such as alcohols, isohexadecanol, isohexadecanol, isohexadecanol, isohexadecanol, isohexadecanol, isohexadecanol, isohexadecanol, isohexadecanol, isohexadecanol, isohexadecanol, isohexadecanol, isohexadecanol, isohexadecanol, isohexadecanol, isohexadecanol, isohexadecanol, isohexadecanol, isohexadecanol, etc.; (3) Straight-chain alkenyl alcohols such as tetradecenol, hexadecenol, heptadecenol, octadecenol, and nonadecenol; (4) Branched alkenyl alcohols such as isohexadecanol and isohexadecanol; (5) Cyclic alkyl alcohols such as cyclopentanol and cyclohexanol; (6) Aromatic alcohols such as phenol, nonylphenol, benzyl alcohol, monostyrene phenol, stilbene phenol, and tristyrene phenol.

[0059] Specific examples of carboxylic acids used as raw materials for nonionic surfactants (C) include: (1) straight-chain alkyl carboxylic acids such as octanoic 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, dodecanoic acid, etc.; (2) branched-chain alkyl carboxylic acids such as 2-ethylhexanoic acid, isododecanoic acid, isotridecanoic acid, isotetradecanoic acid, isohexadecanoic acid, etc.; (3) straight-chain alkenyl carboxylic acids such as octadecenoic acid, octadecadienoic acid, octadectrienoic acid, etc.; (4) aromatic carboxylic acids such as benzoic acid; (5) hydroxycarboxylic acids such as ricinoleic acid; etc.

[0060] Regarding the epoxide used as a raw material for forming the (poly)oxyalkylene structure of the nonionic surfactant (C), epoxides with 2 or more and 4 or fewer carbon atoms are preferred. Specific examples of epoxides include ethylene oxide, propylene oxide, and butane oxide. The molar number of epoxides added can be appropriately set, preferably 0.1 moles or more and 250 moles or less, more preferably 1 mole or more and 200 moles or less, and even more preferably 2 moles or more and 150 moles or less. It is also permissible to assume a range formed by any combination of the above upper and lower limits. It should be noted that the molar number of epoxides added represents the number of moles of epoxide relative to 1 mole of the target compound in the loaded raw material. An epoxide can be used alone, or two or more epoxides can be used in appropriate combinations. When using two or more epoxides, their addition mode can be any of block addition, random addition, and a combination of block addition and random addition, without particular limitation.

[0061] Specific examples of polyols used as raw materials for nonionic surfactants (C) 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, glycerol, diglycerol, 2-methyl-2-hydroxymethyl-1,3-propanediol, trimethylolpropane, sorbitan, pentaerythritol, sorbitol, etc.

[0062] Specific examples of aliphatic or organic primary amines used as raw materials for nonionic surfactants (C) include methylamine, ethylamine, butylamine, octylamine, laurylamine, stearylamine, octadeceneamine, and coconutamine.

[0063] Specific examples of fatty amides used as raw materials for nonionic surfactants (C) include octamide, lauramide, palmitamide, stearamide, oleamide, behenamide, and wood wax amide.

[0064] Specific examples of nonionic surfactants (C) include substances formed by adding 8 moles of ethylene oxide (hereinafter referred to as EO) to 1 mole of oleyl alcohol; substances formed by adding 12 moles of propylene oxide (hereinafter referred to as PO) to 1 mole of isotridecyl alcohol; substances formed by adding 10 moles of EO to 1 mole of hydrogenated castor oil; compounds formed by esterifying a substance formed by adding 25 moles of EO to 1 mole of hydrogenated castor oil with 2 moles of oleic acid; compounds formed by crosslinking a substance formed by adding 20 moles of EO to 1 mole of hydrogenated castor oil with adipic acid and then terminally esterifying it with stearic acid (mass average molecular weight 5000); substances formed by adding 8 moles of EO to 1 mole of sorbitan monolaurate or sorbitan monooleate; diesters of polyethylene glycol (mass average molecular weight 400) and oleic acid; substances formed by adding 8 moles of EO to 1 mole of laurylamine; and substances formed by adding 3 moles of EO to 1 mole of oleic acid diethanolamide.

