Treatment agent for synthetic fibers, and synthetic fibers

Abstract

To improve yarn-converging characteristics of synthetic fibers.SOLUTION: A treatment agent for synthetic fibers contains an amine derivative (A) and a smoothing agent (B). The amine derivative (A) is a compound obtained by adding alkylene oxides having a carbon number of 2-4 at a proportion of 1-30 mol with respect to a total of 1 mol of an amine compound (A1) that has a hydrocarbon group having a carbon number of 8-20 and an amine compound (A2) that has a hydrocarbon group having a carbon number of 8-20, whose carbon number is different from that of the hydrocarbon group of the amine compound (A1).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a treatment agent for synthetic fibers and to synthetic fibers. [Background technology]

[0002] For example, synthetic fibers are produced by carrying out a spinning process in which acrylic resin or the like is spun into fibers. In order to improve the bundleability of the fibers that have been subjected to the spinning process (hereinafter also referred to as spun bundleability), a synthetic fiber treating agent may be used in the spinning process.

[0003] Patent Document 1 discloses a treatment agent for synthetic fibers that contains a nonionic surfactant and a smoothing agent. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-99964 A Summary of the Invention [Problem to be solved by the invention]

[0005] By the way, if the spinning bundle property is improved, it is possible to suppress winding around rollers in the synthetic fiber manufacturing process, and therefore it is possible to efficiently manufacture synthetic fibers. Furthermore, it can also contribute to improving the quality of synthetic fibers. Therefore, there is a demand for synthetic fiber treatment agents with further improved spinning bundle property. [Means for solving the problem]

[0006] The synthetic fiber treatment agent for solving the above problems contains the following amine derivative (A) and smoothing agent (B): The smoothing agent (B) contains an amino-modified silicone, and when the total content of the amine derivative (A) and the smoothing agent (B) is taken as 100 mass%, the amine derivative (A) is contained in an amount of 3 mass% or more and 50 mass% or less, and the smoothing agent (B) is contained in an amount of 50 mass% or more and 97 mass% or less. The gist of this is to

[0007] Amine derivative (A): A compound obtained by adding alkylene oxide having from 2 to 4 carbon atoms in a total amount of from 1 mole to 30 moles per mole of an amine compound (A1) having a hydrocarbon group having from 8 to 20 carbon atoms and an amine compound (A2) having a hydrocarbon group having from 8 to 20 carbon atoms and having a different carbon number from that of the hydrocarbon group of the amine compound (A1).

[0008] In the above-mentioned synthetic fiber treatment agent, the alkylene oxide preferably contains ethylene oxide. 。

[0009] It is preferable that the above-mentioned synthetic fiber treating agent further contains the following (poly)oxyalkylene derivative (C). (Poly)oxyalkylene derivative (C): A compound in which an alkylene oxide having 2 to 4 carbon atoms is added in a total ratio of 1 to 30 moles to 1 mole of a monohydric aliphatic alcohol having a hydroxyl group at the β-position of an alkyl chain having 4 or more carbon atoms.

[0010] With regard to the above-mentioned synthetic fiber treating agent, when the total content of the amine derivative (A), the smoothing agent (B), and the (poly)oxyalkylene derivative (C) is taken as 100 mass%, it is preferable that the agent contains the amine derivative (A) in an amount of 3 mass% or more and 40 mass% or less, the smoothing agent (B) in an amount of 20 mass% or more and 94 mass% or less, and the (poly)oxyalkylene derivative (C) in an amount of 3 mass% or more and 50 mass% or less.

[0011] In the above-mentioned synthetic fiber treating agent, the synthetic fiber is preferably a carbon fiber precursor. The synthetic fibers for solving the above problems have the above-mentioned synthetic fiber treating agent adhered thereto. Effect of the Invention

[0012] According to the present invention, it is possible to improve the spinning bundle property of synthetic fibers. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] (First embodiment) DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of a treatment agent for synthetic fibers (hereinafter also simply referred to as a treatment agent) according to the present invention will be described.

