Treatment agents for synthetic fibers and synthetic fibers

Abstract

The objective of this invention is to improve the spinning bundle properties of synthetic fibers. The synthetic fiber treatment agent contains the following amine derivative (A) and a smoothing agent (B). The amine derivative (A) is a compound formed by adding an epoxide with 2 to 4 carbon atoms to a total of 1 mole of an amine compound (A1) having a hydrocarbon group with 8 to 20 carbon atoms, and an amine compound (A2) having a hydrocarbon group with 8 to 20 carbon atoms, which has a different number of carbon atoms than the hydrocarbon group of the aforementioned amine compound (A1), in a ratio of 1 to 30 moles.

Description

Technical Field

[0001] This invention relates to treatment agents for synthetic fibers and synthetic fibers themselves. Background Technology

[0002] Synthetic fibers are manufactured, for example, by a spinning process in which acrylic resins or the like are spun.

[0003] In order to improve the bundle properties of fibers that have undergone the spinning process (hereinafter also referred to as spinning bundle properties), synthetic fiber treatment agents are sometimes used in the spinning process.

[0004] Patent document 1 discloses a treatment agent for synthetic fibers, which contains a nonionic surfactant and a smoothing agent.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2019-99964 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] If the spinning bundle property is improved, entanglement on the rollers can be suppressed during the synthetic fiber manufacturing process, thus enabling efficient production of synthetic fibers. Furthermore, it can help improve the quality of synthetic fibers. Therefore, for synthetic fiber treatment agents, there is a requirement for further improvement in the spinning bundle property.

[0010] Methods for solving problems

[0011] The key point of the synthetic fiber treatment agent used to solve the above problems is that it contains the following amine derivative (A) and smoothing agent (B).

[0012] Amine derivative (A): A compound formed by adding an epoxide having 2 or more and 4 or fewer carbon atoms to a total of 1 mole of an amine compound (A1) having a hydrocarbon group having a carbon ...

[0013] In the above-mentioned synthetic fiber treatment agent, the epoxide preferably contains ethylene oxide.

[0014] In the above-mentioned synthetic fiber treatment agent, the smoothing agent (B) preferably contains amino-modified silicone.

[0015] In the above-mentioned synthetic fiber treatment agent, when the total content of the above-mentioned amine derivative (A) and the above-mentioned smoothing agent (B) is set to 100% by mass, it is preferable that the above-mentioned amine derivative (A) is contained in a proportion of 3% or more and 50% or less by mass, and the above-mentioned smoothing agent (B) is contained in a proportion of 50% or more and 97% or less by mass.

[0016] The above-mentioned synthetic fiber treatment agent preferably further contains the following (poly)oxyalkylene derivative (C).

[0017] (Poly)oxyalkylene derivative (C): A compound formed by adding an epoxide having 2 or more and 4 or fewer carbon atoms to 1 mole of a monoaliphatic alcohol having a hydroxyl group at the β position of an alkyl chain having 4 or more carbon atoms in a total ratio of 1 mole or more and 30 moles or less.

[0018] In the above-mentioned synthetic fiber treatment agent, when the total content of the above-mentioned amine derivative (A), the above-mentioned smoothing agent (B), and the above-mentioned (poly)oxyalkylene derivative (C) is set to 100% by mass, it is preferable that the above-mentioned amine derivative (A) is contained in a proportion of 3% or more and 40% or less by mass, the above-mentioned smoothing agent (B) is contained in a proportion of 20% or more and 94% or less by mass, and the above-mentioned (poly)oxyalkylene derivative (C) is contained in a proportion of 3% or more and 50% or less by mass.

[0019] In the above-mentioned synthetic fiber treatment agent, the synthetic fiber is preferably a carbon fiber precursor.

[0020] The key point of the synthetic fiber used to solve the above-mentioned problem is that it is coated with the aforementioned synthetic fiber treatment agent.

[0021] The effects of the invention

[0022] According to the present invention, the spinning bundle properties of synthetic fibers can be improved. Detailed Implementation

[0023] (First Embodiment)

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

[0025] The treatment agent contains the following amine derivative (A) and a smoothing agent (B).