[0065] These nonionic surfactants (C) can be used alone, or two or more nonionic surfactants (C) can be used in appropriate combinations.

[0066] The lower limit of the content of nonionic surfactant (C) in the treatment agent is preferably 20% by mass or more, more preferably 30% by mass or more. Furthermore, the upper limit of the content of this nonionic surfactant (C) is preferably 90% by mass or less, more preferably 80% by mass or less. It should be noted that any combination of the above upper and lower limits is also acceptable.

[0067] By maintaining the content of the nonionic surfactant (C) within the aforementioned range, the appearance stability of the treatment agent can be further improved. Furthermore, as a diluent for coating synthetic fibers, solvents with different polarities, such as water and organic solvents, are more readily applicable.

[0068] (Ionic surfactant (D))

[0069] The treatment agent may further contain an ionic surfactant (D). By including an ionic surfactant (D) in the treatment agent, static electricity generated in the synthetic fibers coated with the treatment agent when passing through the stretching rollers or yarn guides can be suppressed during the spinning and stretching process of the synthetic fibers.

[0070] Examples of ionic surfactants (D) include anionic surfactants, cationic surfactants, and amphoteric surfactants.

[0071] As anionic surfactants, known substances can be appropriately used. Specific examples of anionic surfactants include: (1) phosphate salts of aliphatic alcohols such as lauryl phosphate, cetyl phosphate, octyl phosphate, oleyl phosphate, and stearyl phosphate; (2) phosphate salts of substances formed by the addition of aliphatic alcohols to at least one epoxide selected from ethylene oxide and propylene oxide, such as polyoxyethylene lauryl ether phosphate, polyoxyethylene oleyl ether phosphate, and polyoxyethylene stearyl ether phosphate; (3) aliphatic sulfonates or aromatic sulfonates such as lauryl sulfonate, myristyl sulfonate, cetyl sulfonate, oleyl sulfonate, stearyl sulfonate, tetradecyl sulfonate, dodecylbenzene sulfonate, secondary alkyl sulfonic acid (13 or more carbon atoms and less than 15 carbon atoms) salts, secondary alkyl sulfonic acid (11 or more carbon atoms and less than 14 carbon atoms) salts, and α-olefin sulfonates; (4) lauryl sulfate, oleyl sulfate, stearyl sulfate, etc. (5) Sulfate salts of aliphatic alcohols such as ester salts; (6) Sulfate salts of fatty acids such as castor oil fatty acid sulfate salts, sesame oil fatty acid sulfate salts, tall oil fatty acid sulfate salts, soybean oil fatty acid sulfate salts, rapeseed oil fatty acid sulfate salts, and palm oil fatty acid sulfate salts; (7) Sulfate salts of oils such as castor oil sulfate salts, sesame oil sulfate salts, tall oil sulfate salts, soybean oil sulfate salts, rapeseed oil sulfate salts, and palm oil sulfate salts; (8) Fatty acid salts such as laurate, oleate, and stearate; (9) Sulfonated succinate salts of aliphatic alcohols such as dioctyl sulfonated succinate; etc. Counterions for anionic surfactants include, for example, alkali metal salts such as potassium and sodium salts, ammonium salts, triethanolamine salts, (poly)oxyalkylene alkylamine salts, and alkylolamine salts such as dibutylethanolamine salts.

[0072] As an anionic surfactant, from the perspective of further improving the high-temperature burr suppression effect, it is preferable to include at least one of the sulfonate salt selected from (3) above and the phosphate salt selected from (1) or (2) above. It should be noted that the sulfonate salt and the phosphate salt are also referred to as sulfonic acid compound (D1) and phosphate salt (D2), respectively.

[0073] Ionic surfactants (D) can further enhance the high-temperature burr suppression effect by including at least one selected from sulfonic acid compounds (D1) and phosphate ester compounds (D2).

[0074] Specific examples of sulfonic acid compounds (D1) include sodium salts of secondary alkane sulfonates (substances of alkanes with 11 or more but less than 14 carbon atoms), sodium salts of di(2-ethylhexyl)sulfonated succinate, sodium salts of α-olefin sulfonates, etc.

[0075] Specific examples of phosphate ester compounds (D2) include, for example, the phosphate ester-triethanolamine salt of oleyl alcohol EO6 molar adduct and the isocetyl phosphate-dibutylethanolamine salt.