[0014] The treatment agent contains the following amine derivative (A) and smoothing agent (B). Amine derivative (A): A compound obtained by adding alkylene oxide having 2 to 4 carbon atoms in a total amount of 1 mole to 30 moles of an amine compound (A1) having a hydrocarbon group having 8 to 20 carbon atoms and an amine compound (A2) having a hydrocarbon group having 8 to 20 carbon atoms but a different carbon number from that of the hydrocarbon group of the amine compound (A1).

[0015] By containing the above-mentioned amine derivative (A) and smoothing agent (B) in the treatment agent, the spinning sizing property of the synthetic fibers can be improved. The hydrocarbon group having 8 to 20 carbon atoms in the amine compound (A1) is not particularly limited, and may be a straight-chain hydrocarbon group or a branched-chain hydrocarbon group, and may be a saturated or unsaturated hydrocarbon group.

[0016] Specific examples of the straight-chain hydrocarbon group include an octyl group, a nonyl group, a decyl group, a undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, an octadecyl group, and an icosyl group.

[0017] Specific examples of branched saturated hydrocarbon groups include isooctyl, isononyl, isodecyl, isoundecyl, isododecyl, isotridecyl, isotetradecyl, isopentadecyl, isohexadecyl, isoheptadecyl, isooctadecyl, and isoicosyl groups.

[0018] The unsaturated hydrocarbon group may be an alkenyl group having one double bond as an unsaturated carbon bond, or an alkadienyl group or an alkatrienyl group having two or more double bonds. The unsaturated carbon group may be an alkynyl group having one triple bond as an unsaturated carbon bond, or an alkadiynyl group having two or more triple bonds. Specific examples of linear unsaturated hydrocarbon groups having one double bond in the hydrocarbon group include, for example, an octenyl group, a nonenyl group, a decenyl group, an undecenyl group, a dodecenyl group, a tridecenyl group, a tetradecenyl group, a pentadecenyl group, a hexadecenyl group, a heptadecenyl group, an octadecenyl group, and an icosenyl group.

[0019] Specific examples of unsaturated hydrocarbon groups having a branched chain and one double bond in the hydrocarbon group include isooctenyl, isononenyl, isodecenyl, isoundecenyl, isododecenyl, isotridecenyl, isotetradecenyl, isopentadecenyl, isohexadecenyl, isoheptadecenyl, isooctadecenyl, and isoicosenyl groups.

[0020] The amine compound (A1) may be any one of a primary amine, a secondary amine, and a tertiary amine, and among these, a primary amine is preferable. The amine compound (A2) has a hydrocarbon group having a carbon number of 8 to 20, which is different from the carbon number of the hydrocarbon group of the amine compound (A1). Except for the carbon number of the hydrocarbon group being different, the same compounds as those exemplified as the amine compound (A1) can be used.

[0021] The amine compound (A2) is not limited to one type, and multiple types of amine compounds (A2) may be used. That is, multiple types of amine compounds (A2) having a hydrocarbon group with a carbon number of 8 to 20 different from that of the hydrocarbon group of the amine compound (A1) may be used. These multiple types of amine compounds (A2) preferably have different carbon numbers in the hydrocarbon groups. The multiple types of amine compounds (A2) may have the same carbon number in the hydrocarbon groups but different chemical formulas.

[0022] It is preferable that two or more kinds of the amine compound (A2) are used, more preferably three or more kinds, and further preferably five or more kinds are used. The mixing ratio of the amine compound (A1) and the amine compound (A2) is not particularly limited. For example, the mass ratio of the amine compound (A1) / the amine compound (A2) is preferably 1 / 99 or more and 99 / 1 or less, and more preferably 5 / 95 or more and 95 / 5 or less.

[0023] Examples of the alkylene oxide having 2 to 4 carbon atoms include ethylene oxide, propylene oxide, and butylene oxide. Among these, those containing ethylene oxide are preferred.

[0024] The polymerization sequence of the alkylene oxide is not particularly limited, and may be a random adduct or a block adduct. The alkylene oxides having 2 to 4 carbon atoms may be used alone or in combination of two or more.