[0026] Amine derivative (A): A compound formed by adding an epoxide having 2 or more and 4 or fewer carbon atoms to a total of 1 mole of an amine compound (A1) having a hydrocarbon group having a different number of carbon atoms than the hydrocarbon group of the amine compound (A1) and an amine compound (A2) having a hydrocarbon group having a different number of carbon atoms than the hydrocarbon group of the amine compound (A1).

[0027] By including the above-mentioned amine derivative (A) and smoothing agent (B) in the treatment agent, the spinning bundle properties of synthetic fibers can be improved.

[0028] There are no particular restrictions on the hydrocarbon group with 8 or more but less than 20 carbon atoms in the above-mentioned amine compound (A1). It can be a straight-chain hydrocarbon group or a branched hydrocarbon group. In addition, it can be a saturated hydrocarbon group or an unsaturated hydrocarbon group.

[0029] Specific examples of straight-chain hydrocarbon groups include octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecanyl, octadecyl, and eicosyl.

[0030] Specific examples of saturated hydrocarbon groups with branched chains include isooctyl, isononyl, isodecyl, isoundecyl, isoundecyl, isotridecyl, isotetradecyl, isopentadecanyl, isohexadecyl, isoheptadecyl, isooctadecyl, isoeicosyl, etc.

[0031] As an unsaturated hydrocarbon group, it can be an alkenyl group having one double bond as an unsaturated carbon bond, or a dienyl or trienyl group having two or more double bonds. Alternatively, it can be an alkynyl group having one triple bond as an unsaturated carbon bond, or a diynyl group having two or more triple bonds. Specific examples of straight-chain unsaturated hydrocarbon groups having one double bond include octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tridecenyl, tetradecenyl, pentadecenyl, hexadecenyl, heptadecanyl, octadecenyl, and eicosenecanyl.

[0032] Specific examples of unsaturated hydrocarbon groups having one double bond and being branched include isooctenyl, isononenyl, isodelenyl, isodecenyl, isoundecenyl, isodecenyl, isotridecenyl, isotetradecenyl, isopentadecanenyl, isopentadecanenyl, isohexadecenyl, isoheptadecenyl, isooctadecenyl, and isoeicosenecanenyl.

[0033] The amine compound (A1) mentioned above can be any of a primary amine, a secondary amine, or a tertiary amine. Among these, a primary amine is preferred.

[0034] The amine compound (A2) described above has a hydrocarbon group with 8 or more but less than 20 carbon atoms, which is different from the hydrocarbon group of the amine compound (A1). Compounds identical to those exemplified in the amine compound (A1) described above can be used, except for the difference in the number of carbon atoms in the hydrocarbon group.

[0035] The aforementioned amine compound (A2) is not limited to one type; multiple amine compounds (A2) may be used. That is, multiple amine compounds (A2) may be used that have a hydrocarbon group having 8 or more but less than 20 carbon atoms, which differs from the hydrocarbon group of the amine compound (A1). Preferably, these multiple amine compounds (A2) have hydrocarbon groups with different numbers of carbon atoms. Multiple amine compounds (A2) may also be compounds with the same number of carbon atoms in their hydrocarbon groups but different chemical formulas.

[0036] Two or more amine compounds (A2) are preferably used, more preferably three or more, and even more preferably five or more.

[0037] There are no particular restrictions on the mixing ratio of amine compound (A1) and amine compound (A2). For example, by mass ratio, it is preferred that the ratio of amine compound (A1) to amine compound (A2) is 1 / 99 or more and 99 / 1 or less, and more preferably that the ratio of amine compound (A1) to amine compound (A2) is 5 / 95 or more and 95 / 5 or less.

[0038] Examples of epoxides with 2 or more but less than 4 carbon atoms include ethylene oxide, propylene oxide, and butane oxide. Among these, ethylene oxide is preferred.

[0039] There are no particular restrictions on the polymerization arrangement of epoxides; they can be random adducts or block adducts.

[0040] The aforementioned epoxides with 2 or more but less than 4 carbon atoms can be used alone or in combination of two or more.

[0041] There are no particular limitations on the smoothing agent (B) mentioned above, and any known smoothing agent used in the treatment agent can be used. Examples of known smoothing agents include silicone oil, mineral oil, polyolefins, ester compounds, etc. These smoothing agents can be used alone or in combination of two or more. Among these, smoothing agent (B) preferably contains silicone oil.