[0076] Anionic surfactants may also contain anionic surfactants (D3) other than sulfonic acid compounds (D1) and phosphate ester compounds (D2). Specific examples of anionic surfactants (D3) include sodium lauryl sulfate.

[0077] These anionic surfactants can be used alone, or two or more anionic surfactants can be used in appropriate combinations.

[0078] Specific examples of cationic surfactants include lauryltrimethylammonium chloride, cetyltrimethylammonium chloride, stearyltrimethylammonium chloride, docosyltrimethylammonium chloride, and dialcyldimethylammonium chloride.

[0079] Specific examples of amphoteric surfactants include betaine-type amphoteric surfactants.

[0080] These ionic surfactants (D) can be used alone, or two or more ionic surfactants (D) can be used in appropriate combinations.

[0081] In the treatment agent, the lower limit of the content of the ionic surfactant (D) is preferably 1% by mass or more, more preferably 3% by mass or more. Furthermore, the upper limit of the content of the ionic surfactant (D) is preferably 10% by mass or less, more preferably 6% by mass or less. It should be noted that any combination of the above upper and lower limits is also acceptable.

[0082] In the treatment agent, the lower limit of the content of the sulfonic acid compound (D1) is preferably 0.1% by mass or more, more preferably 0.5% by mass or more. Furthermore, the upper limit of the content of the sulfonic acid compound (D1) is preferably 5% by mass or less, more preferably 3% by mass or less. It should be noted that any combination of the above upper and lower limits is also acceptable.

[0083] In the treatment agent, the lower limit of the content of the phosphate ester compound (D2) is preferably 1% by mass or more, more preferably 1.5% by mass or more. Furthermore, the upper limit of the content of the phosphate ester compound (D2) is preferably 5% by mass or less, more preferably 3% by mass or less. It should be noted that any combination of the above upper and lower limits is also acceptable.

[0084] By setting the content of sulfonic acid compound (D1), phosphate ester compound (D2), or ionic surfactant (D) within the above-mentioned numerical range, static electricity generated when synthetic fibers coated with the treatment agent pass through stretching rollers or yarn guides can be more effectively suppressed.

[0085] (Other ingredients (E))

[0086] The treatment agent may further contain other components (E). There are no particular limitations on these other components; examples include ethylene glycol, diethylene glycol, polyethylene glycol, polypropylene glycol, glycerin, polyether-modified silicone, dimethylpolysiloxane, and 6-(4-hydroxy-3,5-di-tert-butylaniline)-2,4-bis(octylthio)-1,3,5-triazine. Furthermore, from the perspective of improving the stability of appearance during storage, the treatment agent can be pre-mixed with water. In this case, the mixing ratio of the treatment agent to water is preferably (mass of treatment agent / mass of water) = 85 / 15 to 99.9 / 0.1.

[0087] <Second Implementation Method>

[0088] Next, a second embodiment embodying the synthetic fiber based on the present invention will be described. In this embodiment, the synthetic fiber is coated with the treatment agent of the first embodiment. The form of the treatment agent used to coat the synthetic fiber can be a diluted solution diluted with a diluent, such as an organic solvent solution or an aqueous solution. From the perspective of the adhesion of the treatment agent to the fiber and economy, hydrocarbons with 10 or more but less than 15 carbon atoms and water are preferred as diluents. Aqueous solutions and other diluents are coated onto the synthetic fiber, for example, during spinning or stretching processes. The diluent coated onto the synthetic fiber can be evaporated by stretching or drying processes. There are no particular limitations on the process in which the diluent is coated, as long as it is a spinning process. In stretching or heat treatment processes, the effects of the invention are more likely to be achieved by using manufacturing equipment that allows the fiber to pass through rollers at temperatures of 200°C or higher.

[0089] There are no particular limitations on specific examples of synthetic fibers to which the treatment agent of this embodiment is applied, and examples include: (1) polyester fibers such as polyethylene terephthalate, polyethylene terephthalate, polyethylene terephthalate, polyethylene naphthalate, polylactic acid, and composite fibers containing these polyester resins; (2) polyamide fibers such as nylon 6 and nylon 66; (3) polyacrylic acid fibers such as polyacrylic acid and modified acrylic acid; (4) polyolefin fibers such as polyethylene and polypropylene; and so on. Among these, polyester fibers and polyamide fibers are preferred.