[0025] The above-mentioned smoothing agent (B) is not particularly limited, and a known smoothing agent used in a treatment agent can be used. Examples of known smoothing agents include silicone oil, mineral oil, polyolefin, ester compounds, etc. These smoothing agents may be used alone or in combination of two or more. Among these, it is preferable that the smoothing agent (B) contains silicone oil.

[0026] Examples of silicone oils include dimethyl silicone, phenyl-modified silicone, amino-modified silicone, amide-modified silicone, polyether-modified silicone, aminopolyether-modified silicone, alkyl-modified silicone, alkylaralkyl-modified silicone, alkylpolyether-modified silicone, ester-modified silicone, epoxy-modified silicone, carbinol-modified silicone, mercapto-modified silicone, etc. Among these, those containing amino-modified silicone are preferred.

[0027] By including an amino-modified silicone in the lubricant (B), the synthetic fiber is made flame-resistant, and the strength of the carbon fiber produced by carbonization can be further improved.

[0028] Specific examples of the smoothing agent (B) include those having a kinetic viscosity of 650 mm at 25° C. 2 / s and amino equivalent of 1800g / mol. 2 / s and amino equivalent of 5000g / mol. 2 / s and amino equivalent of 1200g / mol. 2 / s and amino equivalent of 1000g / mol. 2 Examples of the silicone rubber include dimethyl silicone (Si / s) and didodecyl ester of an adduct of 2 moles of ethylene oxide with bisphenol A.

[0029] The above silicone oils may be used alone or in combination of two or more. The kinetic viscosity of the lubricating agent (B) can be measured by a known method at 25° C. using a Cannon-Fenske viscometer.

[0030] There is no limitation on the content ratio of the amine derivative (A) and the smoothing agent (B). When the total content ratio of the amine derivative (A) and the smoothing agent (B) is 100 parts by mass, it is preferable that the amine derivative (A) is contained in a ratio of 3 mass% to 50 mass% and the smoothing agent (B) is contained in a ratio of 50 mass% to 97 mass%.

[0031] The treatment agent preferably further contains the following (poly)oxyalkylene derivative (C). (Poly)oxyalkylene derivative (C): A compound in which an alkylene oxide having 2 to 4 carbon atoms is added in a total ratio of 1 to 30 moles to 1 mole of a monohydric aliphatic alcohol having a hydroxyl group at the β-position of an alkyl chain having 4 or more carbon atoms.

[0032] By containing the (poly)oxyalkylene derivative (C), the spinning bundle property can be further improved. The monohydric aliphatic alcohol is not particularly limited, and may be a straight-chain aliphatic alcohol or a branched-chain aliphatic alcohol, and may be a saturated aliphatic alcohol or an unsaturated aliphatic alcohol.

[0033] The alcohol may be any of primary, secondary and tertiary alcohols, with primary alcohols being preferred. The number of carbon atoms in the alkyl chain of the monohydric aliphatic alcohol is preferably 10 or more, and more preferably 12 or more. The number of carbon atoms in the alkyl chain of the monohydric aliphatic alcohol is preferably 18 or less, and more preferably 16 or less.

[0034] Specific examples of the alkyl chain include those similar to the hydrocarbon group of the amine compound (A1) used in the amine derivative (A). Examples of the alkylene oxide having 2 to 4 carbon atoms include the same alkylene oxides as those used in the amine derivative (A).

[0035] Specific examples of the (poly)oxyalkylene derivative (C) include a compound in which 5 moles of ethylene oxide are added to 1 mole of 2-dodecanol, and a compound in which 9 moles of ethylene oxide are added to 1 mole of 2-tetradecanol.

[0036] The (poly)oxyalkylene derivative (C) may be used alone or in combination of two or more kinds. There is no limitation on the content ratio of the amine derivative (A), the smoothing agent (B), and the (poly)oxyalkylene derivative (C). When the total content ratio of the amine derivative (A), the smoothing agent (B), and the (poly)oxyalkylene derivative (C) is 100 parts by mass, it is preferable that the amine derivative (A) is contained in an amount of 3% by mass to 40% by mass, the smoothing agent (B) is contained in an amount of 20% by mass to 94% by mass, and the (poly)oxyalkylene derivative (C) is contained in an amount of 3% by mass to 50% by mass.