[0042] Examples of silicone oils include dimethyl silicone, phenyl-modified silicone, amino-modified silicone, amide-modified silicone, polyether-modified silicone, amino-polyether-modified silicone, alkyl-modified silicone, alkyl-aralkyl-modified silicone, alkyl-polyether-modified silicone, ester-modified silicone, epoxy-modified silicone, methanol-modified silicone, and mercapto-modified silicone. Among these, amino-modified silicone is preferred.

[0043] By including amino-modified silicone in the smoothing agent (B), the strength of the carbon fiber can be further improved when the synthetic fiber is made fire-resistant and further carbonized.

[0044] As a specific example of a smoothing agent (B), one could cite an example with a kinematic viscosity of 650 mm at 25°C. 2 / s, amino-modified silicone with an amino equivalent of 1800 g / mol; kinematic viscosity at 25℃ is 90 mm. 2 / s, amino-modified silicone with an amino equivalent of 5000 g / mol; kinematic viscosity at 25℃ is 4500 mm. 2 / s, amino-modified silicone with an amino equivalent of 1200 g / mol; kinematic viscosity at 25℃ is 8000 mm. 2 / s, amino-modified silicone with an amino equivalent of 1000 g / mol; kinematic viscosity at 25℃ is 350 mm. 2 Dimethyl silicone; di(dodecyl) ester of 2 molar ethylene oxide adduct of bisphenol A, etc.

[0045] The aforementioned silicone oils can be used alone or in combination of two or more.

[0046] It should be noted that the kinematic viscosity of the smoothing agent (B) can be determined using a Cannon-Fensk viscometer at 25°C using a known method.

[0047] There is no limitation on the proportion of amine derivative (A) and smoothing agent (B) in the treatment agent. When the total proportion of amine derivative (A) and smoothing agent (B) in the treatment agent is set to 100 parts by mass, it is preferable that the amine derivative (A) is contained in a proportion of 3% by mass or more and 50% by mass or less, and the smoothing agent (B) is contained in a proportion of 50% by mass or more and 97% by mass or less.

[0048] The treatment agent preferably further contains the following (poly)oxyalkylene derivative (C).

[0049] (Poly)oxyalkylene derivatives (C) are compounds formed by adding an epoxide having 2 or more and 4 or fewer carbon atoms to 1 mole of a monoaliphatic alcohol having a hydroxyl group at the β-position of an alkyl chain having 4 or more carbon atoms in a total ratio of 1 mole or more and 30 moles or less.

[0050] By including the above-mentioned (poly)oxyalkylene derivative (C) in the treatment agent, the spinning bundling property can be further improved.

[0051] There are no particular restrictions on the aforementioned monohydric aliphatic alcohols; they can be straight-chain aliphatic alcohols or branched aliphatic alcohols. Furthermore, they can be saturated aliphatic alcohols or unsaturated aliphatic alcohols.

[0052] Alternatively, it can be any of primary, secondary, or tertiary alcohols. Among these, primary alcohols are preferred.

[0053] The alkyl chain of the aforementioned monoaliphatic alcohol preferably has 10 or more carbon atoms, more preferably 12 or more. Furthermore, the alkyl chain of the monoaliphatic alcohol preferably has 18 or fewer carbon atoms, more preferably 16 or fewer.

[0054] As a specific example of the alkyl chain described above, one can cite a group that is the same as the hydrocarbon group in the amine compound (A1) used in the amine derivative (A) described above.

[0055] As an epoxide with 2 or more but less than 4 carbon atoms, the same substance as the epoxide used in the amine derivative (A) can be cited.

[0056] Specific examples of the aforementioned (poly)oxyalkylene derivative (C) include compounds formed by adding 5 moles of ethylene oxide to 1 mole of 2-dodecanol, and compounds formed by adding 9 moles of ethylene oxide to 1 mole of 2-tetradecanol.

[0057] The above-mentioned (poly)oxyalkylene derivative (C) can be used alone or in combination of two or more.

[0058] There are no restrictions on the proportions of the amine derivative (A), the smoothing agent (B), and the (poly)oxyalkylene derivative (C) in the treatment agent. When the total proportion of the amine derivative (A), the smoothing agent (B), and the (poly)oxyalkylene derivative (C) in the treatment agent is set to 100 parts by mass, it is preferable that the amine derivative (A) is contained in a proportion of 3% to 40% by mass, the smoothing agent (B) is contained in a proportion of 20% to 94% by mass, and the (poly)oxyalkylene derivative (C) is contained in a proportion of 3% to 50% by mass.