[0090] There are no particular limitations on the proportion of the treatment agent adhering to the synthetic fiber, but it is preferable that the treatment agent is adhering at a proportion of 0.1% to 3% by mass relative to the synthetic fiber (excluding the proportion of solvents such as water). This configuration further enhances the effectiveness of the present invention. Furthermore, there are no particular limitations on the method of adhering the treatment agent; for example, known methods such as roller oiling, guided oiling using a metering pump, impregnation oiling, and spray oiling can be employed.

[0091] In this invention, the use of synthetic fibers is not particularly limited, but synthetic fibers used in industrial materials are preferred. For example, synthetic fibers used in the automotive, construction, commercial, agricultural and fisheries, and civil engineering fields, such as airbag fibers, seat belt fibers, tire cord fibers, carpet fibers, tent fibers, advertising fabric fibers, fishing net fibers, conveyor belt fibers, and rope fibers, are more preferred.

[0092] When the aforementioned industrial materials are used as reinforcing materials for rubber products, there are no particular limitations on the adhesive used for bonding with rubber materials. Known adhesives for bonding with rubber materials can be used. Examples of known adhesives for bonding with rubber materials include epoxy compounds, isocyanate compounds, and resorcinol-formaldehyde-latex (RFL) solutions. Among these, epoxy compounds are preferred. Mixtures of these adhesives and mixtures of adhesives and surfactants are also possible. Furthermore, when applying the adhesive, a solution diluted with water or an organic solvent can be used, or the adhesive can be applied in its original state.

[0093] There are no particular limitations on the process by which the treatment agent and adhesive of the present invention are attached to synthetic fibers.

[0094] For example, during yarn making, a treatment agent is applied to synthetic fibers, and then the twisted yarn of the synthetic fibers is woven to produce a fabric. An adhesive can be applied to this fabric to bond it to a rubber material. Alternatively, the treatment agent and adhesive can be pre-mixed to create a mixture. After applying the mixture to the synthetic fibers during yarn making, the twisted yarn of the synthetic fibers is woven to produce a fabric. This fabric can be bonded to a rubber material. Alternatively, during yarn making, the treatment agent and adhesive are separately applied to the synthetic fibers, and then the twisted yarn of the synthetic fibers is woven to produce a fabric. This fabric can be bonded to a rubber material. Furthermore, bonding to rubber materials can be performed not only on the fabric but also on the raw yarn and the twisted yarn. When applying the adhesive to the raw yarn, it can be done before or after stretching. After yarn making, the adhesive can be applied and the yarn can be rewound.

[0095] <Effect>

[0096] The effects of the treatment agent and synthetic fiber in the above embodiments will be explained.

[0097] (1) The processing agent of the above embodiment contains a smoothing agent (A) comprising the following complete ester compound (A1) and the following dicarboxylic acid compound (B).

[0098] A complete ester compound (A1) is a complete ester compound of a polyol with three or more but no more than four members and a monocarboxylic acid. A dicarboxylic acid compound (B) is selected from at least one of dicarboxylic acids and their salts having 3 or more but no more than 10 carbon atoms having 0 or more but no more than 1 hydroxyl groups in the molecule.

[0099] Therefore, it can improve the penetration of adhesives between synthetic fibers and the effect of inhibiting high-temperature burrs.

[0100] (2) The dicarboxylic acid compound (B) has 4 or more but less than 6 carbon atoms. Therefore, it can further improve the high-temperature burr suppression effect.

[0101] (3) The treatment agent contains a dicarboxylic acid constituting the dicarboxylic acid compound (B) in a proportion of 0.01% by mass or more and 1% by mass or less relative to the total mass of the treatment agent. Therefore, the effects of the present invention can be exhibited more effectively.

[0102] (4) The treatment agent contains a complete ester compound (A1) at a ratio of 25% to 70% by mass relative to the total mass of the treatment agent. Therefore, it can further improve the high-temperature burr suppression effect.