[0037] Second embodiment 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. Specific examples of synthetic fibers are not particularly limited, and include, for example, (1) polyester-based fibers such as polyethylene terephthalate, polypropylene terephthalate, and polylactic acid ester, (2) polyamide-based fibers such as nylon 6 and nylon 66, (3) polyacrylic-based fibers such as polyacrylic and modacrylic, (4) polyolefin-based fibers such as polyethylene and polypropylene, (5) cellulose-based fibers, and (6) lignin-based fibers.

[0038] The synthetic fibers are preferably synthetic fibers made of resin that become carbon fibers through a carbonization process described below. In other words, the synthetic fibers are preferably carbon fiber precursors.

[0039] The resin constituting the synthetic fibers is not particularly limited, but examples thereof include acrylic resin, polyethylene resin, phenolic resin, cellulose resin, lignin resin, pitch, and the like.

[0040] There is no particular restriction on the proportion of the treatment agent of the first embodiment that is applied to the synthetic fibers, but it is preferable to apply the treatment agent (not including the solvent) in an amount of 0.1% by mass or more and 2% by mass or less relative to the synthetic fibers, and it is more preferable to apply the treatment agent in an amount of 0.3% by mass or more and 1.2% by mass or less.

[0041] The treatment agent of the first embodiment may be applied to synthetic fibers in the form of, for example, an organic solvent solution, an aqueous liquid, or the like. The treatment agent can be applied to synthetic fibers by a known method, such as a dipping method, a spray method, a roller method, or a guide oiling method using a metering pump, using, for example, an aqueous liquid containing the treatment agent of the first embodiment and water, or a further diluted aqueous solution.

[0042] A method for producing carbon fibers using the synthetic fibers of this embodiment will be described. The method for producing carbon fibers preferably includes the following steps 1 to 3. Step 1: A spinning step in which synthetic fibers that will become carbon fiber precursors are spun and the treatment agent of the first embodiment is applied to the synthetic fibers.

[0043] Step 2: A flame-retardant treatment step of converting the carbon fiber precursor obtained in step 1 into a flame-retardant fiber in an oxidizing atmosphere at 200° C. or higher and 300° C. or lower, preferably 230° C. or higher and 270° C. or lower. Step 3: A carbonization treatment step in which the flame-retardant fiber obtained in step 2 is further carbonized in an inert atmosphere at a temperature of 300° C. or higher and 2000° C. or lower, preferably 300° C. or higher and 1300° C. or lower.

[0044] The above steps 2 and 3 constitute a firing step. The spinning process preferably further includes a wet spinning process in which a resin is dissolved in a solvent and spun, a drying and densifying process in which the wet spun synthetic fibers are dried and densified, and a stretching process in which the dried and densified synthetic fibers are stretched. The treatment agent of the first embodiment is preferably applied between the wet spinning process and the drying and densifying process.

[0045] The temperature of the drying and densifying step is not particularly limited, but it is preferable to heat the synthetic fibers that have been subjected to the wet spinning step to, for example, 70° C. or more and 200° C. or less. The timing of attaching the treatment agent to the synthetic fibers is not particularly limited, but it is preferable to attach the treatment agent between the wet spinning step and the drying and densifying step.

[0046] The oxidizing atmosphere in the flame-proofing treatment step is not particularly limited, and for example, an air atmosphere can be used. The inert atmosphere in the carbonization treatment step is not particularly limited, and for example, a nitrogen atmosphere, an argon atmosphere, a vacuum atmosphere, or the like can be adopted.

[0047] The treatment agent and synthetic fibers of this embodiment can provide the following actions and effects. (1) The treatment agent of the present embodiment contains the above-mentioned amine derivative (A) and smoothing agent (B). Therefore, it is possible to improve the spinning and bundling properties of synthetic fibers. It is also possible to improve the flame-retardant bundling properties of synthetic fibers and the strength of carbon fibers produced by carbonizing synthetic fibers.