[0059] (Second Implementation)

[0060] The second embodiment, which embodies the synthetic fiber of the present invention, will be described. The synthetic fiber of this embodiment is coated with the treatment agent of the first embodiment. There are no particular limitations on the specific examples of synthetic fibers, and examples include: (1) polyester fibers such as polyethylene terephthalate, polypropylene terephthalate, and polylactic acid ester; (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; (5) cellulose fibers; and (6) lignin fibers, etc.

[0061] As a synthetic fiber, it is preferably a synthetic fiber made from a resin that produces carbon fibers through a carbonization process described later. In other words, the synthetic fiber is preferably a carbon fiber precursor.

[0062] There are no particular limitations on the resins that make up synthetic fibers. Examples include acrylic resins, polyethylene resins, phenolic resins, cellulose resins, lignin resins, and asphalt.

[0063] There is no particular limitation on the proportion of the treatment agent of the first embodiment that is attached to the synthetic fiber. It is preferable to attach the treatment agent (without solvent) in such a way that it is 0.1% by mass or more and 2% by mass or less relative to the synthetic fiber, and more preferably in such a way that it is 0.3% by mass or more and 1.2% by mass or less.

[0064] Examples of treatment agents that can be used to attach the treatment agent of the first embodiment to synthetic fibers include organic solvent solutions and aqueous solutions.

[0065] As a method for attaching the treatment agent to synthetic fibers, for example, the following method can be applied: using the treatment agent of the first embodiment, and an aqueous liquid containing water or an aqueous solution further diluted, the agent is attached by known methods, such as impregnation, spraying, rolling, or oiling with a yarn guide using a metering pump.

[0066] The method for manufacturing carbon fibers using the synthetic fibers of this embodiment will be described.

[0067] The preferred method for manufacturing carbon fiber involves the following steps 1 to 3.

[0068] Step 1: A spinning process in which synthetic fibers, which are precursors to carbon fibers, are spun and the treatment agent of the first embodiment is attached.

[0069] Step 2: A refractory treatment process in which the carbon fiber precursor obtained in Step 1 is converted into refractory fibers in an oxidizing atmosphere of 200°C or higher and 300°C or lower, preferably 230°C or higher and 270°C.

[0070] Step 3: A carbonization process in which the refractory fibers obtained in Step 2 are further carbonized in an inert atmosphere at a temperature of 300°C or higher and 2000°C or lower, preferably at a temperature of 300°C or higher and 1300°C or lower.

[0071] It should be noted that the firing process is constituted by the above-mentioned steps 2 and 3.

[0072] The spinning process preferably further includes a wet spinning process in which the resin is dissolved in a solvent and spun, a drying and densification process in which the synthetic fiber obtained by wet spinning is dried to make it dense, and a stretching process in which the dried and densified synthetic fiber is stretched. Preferably, the treatment agent of the first embodiment is applied between the wet spinning process and the drying and densification process.

[0073] The temperature of the drying and densification process is not particularly limited, but it is preferable to heat the synthetic fibers that have undergone the wet spinning process at, for example, 70°C or higher and 200°C or lower. The timing of applying the treatment agent to the synthetic fibers is not particularly limited, but it is preferably between the wet spinning process and the drying and densification process.

[0074] There are no particular restrictions on the oxidizing atmosphere in the refractory treatment process; for example, an air atmosphere can be used.

[0075] There are no particular limitations on the inert atmosphere used in the carbonization process; for example, nitrogen atmosphere, argon atmosphere, vacuum atmosphere, etc., can be used.

[0076] The following effects and benefits can be obtained from the treatment agent and synthetic fiber according to this embodiment.

[0077] (1) The processing agent in this embodiment contains the above-mentioned amine derivative (A) and a smoothing agent (B). Therefore, the spinning bundle properties of synthetic fibers can be improved. In addition, the fire-resistant bundle properties of synthetic fibers and the strength of carbon fibers produced by carbonizing synthetic fibers can be improved.