[0103] (5) The treatment agent contains both nonionic surfactant (C) and ionic surfactant (D). Therefore, the appearance stability of the treatment agent can be improved. Furthermore, as a diluent for coating synthetic fibers, solvents with different polarities, such as water and / or organic solvents, can be used. Additionally, static electricity generated on synthetic fibers coated with the treatment agent when passing through stretching rollers or yarn guides can be suppressed.

[0104] (6) By including at least one of sulfonic acid compound (D1) and phosphate ester compound (D2) in the ionic surfactant (D), the high-temperature burr suppression effect can be further improved.

[0105] <Example of Change>

[0106] It should be noted that the above implementation methods can also be modified as follows. The above implementation methods and the following modifications can be combined with each other to implement them within the scope of technical inconsistency.

[0107] • In the treatment agent of the above embodiments, without hindering the effect of the present invention, stabilizers, charge control agents, binders, antioxidants, ultraviolet absorbers, defoamers, preservatives, rust inhibitors and other components commonly used in treatment agents may be further mixed in during or after the manufacturing of the treatment agent to maintain the quality of the treatment agent.

[0108] The processing agent in the above embodiments may not necessarily contain the nonionic surfactant (C) and ionic surfactant (D) described above. Alternatively, the processing agent may contain both nonionic surfactant (C) and ionic surfactant (D), or it may contain only one of nonionic surfactant (C) and ionic surfactant (D).

[0109] • In the processing agent of the above embodiments, the ionic surfactant (D) may also be a substance other than sulfonic acid compound (D1) and phosphate ester compound (D2).

[0110] • Other components (E) may be omitted in the processing agent of the above embodiments.

[0111] Example

[0112] To illustrate the structure and effects of the present invention more specifically, embodiments are given below, but the present invention is not limited to these embodiments. It should be noted that, unless otherwise stated, in the following descriptions of embodiments and comparative examples, parts refer to parts by mass, and % refers to percentages by mass.

[0113] Experimental Group 1 (Preparation of the Treatment Agent)

[0114] (Example 1)

[0115] As shown in Table 1, the treatment agent of Example 1 containing the following components was prepared: 40 parts (%) of trimethylolpropane and palm kernel fatty acid triester (A1-1), which is a complete ester compound (A1) belonging to the smoothing agent (A); 20 parts (%) of pentaerythritol tetraoctanoate (A1-3); 0.1 parts (%) of lauryl adipic acid EO4 salt (B-1), which is a dicarboxylic acid compound (B); 10 parts (%) of a substance formed by adding 1 mole of PO to 12 moles of isotriadecyl alcohol to 1 mole of EO to 12 moles of other substances, which is a nonionic surfactant (C); and 10 parts (%) of a substance formed by adding 1 mole of EO to 1 mole of hydrogenated castor oil to 10 moles of other substances. The following compounds were included: 14 parts (%) of compound (C-4) formed by esterification of a substance obtained by adding 25 moles of EO to 1 mole of hydrogenated castor oil with 2 moles of oleic acid; 2 parts (%) of substance (C-9) formed by adding 8 moles of EO to 1 mole of laurylamine; 1.85 parts (%) of sodium secondary alkane sulfonate (a substance with 11 or more and 14 or less carbon atoms in an ionic surfactant (D)); 2 parts (%) of isohexadecanophosphate-dibutylethanolamine salt (D2-2) formed as a phosphate ester compound (D2); and 0.05 parts (%) of dimethylpolysiloxane (E-2) formed as other components (E).

[0116] (Examples 2-11, Comparative Examples 1-5)

[0117] The treatment agents of Examples 2-11 and Comparative Examples 1-5 were prepared in the same manner as the treatment agent of Example 1, comprising a smoothing agent (A), a dicarboxylic acid compound (B), a nonionic surfactant (C), an ionic surfactant (D), and other components (E) in the proportions shown in Table 1.

[0118] The types and contents of smoothing agents (A), dicarboxylic acid compounds (B), nonionic surfactants (C), ionic surfactants (D), and other components (E) are listed in the "Smoothing Agents (A)", "Dicarboxylic Acid Compounds (B)", "Nonionic Surfactants (C)", "Ionic Surfactants (D)" and "Other Components (E)" columns of Table 1, respectively.