[0048] (2) The smoothing agent (B) contains at least one selected from amino-modified silicones and polyether-modified silicones, which can improve at least one of the flame-retardant bundling properties of the synthetic fibers and the strength of the carbon fibers produced by carbonizing the synthetic fibers.

[0049] (3) The smoothing agent (B) contains amino-modified silicone, which can further improve the strength of the carbon fiber. (4) It contains the above-mentioned (poly)oxyalkylene derivative (C), which can further improve the spinning bundle property.

[0050] The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other to the extent that no technical contradiction occurs. In this embodiment, the treatment agent is applied to the synthetic fibers between the wet spinning process and the drying and densifying process, but this is not limited to the above. The treatment agent may be applied to the synthetic fibers between the drying and densifying process and the drawing process, or between the drawing process and the flame-resistant treatment process.

[0051] In this embodiment, the synthetic fibers may be fibers that are not subjected to a sintering process, that is, the synthetic fibers are not limited to carbon fiber precursors. The treatment agent of this embodiment may further contain components that are typically used in treatment agents, such as stabilizers for maintaining the quality of the treatment agent, antistatic agents, antistatic agents, binders, antioxidants, UV absorbers, and defoamers (silicone-based compounds), within the scope that does not impair the effects of the present invention. EXAMPLES

[0052] In the following, examples will be given to more specifically describe the configuration and effects of the present invention, but the present invention is not limited to these examples. In the following examples and comparative examples, parts means parts by mass, and % means % by mass.

[0053] Test Category 1 (Preparation of treatment agent for carbon fiber precursors) Example 1 The components shown in Table 1 were added to a beaker in a blending ratio of 15 parts of amine derivative (A-1), 50 parts of smoothing agent (B-1), and 35 parts of (poly)oxyalkylene derivative (C-1). These were thoroughly mixed by stirring. While continuing to stir, ion-exchanged water was gradually added so that the solid content concentration was 25%, thereby preparing a 25% aqueous solution of the synthetic fiber treatment agent of Example 1.

[0054] (Example 2 18,20~22, Reference example 19,23, 24 and Comparative Examples 1 to 3) Example 2 18,20~22, Reference example 19,23, Each of the carbon fiber precursor treating agents No. 24 and Comparative Examples 1 to 3 was prepared in the same manner as in Example 1 using the components shown in Table 1.

[0055] The type and content of the amine derivative (A), the type and content of the smoothing agent (B), and the type and content of the (poly)oxyalkylene derivative (C) in each example of the treatment agent are as shown in the "Amine derivative (A)" column, the "Smoothing agent (B)" column, and the "(poly)oxyalkylene derivative (C)" column in Table 1, respectively.

[0056] [Table 1]

[0057] Details of the amine derivative (A), the smoothing agent (B), and the (poly)oxyalkylene derivative (C) in Table 1 are as follows. (Amine derivatives (A)) The types and blending ratios of the amine compound (A1) and the amine compound (A2), and the type and number of moles of the alkylene oxide having 2 to 4 carbon atoms in the amine derivative (A) in Table 1 are shown in the columns "Type and blending ratio (parts by mass) of amine compound" and "Type and number of moles of alkylene oxide added", respectively.

[0058] In Table 2, "C8" means an amine compound with 8 carbon atoms in the hydrocarbon group, "C16:1" means an amine compound with 16 carbon atoms in the hydrocarbon group and one unsaturated bond, and so on.

[0059] The compounds with an asterisk (*) on the right side of the numbers indicate amine compound (A1), and all others indicate amine compound (A2). 2 Here, the amine compound contained in the amine derivative (A-9) is referred to as amine compound (A1), and the amine compound contained in the amine derivative (A-10) is referred to as amine compound (A2). EO stands for ethylene oxide, and PO stands for propylene oxide.

[0060] The amine derivatives (A-1), (A-3) to (A-8) were prepared by adding EO to a mixed solution of 1 mole of the amine compound (A1) and the amine compound (A2). Amine derivative (A-2) was prepared by block-adding EO and PO in that order to a mixture of 1 mole of amine compound (A1) and amine compound (A2). All of the amine derivatives (A-1) to (A-10) used primary amines with linear hydrocarbon groups.