[0078] (2) The smoothing agent (B) comprises at least one selected from amino-modified silicone and polyether-modified silicone. Therefore, it is possible to further improve at least one of the following: the fire-resistant bundle properties of synthetic fibers and the strength of carbon fibers when the synthetic fibers are carbonized to produce carbon fibers.

[0079] (3) The smoothing agent (B) contains amino-modified silicone. Therefore, it can further improve the strength of carbon fibers.

[0080] (4) By including the above-mentioned (poly)oxyalkylene derivative (C) in the treatment agent, the spinning bundle property can be further improved.

[0081] The above-described embodiments can be implemented with the following modifications. The above-described embodiments and the following modifications can be combined with each other to implement them without technical inconsistencies.

[0082] In this embodiment, the treatment agent is applied to the synthetic fiber between the wet spinning process and the drying and densification process, but this method is not limited to this. The treatment agent can be applied to the synthetic fiber between the drying and densification process and the stretching process, or between the stretching process and the refractory treatment process.

[0083] In this embodiment, the synthetic fiber can be a fiber that has not undergone a firing process. That is, the synthetic fiber is not limited to carbon fiber precursors.

[0084] • In the treatment agent of this embodiment, without impairing the effects of the present invention, stabilizers, charge control agents, antistatic agents, thickeners, antioxidants, ultraviolet absorbers, defoamers (silicone compounds) and other components commonly used in treatment agents may be further mixed in to maintain the quality of the treatment agent.

[0085] Example

[0086] In the following description, embodiments are given to illustrate the structure and effects of the present invention in more detail, but the present invention is not limited to these embodiments. It should be noted that in the following descriptions of embodiments and comparative examples, parts refer to parts by mass, and % refers to percentages by mass.

[0087] Experimental Group 1 (Preparation of Treatment Agent for Carbon Fiber Precursor)

[0088] (Example 1)

[0089] Using the components shown in Table 1, add them to a beaker in the following mixing ratio: 15 parts of amine derivative (A-1), 50 parts of smoothing agent (B-1), and 35 parts of (poly)oxyalkylene derivative (C-1). Stir them thoroughly. While continuing to stir, slowly add ion-exchanged water to achieve a solids concentration of 25%, thereby preparing a 25% aqueous solution of the synthetic fiber treatment agent of Example 1.

[0090] (Examples 2-24 and Comparative Examples 1-3)

[0091] The treatment agents for each carbon fiber precursor in Examples 2-24 and Comparative Examples 1-3 were prepared using the components shown in Table 1 and the same method as in Example 1.

[0092] It should be noted that the types and contents of amine derivatives (A), smoothing agents (B), and (poly)oxyalkylene derivatives (C) in the treatment agents of each example are shown in the "Amine Derivatives (A)" column, "Smoothing Agents (B)" column, and "(Poly)oxyalkylene Derivatives (C)" column of Table 1, respectively.

[0093] [Table 1]

[0094]

[0095] The details of the amine derivatives (A), smoothing agents (B), and (poly)oxyalkylene derivatives (C) in Table 1 are as follows.

[0096] (Amine derivative (A))

[0097] The types and mixing ratios of amine compounds (A1) and (A2) in the amine derivatives (A) of Table 1, as well as the types and molar addition of epoxides with 2 to 4 carbon atoms, are shown in the "Types and Mixing Ratios of Amine Compounds (parts by mass)" and "Types and Molar Addition of Epoxides" columns of Table 2, respectively.

[0098] In Table 2, "C8" refers to amine compounds with 8 carbon atoms in the hydrocarbon group. Similarly, "C16:1" refers to amine compounds with 16 carbon atoms in the hydrocarbon group and one unsaturated bond, and so on.

[0099] Compounds marked with an asterisk (*) in the upper right corner of the numbers refer to amine compounds (A1), and all others refer to amine compounds (A2). In Example 25, the amine compound present in amine derivative (A-9) is designated as amine compound (A1), and the amine compound present in amine derivative (A-10) is designated as amine compound (A2). EO refers to ethylene oxide, and PO refers to propylene oxide.

[0100] The amine derivatives (A-1), (A-3) to (A-8) were prepared by adding EO to a mixture of 1 mole of amine compounds (A1) and (A2).