[0119] [Table 1]

[0120]

[0121] The details of the smoothing agent (A), dicarboxylic acid compound (B), nonionic surfactant (C), ionic surfactant (D), and other components (E) listed in Table 1 are as follows.

[0122] <Smoothing Agent (A)>

[0123] (Complete ester compound (A1))

[0124] A1-1: Triester of trimethylolpropane and palm kernel fatty acids

[0125] A1-2: Rapeseed oil

[0126] A1-3: Pentaerythritol tetraoctanoate

[0127] (Smoothing agents other than A1 (A2))

[0128] A2-1: Diisoceryl adipic acid

[0129] A2-2: Oleic acid ester

[0130] A2-3: Di(oleyl) thiodipropionate

[0131] <Dicarboxylic acid compound (B)>

[0132] B-1: Adipic acid laurylamine EO4 salt (a substance obtained by neutralizing adipic acid with 4 moles of ethylene oxide at a ratio of 1 mole to 1 mole of laurylamine in a 1:1 mol ratio)

[0133] B-2: Fumaric acid

[0134] B-3: Malic acid

[0135] B-4: Dipotassium malonate (a substance obtained by neutralizing and dehydrating malonic acid and potassium hydroxide in a 1:2 mol ratio)

[0136] B-5: Dipotassium sebacate (a substance obtained by neutralizing and dehydrating sebacate and potassium hydroxide in a 1:2 mol ratio).

[0137] <Carboxylic acid compounds (rB) that are different from dicarboxylic acid compound (B)>

[0138] rB-1: Dipotassium dodecenylsuccinate (a substance obtained by neutralizing and dehydrating dodecenylsuccinate with potassium hydroxide at a ratio of 1:2 mol)

[0139] rB-2: Triethanolamine tartrate (a substance obtained by neutralizing tartaric acid and triethanolamine in a 1:2 mol ratio)

[0140] rB-3: Potassium oleate (a substance obtained by neutralizing and dehydrating oleic acid with potassium hydroxide in a 1:1 mol ratio).

[0141] <Nonionic Surfactant (C)>

[0142] C-1: A substance formed by adding 1 mole of oleyl alcohol to 8 moles of EO.

[0143] C-2: A substance formed by adding 1 mole of PO to 12 moles of a substance relative to 1 mole of isotredecyl alcohol, and then adding 12 moles of EO.

[0144] C-3: A substance formed by adding 10 moles of EO to 1 mole of hydrogenated castor oil.

[0145] C-4: A compound obtained by esterification of a substance formed by adding 25 moles of EO relative to 1 mole of hydrogenated castor oil with 2 moles of oleic acid.

[0146] C-5: A compound (mass average molecular weight 5000) formed by cross-linking a substance obtained by adding 20 moles of EO relative to 1 mole of hydrogenated castor oil, cross-linking it with adipic acid, and terminally esterifying it with stearic acid.

[0147] C-6: Sorbitan monolaurate

[0148] C-7: A substance formed by adding 1 mole of p-sorbitan monooleate to 8 moles of EO.

[0149] C-8: Diester of polyethylene glycol (mass average molecular weight 400) and oleic acid

[0150] C-9: A substance formed by adding 1 mole of laurylamine to 8 moles of E0.

[0151] C-10: A substance formed by adding 3 moles of EO to 1 mole of oleic acid diethanolamide.

[0152] <Ionic Surfactants (D)>

[0153] (Sulfonic acid compound (D1))

[0154] D1-1: Sodium salt of secondary alkane sulfonate (substances of alkanes with 11 or more but less than 14 carbon atoms)

[0155] D1-2: Sodium di(2-ethylhexyl)sulfonated succinate

[0156] D1-3: Sodium α-olefin sulfonate

[0157] (Phosphate compound (D2))

[0158] D2-1: Phosphate-triethanolamine salt of oleyl alcohol EO6 molar adduct

[0159] D2-2: Isoceridyl phosphate-dibutylethanolamine salt

[0160] (Ionic surfactants other than D1 and D2 (D3))

[0161] D3-1: Sodium lauryl sulfate

[0162] <Other Ingredients (E)>

[0163] E-1: Polyether-modified silicone

[0164] E-2: Dimethylpolysiloxane

[0165] E-3: 6-(4-hydroxy-3,5-di-tert-butylaniline)-2,4-bis(octylthio)-1,3,5-triazine

[0166] <Method for determining the proportion of dicarboxylic acids>

[0167] The proportion of dicarboxylic acid constituting dicarboxylic acid compound (B) relative to the total mass of the treatment agent can be determined by liquid chromatography-mass spectrometry (hereinafter referred to as LC / MS).