[0061] The method for preparing the amine derivatives (A-1) to (A-8) is not limited to the method of adding an alkylene oxide to a mixed solution of amine compounds. The amine derivatives (A-1) to (A-8) may be prepared by adding an alkylene oxide to each amine compound individually and then mixing them.

[0062] [Table 2]

[0063] a-1: A compound in which 15 moles of ethylene oxide and 10 moles of propylene oxide are added to 1 mole of distyrenated phenol a-2: A compound in which 15 moles of ethylene oxide and 10 moles of propylene oxide are added to 1 mole of tristyrenated phenol (Smoothing agent (B)) B-1: Kinematic viscosity at 25°C is 650mm 2 / s and amino equivalent of 1800g / mol. B-2: Kinematic viscosity at 25°C is 90mm 2 / s and amino equivalent of 5000g / mol. B-3: Kinematic viscosity at 25°C is 4500mm 2 / s and amino equivalent of 1200g / mol. B-4: Kinematic viscosity at 25°C is 8000mm 2 / s and amino equivalent of 1000g / mol. B-5: Kinematic viscosity at 25°C is 350mm 2 / s dimethyl silicone B-6: Didodecyl ester of 2 moles of ethylene oxide adduct of bisphenol A ((Poly)oxyalkylene Derivative (C)) C-1: A compound in which 5 moles of ethylene oxide are added to 1 mole of 2-dodecanol C-2: A compound in which 9 moles of ethylene oxide are added to 1 mole of 2-tetradecanol Test Category 2 (Manufacturing of synthetic and carbon fibers) The aqueous solution of the synthetic fiber treatment agent prepared in Test Section 1 was used to manufacture synthetic fibers and carbon fibers.

[0064] First, in step 1, an acrylic resin was wet-spun. Specifically, a copolymer consisting of 95% by mass of acrylonitrile, 3.5% by mass of methyl acrylate, and 1.5% by mass of methacrylic acid and having an intrinsic viscosity of 1.80 was dissolved in dimethylacetamide (DMAC) to prepare a spinning dope having a polymer concentration of 21.0% by mass and a viscosity of 500 poise at 60° C. The spinning dope was discharged from a spinneret having a hole diameter (inner diameter) of 0.075 mm and 12,000 holes into a coagulation bath of a 70% by mass aqueous solution of DMAC kept at a spinning bath temperature of 35° C., at a draft ratio of 0.8.

[0065] The coagulated yarn was stretched 5 times in a water washing tank while removing the solvent, to produce a water-swollen acrylic fiber strand (raw fiber). The synthetic fiber treatment agent prepared in Test Section 1 was added to this acrylic fiber strand so that the solid content adhesion amount was 1 mass% (not including the solvent). The synthetic fiber treatment agent was added by immersion using a 4% ion-exchange aqueous solution of the synthetic fiber treatment agent. The acrylic fiber strand was then dried and densified with heated rollers at 130°C, and further stretched 1.7 times between heated rollers at 170°C, and then wound onto a bobbin using a winding device.

[0066] Next, in step 2, a yarn was unwound from the wound carbon fiber precursor and subjected to a flame-retardant treatment in an air atmosphere for 1 hour in a flame-retardant furnace having a temperature gradient of 230°C or higher and 270°C or lower, and then the yarn was wound onto a yarn tube to obtain a flame-retardant yarn (flame-retardant fiber).

[0067] Next, in step 3, the yarn was unwound from the wound flame-retardant yarn and baked in a carbonization furnace having a temperature gradient of 300°C or more and 1300°C or less under a nitrogen atmosphere to convert it into carbon fiber, and then the carbon fiber was obtained by winding it up around a yarn tube.