[0101] Regarding the amine derivative (A-2), it was prepared by sequential block addition of EO and PO to a total of 1 mole of a mixture of amine compounds (A1) and (A2). All amine derivatives (A-1) to (A-10) were primary amines having straight-chain hydrocarbon groups.

[0102] It should be noted that the method for preparing amine derivatives (A-1) to (A-8) is not limited to the method of adding epoxides to a mixture of amine compounds. Alternatively, each amine compound can be added to an epoxide separately, and then they can be mixed together for preparation.

[0103] [Table 2]

[0104]

[0105] a-1: A compound formed by the addition of 15 moles of ethylene oxide and 10 moles of propylene oxide to 1 mole of stilbene-modified phenol.

[0106] a-2: A compound formed by the addition of 15 moles of ethylene oxide and 10 moles of propylene oxide to 1 mole of tristyrene-modified phenol.

[0107] (Smoothing Agent (B))

[0108] B-1: The kinematic viscosity at 25℃ is 650 mmHg. 2 / s, amino-modified silicone with an amino equivalent of 1800 g / mol

[0109] B-2: Kinematic viscosity at 25℃ is 90 mmHg. 2 The kinematic viscosity of amino-modified silicone B-3 at 25℃ is 4500 mm³ / s, with an amino equivalent of 5000 g / mol. 2 / s, amino-modified silicone with an amino equivalent of 1200 g / mol

[0110] B-4: Kinematic viscosity at 25℃ is 8000 mm. 2 / s, amino-modified silicone with an amino equivalent of 1000 g / mol

[0111] B-5: Kinematic viscosity at 25℃ is 350 mmHg 2 / s of dimethyl silicone

[0112] B-6: Di(dodecyl) ester of the ethylene oxide 2-molar adduct of bisphenol A

[0113] ((poly)oxyalkylene derivative (C))

[0114] C-1: A compound formed by the addition of 5 moles of ethylene oxide to 1 mole of 2-dodecanool.

[0115] C-2: Compounds formed by the addition of 9 moles of ethylene oxide to 1 mole of 2-tetradecanoic acid. Experimental Group 2 (Manufacturing of Synthetic Fibers and Carbon Fibers).

[0116] Synthetic fibers and carbon fibers were manufactured using an aqueous solution of the synthetic fiber treatment agent prepared in test group 1.

[0117] First, as step 1, the acrylic resin is wet-spun. Specifically, a copolymer consisting of 95% by mass acrylonitrile, 3.5% by mass methyl acrylate, and 1.5% by mass methacrylic acid with an intrinsic viscosity of 1.80 is dissolved in dimethylacetamide (DMAC) to prepare a spinning solution with a polymer concentration of 21.0% by mass and a viscosity of 500 poise at 60°C. The spinning solution is discharged in a coagulation bath of a 70% by mass aqueous solution of DMAC maintained at a spinning bath temperature of 35°C using a spinneret with an orifice diameter (inner diameter) of 0.075 mm and 12,000 orifices at a draw ratio of 0.8.

[0118] The solidified filaments were desolventized in a water washing tank and simultaneously stretched to 5 times their original length to produce a water-swollen acrylic fiber filament (raw fiber). For this acrylic fiber filament, the synthetic fiber treatment agent prepared in test group 1 was applied with a solid content of 1% by mass (excluding solvent). The application of the synthetic fiber treatment agent was carried out by impregnation with a 4% ion-exchange aqueous solution of the synthetic fiber treatment agent. Subsequently, the acrylic fiber filament was dried and densified using heated rollers at 130°C, then stretched 1.7 times between heated rollers at 170°C, and finally wound onto a filament tube using a winding device.

[0119] Next, as step 2, the filament is unwound from the wound carbon fiber precursor and subjected to refractory treatment for 1 hour in an air atmosphere using a refractory furnace with a temperature gradient of 230°C or higher and 270°C or lower. After that, it is wound onto a filament tube to obtain refractory filament (refractory fiber).

[0120] Next, as step 3, the filament is unwound from the wound refractory filament and fired in a carbonization furnace with a temperature gradient of 300°C to 1300°C under a nitrogen atmosphere to convert it into carbon fiber. Then, it is wound onto a filament tube to obtain carbon fiber.

[0121] Experimental Group 3 (Evaluation)

[0122] For the treatment agents of Examples 1-24 and Comparative Examples 1-3, the spinning bundle properties, fire-resistant bundle properties, and carbon fiber strength were evaluated according to the procedures described below.