[0168] The LC / MS determination was performed under the following conditions.

[0169] Liquid chromatography (LC)

[0170] Device used: UPLC H-Class manufactured by Waters Corporation

[0171] Analytical column: Shodex RSpak DE-213 (2.0 mm inner diameter × 150 mm length)

[0172] Column temperature: 40℃

[0173] Mobile phase A: 0.1% (w / w) formic acid ultrapure aqueous solution

[0174] Mobile phase B: 0.1% (w / w) formic acid acetonitrile solution

[0175] Gradient conditions: 0 minutes (A / B = 95 vol%) → 5 minutes (A / B = 95 vol%) → 20 minutes (A / B = 5 vol%) → 30 minutes (A / B = 5 vol%)

[0176] Flow rate: 0.2 mL / min

[0177] Mass spectrometry (MS)

[0178] Device used: Waters SQD2

[0179] Ionization mode: ESI SIM Negative

[0180] A calibration curve was prepared using the dicarboxylic acid compound (B) used in the treatment agent as a standard, and the amount of dicarboxylic acid in the treatment agent was determined. The results are shown in the "Ratio of Dicarboxylic Acid to Total Mass of Treatment Agent" column of Table 1. The determined amount of dicarboxylic acid is approximately the same as the amount calculated based on the mixing amount of dicarboxylic acid compound (B) used in the preparation of the treatment agent.

[0181] Experimental Group 2 (Evaluation of High-Temperature Burr Suppression Effect)

[0182] Each synthetic fiber prepared was diluted with a treatment agent using deionized water to prepare a 15% solution. This solution was then applied to 1000 dtex, 126 filament, intrinsic viscosity 0.93 un-oiled polyethylene terephthalate (PET) fibers using a yarn guide oiling method at a rate of 0.6% by mass (based on non-volatile components). The PET fibers coated with the solution were brought into contact with a chrome-plated support bar at a surface temperature of 220°C under initial tension of 1.5 kg and a yarn speed of 300 m / min. The number of burrs on the fibers after contact with the support bar was measured every 10 minutes using a burr counting device (manufactured by Toray Engineering Co., Ltd.), and evaluated according to the following evaluation criteria. The results are shown in the "High-Temperature Burrs" column of Table 1.

[0183] It should be noted that, in this invention, the "high temperature" in the high temperature burr suppression effect refers to temperatures above 200°C.

[0184] Evaluation criteria for high-temperature burr suppression effect

[0185] ◎◎ (Excellent): Case with fewer than 5 burrs

[0186] ◎(Good): The number of burrs is 5 or more but less than 8.

[0187] ○ (Pass): 8 or more but less than 10 burrs

[0188] × (Unacceptable): Cases with more than 10 burrs

[0189] Experimental Group 3 (Evaluation of Permeability)

[0190] Each synthetic fiber prepared was diluted with a treatment agent using deionized water to prepare a 10% solution. Polyglycerol polyglycidyl ether, an epoxy compound, was added to this solution at a concentration of 5%, as a known adhesive. The solutions were mixed to prepare an aqueous solution. A pre-washed polyester fabric was prepared. 5 μL of the prepared aqueous solution was added dropwise to the polyester fabric. The aqueous solution on the polyester fabric was visually confirmed. The aqueous solution initially appeared as droplets, but these droplets disappeared as the solution permeated into the polyester fabric. The time until the droplets disappeared was measured and evaluated according to the following evaluation criteria. The results are shown in the "Permeability" column of Table 1.

[0191] • Evaluation criteria for permeability

[0192] ○ (Pass): Less than 280 seconds

[0193] × (Failure): Cases lasting more than 280 seconds

[0194] It should be noted that the permeability evaluation was performed using polyglycerol polyglycidyl ether and polyester taffeta, but the effects of the present invention are not limited to the use of polyglycerol polyglycidyl ether and polyester taffeta. Polyglycerol polyglycidyl ether and polyester taffeta were used for convenience when evaluating the permeability of the adhesive relative to synthetic fibers.