[0068] Test category 3 (evaluation) Example 1 18,20~22, Reference example 19,23, The spinning bundle property, flame retardant bundle property, and carbon fiber strength were evaluated for the treatment agents of No. 24 and Comparative Examples 1 to 3. The procedures for each test are shown below. The test results are shown in the "Spinning bundle property", "Flame retardant bundle property", and "Strength" columns of Table 1.

[0069] (Spinning bundle property) The acrylic fiber strands that had been oiled with the synthetic fiber treatment agent in step 1 of test section 2 were visually observed for bundling state as they passed through a heated roller at 130°C, and were evaluated according to the following criteria.

[0070] Evaluation criteria for spinning bundle property ◎ (Good): The fibers are bundled together to form a relatively narrow yarn width, there is no wrapping around the heating roller, and there are no problems with operability. Good (Acceptable): The yarn is slightly loose and the yarn width is slightly wider, but it is not wrapped around the heating roller and there is no problem with operability. × (Not acceptable): The yarn is loose and wide, and frequently breaks due to wrapping around the heating roller, affecting operability. (Flame resistant focusing) The state of the bundle of flame-retardant fibers that had been flame-retardant treated in step 2 of test section 2 before being wound onto a bobbin was visually observed and evaluated according to the following criteria.

[0071] Evaluation criteria for flame retardant convergence ○ (Acceptable): When the fibers are bundled but there is no space in the fiber bundle. × (Not acceptable): When the fibers are not bundled and there are spaces in the fiber bundle, making the tow width wider. (strength) The strength of the carbon fiber obtained in step 3 of test section 2 was measured in accordance with JIS R 7606. Evaluation was based on the following criteria.

[0072] Strength evaluation criteria ◎ (Good): Strength is 4.0GPa or more, but less than 4.5GPa 〇(Acceptable): Strength is 3.5GPa or more, but less than 4.0GPa × (Not acceptable): Strength is less than 3.5 GPa From the results in Table 1, it can be seen that the present invention can improve the spinning sizing property of synthetic fibers, and can also improve the flame-resistant sizing property and the strength of carbon fibers.

Claims

1. The composition contains the following amine derivative (A) and smoothing agent (B), The smoothing agent (B) contains an amino-modified silicone, The synthetic fiber treatment agent contains the amine derivative (A) in an amount of 3 mass% or more and 50 mass% or less, and the smoothing agent (B) in an amount of 50 mass% or more and 97 mass% or less, when the total content of the amine derivative (A) and the smoothing agent (B) is 100 mass%. Amine derivative (A): A compound obtained by adding an alkylene oxide having from 2 to 4 carbon atoms in a total ratio of from 1 mol to 30 mol per 1 mol of an amine compound (A1) having a hydrocarbon group having from 8 to 20 carbon atoms and an amine compound (A2) having a hydrocarbon group having from 8 to 20 carbon atoms and having a different carbon number from that of the hydrocarbon group of the amine compound (A1).

2. 2. The synthetic fiber treating agent according to claim 1, wherein the alkylene oxide comprises ethylene oxide.

3. 3. The synthetic fiber treating agent according to claim 1, further comprising the following (poly)oxyalkylene derivative (C): (Poly)oxyalkylene derivative (C): A compound in which an alkylene oxide having from 2 to 4 carbon atoms is added in a total amount of from 1 to 30 moles to 1 mole of a monohydric aliphatic alcohol having a hydroxy group at the β-position of an alkyl chain having 4 or more carbon atoms.

4. 4. The synthetic fiber treatment agent according to claim 3, wherein the synthetic fiber treatment agent contains the amine derivative (A) in an amount of 3% by mass or more and 40% by mass or less, the smoothing agent (B) in an amount of 20% by mass or more and 94% by mass or less, and the (poly)oxyalkylene derivative (C) in an amount of 3% by mass or more and 50% by mass or less, assuming that the total content of the amine derivative (A), the smoothing agent (B), and the (poly)oxyalkylene derivative (C) is 100% by mass.

5. The synthetic fiber treating agent according to any one of claims 1 to 4, wherein the synthetic fiber is a carbon fiber precursor.

6. A synthetic fiber having the synthetic fiber treating agent according to any one of claims 1 to 5 adhered thereto.

Images