[0123] (Spinning bundle properties)

[0124] Acrylic fiber yarn that had been treated with a synthetic fiber treatment agent in process 1 of test group 2 was passed through a heated roller at 130°C. The bundled state at this point was visually observed and evaluated according to the following criteria. The evaluation results are shown in the "Spinning Bundling" column of Table 1.

[0125] Evaluation criteria for spinning bundle properties

[0126] ◎(Good): The fibers are bundled together, the filament width is relatively narrow, and they are not entangled on the heating rollers, making operation completely problem-free.

[0127] ○ (Pass): The yarn is slightly loose and the yarn width is slightly wider, but it is not wrapped around the heating roller, and there are no problems with operability.

[0128] × (Unacceptable): Increased looseness and width of the yarn, leading to frequent yarn breakage due to winding around the heating roller, affecting operability.

[0129] (Fire-resistant clustering properties)

[0130] For the refractory fibers that underwent refractory treatment using process 2 of test group 2, the bundled state before being wound onto the filament tube was visually observed and evaluated according to the following criteria. The evaluation results are shown in the "Refractory Bundling" column of Table 1.

[0131] Evaluation criteria for fire-resistant clustering

[0132] ○ (Pass): Fibers are bundled, but there are no spaces within the fiber bundles.

[0133] × (Unacceptable): Fibers were not bundled, resulting in gaps within the fiber bundle and an increased fiber width.

[0134] (strength)

[0135] The strength of the carbon fibers obtained in process 3 of test group 2 was determined according to JIS R7606 (corresponding to international standard ISO11566:1996). Evaluation was conducted according to the following criteria. The evaluation results are shown in the "Strength" column of Table 1.

[0136] • Strength evaluation criteria

[0137] ◎(Good): Strength is above 4.0 GPa and less than 4.5 GPa

[0138] ○ (Qualified): Strength is above 3.5 GPa and less than 4.0 GPa

[0139] × (Unacceptable): Strength less than 3.5 GPa

[0140] According to the results in Table 1, the present invention can improve the spinning bundle properties of synthetic fibers. Furthermore, it can improve the fire-resistant bundle properties and the strength of carbon fibers.

Claims

1. A treatment agent for synthetic fibers, characterized in that, It contains the following amine derivative A and smoothing agent B. Amine derivative A: A compound formed by adding an epoxy alkane with 2 or more and 4 or fewer carbon atoms to a total of 1 mole of an amine compound A1 having a hydrocarbon group with 8 or more and 20 or fewer carbon atoms, which has a different number of carbon atoms than the hydrocarbon group of said amine compound A1. The smoothing agent B contains amino-modified silicone. When the total content of the amine derivative A and the smoothing agent B is set to 100% by mass, the amine derivative A is contained in a proportion of 3% by mass or more and 50% by mass or less, and the smoothing agent B is contained in a proportion of 50% by mass or more and 97% by mass or less.

2. The synthetic fiber treatment agent according to claim 1, wherein, The epoxide contains ethylene oxide.

3. The synthetic fiber treatment agent according to claim 1 or 2, further comprising the following polyoxyalkylene derivative C, Polyoxyalkylene derivative C: A compound formed by adding an epoxide having 2 or more and 4 or fewer carbon atoms to 1 mole of a monoaliphatic alcohol having a hydroxyl group at the β-position of an alkyl chain having 4 or more carbon atoms in a total ratio of 1 mole or more and 30 moles or less.

4. The synthetic fiber treatment agent according to claim 3, wherein, When the total content of the amine derivative A, the smoothing agent B, and the polyoxyalkylene derivative C is set to 100% by mass, the amine derivative A is contained in a proportion of 3% by mass or more and 40% by mass or less, the smoothing agent B is contained in a proportion of 20% by mass or more and 94% by mass or less, and the polyoxyalkylene derivative C is contained in a proportion of 3% by mass or more and 50% by mass or less.

5. The synthetic fiber treatment agent according to claim 1 or 2, wherein, The synthetic fiber is a carbon fiber precursor.

6. A synthetic fiber, characterized in that, It is coated with the synthetic fiber treatment agent as described in any one of claims 1 to 5.

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