[0195] As shown in Table 1, the high-temperature burr suppression effect and permeability evaluation of the treatment agents in each embodiment are all above acceptable. According to the present invention, the permeability of the adhesive between synthetic fibers and the high-temperature burr suppression effect can be improved.

[0196] This disclosure also includes the following methods.

[0197] (Postscript 1)

[0198] A treatment agent for synthetic fibers, characterized in that it contains a smoothing agent (A) comprising the following complete ester compound (A1) and the following dicarboxylic acid compound (B).

[0199] Complete ester compounds (A1): Complete ester compounds of polyols with three or more but less than four members and monocarboxylic acids.

[0200] Dicarboxylic acid compound (B): selected from at least one of dicarboxylic acids and their salts having 3 or more and 10 or fewer carbon atoms having 0 or more and 1 or fewer hydroxyl groups in the molecule.

[0201] (Postscript 2)

[0202] According to the synthetic fiber treatment agent described in Appendix 1, the dicarboxylic acid compound (B) has 4 or more and 6 or fewer carbon atoms.

[0203] (Note 3)

[0204] According to the synthetic fiber treatment agent described in Appendix 1, the dicarboxylic acid constituting the dicarboxylic acid compound (B) is contained in a proportion of 0.01% by mass or more and 1% by mass or less relative to the total mass of the synthetic fiber treatment agent.

[0205] (Postscript 4)

[0206] According to Appendix 1, the synthetic fiber treatment agent contains the above-mentioned complete ester compound (A1) in a proportion of 25% by mass or more and 70% by mass or less relative to the total mass of the synthetic fiber treatment agent.

[0207] (Note 5)

[0208] According to Appendix 1, the synthetic fiber treatment agent further contains a nonionic surfactant (C) and an ionic surfactant (D).

[0209] (Note 6)

[0210] According to the synthetic fiber treatment agent described in Appendix 5, the aforementioned ionic surfactant (D) comprises at least one selected from sulfonic acid compound (D1) and phosphate ester compound (D2).

[0211] (Note 7)

[0212] A synthetic fiber, characterized in that it is coated with any one of the synthetic fiber treatment agents described in Appendix 1 to 6.

Claims

1. A treatment agent for synthetic fibers, characterized by, containing a smoothing agent (A) containing a per-ester compound (Al) described below, and a dicarboxylic acid compound (B) described below, further containing a nonionic surfactant (C) and an ionic surfactant (D), the ionic surfactant (D) contains at least one selected from a sulfonic acid compound (Dl) and a phosphate ester compound (D2), the sulfonic acid compound (Dl) is contained at a ratio of 5 mass% or less, and the phosphate ester compound (D2) is contained at a ratio of 5 mass% or less, the per-ester compound (Al) is a per-ester compound of a polyhydric alcohol of three or more and four or less valences and a monovalent carboxylic acid, the dicarboxylic acid compound (B) is at least one selected from dicarboxylic acids and salts thereof having 3 or more and 10 or less carbon atoms and 0 or more and 1 or less hydroxyl groups in the molecule, with respect to the total mass of the treatment agent for synthetic fibers, the per-ester compound (Al) is contained at a ratio of 25 mass% or more and 80 mass% or less, the dicarboxylic acid constituting the dicarboxylic acid compound (B) is contained at a ratio of 0.01 mass% or more and 1 mass% or less, the nonionic surfactant (C) is contained at a ratio of 20 mass% or more and 90 mass% or less, the ionic surfactant (D) is contained at a ratio of 1 mass% or more and 10 mass% or less.

2. The synthetic fiber treatment agent according to claim 1, wherein The dicarboxylic acid compound (B) has 4 or more and 6 or less carbon atoms.

3. The synthetic fiber treatment agent according to claim 1, wherein The per-ester compound (Al) is contained at a ratio of 25 mass% or more and 70 mass% or less with respect to the total mass of the treatment agent for synthetic fibers.

4. A synthetic fiber, characterized by, synthetic fibers to which the treatment agent for synthetic fibers described in any one of claims 1 to 3 is attached.

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