Classifications

• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
  • D01F9/00—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments
  • D01F9/08—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments of inorganic material
  • D01F9/12—Carbon filaments; Apparatus specially adapted for the manufacture thereof
  • D01F9/14—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments
  • D01F9/20—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments from polyaddition, polycondensation or polymerisation products
  • D01F9/21—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments from polyaddition, polycondensation or polymerisation products from macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D01F9/22—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments from polyaddition, polycondensation or polymerisation products from macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds from polyacrylonitriles
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
  • D06M13/00—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment
  • D06M13/02—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment with hydrocarbons
  • D06M13/03—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment with hydrocarbons with unsaturated hydrocarbons, e.g. alkenes, or alkynes
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
  • D06M15/00—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment
  • D06M15/19—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment with synthetic macromolecular compounds
  • D06M15/37—Macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
  • D06M15/53—Polyethers
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
  • D06M2101/00—Chemical constitution of the fibres, threads, yarns, fabrics or fibrous goods made from such materials, to be treated
  • D06M2101/16—Synthetic fibres, other than mineral fibres
  • D06M2101/18—Synthetic fibres consisting of macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D06M2101/26—Polymers or copolymers of unsaturated carboxylic acids or derivatives thereof
  • D06M2101/28—Acrylonitrile; Methacrylonitrile

Definitions

• the present invention relates to a treatment agent for carbon fiber precursors and its uses. More specifically, the present invention relates to a treatment agent used in producing carbon fiber precursors, a carbon fiber precursor (hereinafter sometimes referred to as a precursor) using the treatment agent, and a method for producing carbon fiber using the carbon fiber precursor.
• a treatment agent used in producing carbon fiber precursors
• a carbon fiber precursor hereinafter sometimes referred to as a precursor
• a method for producing carbon fiber using the carbon fiber precursor a method for producing carbon fiber using the carbon fiber precursor.
• carbon fibers are widely used as reinforcing fibers for composite materials with plastics called matrix resins in aerospace applications, sports applications, general industrial applications, and the like.
• a typical method for producing carbon fibers is to convert a precursor into a flame-resistant fiber in an oxidizing atmosphere at 200 to 300° C., and then carbonize it in an inert atmosphere at 300 to 2000° C. During the firing process at high heat, fusion between single fibers occurs, which causes a problem of degrading the quality and grade of the obtained carbon fibers.
• silicone-based treating agents which have excellent heat resistance and excellent releasability due to smoothness between fibers, particularly amino-modified silicone-based treating agents that can further improve heat resistance through a crosslinking reaction, to the precursor, and these techniques are widely used industrially.
• the silicone-based treatment agent that has been attached falls off the fibers and becomes sticky, which accumulates on drying rollers, guides, etc. in the precursor manufacturing process, causing problems such as reduced operability, such as fibers curling up or breaking.
• a part of it forms silicon oxide in the oxidizing atmosphere of the flame-proofing process, and silicon nitride when nitrogen is used as an inert gas in the inert atmosphere of the carbonization process, and these scales accumulate, causing problems such as reduced operability and operating efficiency and damage to the firing furnace.
• An object of the present invention is to provide a treating agent for carbon fiber precursors that can stably suppress fusion between fibers during a flame retardant treatment process, a carbon fiber precursor using the treating agent, and a method for producing carbon fibers using the carbon fiber precursor.
• the present invention includes the following embodiments.
• a treatment agent for a carbon fiber precursor comprising a wax (A) and a surfactant (B).
• ⁇ 4> The treatment agent for carbon fiber precursors according to any one of ⁇ 1> to ⁇ 3>, wherein the wax (A) includes at least one selected from an animal wax, a vegetable wax, a polyolefin wax, a paraffin wax, a microcrystalline wax, and a Fischer-Tropsch wax.
• the surfactant (B) includes a surfactant having a hydrocarbon group having 6 to 40 carbon atoms.
• a method for producing a carbon fiber comprising: a flame-retardant treatment step of converting the carbon fiber precursor according to ⁇ 6> into a flame-retardant fiber in an oxidizing atmosphere at 200 to 300°C; and a carbonization treatment step of further carbonizing the flame-retardant fiber in an inert atmosphere at 300 to 2000°C.
• the carbon fiber precursor treatment agent of the present invention can stably suppress inter-fiber fusion during the flame-resistant treatment process of the carbon fiber precursor when a carbon fiber precursor produced by applying the treatment agent is used.
• the carbon fiber precursor of the present invention can stably suppress inter-fiber fusion during the flame-resistant treatment process. According to the carbon fiber production method of the present invention, inter-fiber fusion during the flame-resistant treatment process can be stably suppressed, and high-quality carbon fiber can be obtained.
• the treatment agent of the present invention contains a wax (A).
• the wax (A) is an organic substance that is solid at room temperature and becomes liquid when heated. From the viewpoint of achieving both bundling properties and anti-fusing properties, the wax (A) preferably has a melting point of 50 to 140° C.
• the upper limit of the melting point is more preferably 135° C., further preferably 130° C., and particularly preferably 120° C. Meanwhile, the lower limit of the melting point is more preferably 53° C., further preferably 55° C., and particularly preferably 60° C.
• the wax (A) examples include animal wax, vegetable wax, polyolefin wax, paraffin wax, microcrystalline wax, and Fischer-Tropsch wax.
• the wax (A) may be used alone or in combination of two or more kinds.
• Examples of animal waxes include beeswax, lanolin, and whale wax.
• Examples of vegetable waxes include carnauba wax, candelilla wax, rice wax, Japan wax, and jojoba oil.
• Examples of polyolefin waxes include polyethylene wax, oxidized polyethylene wax, acid-modified polyethylene wax, polypropylene wax, oxidized polypropylene wax, acid-modified polypropylene wax, polybutylene wax, oxidized polybutylene wax, acid-modified polybutylene wax, ethylene-acrylic acid copolymer wax, ethylene-vinyl acetate copolymer wax, acid-modified ethylene-vinyl acetate copolymer wax, ethylene-maleic anhydride copolymer wax, and propylene-maleic anhydride copolymer wax.
• the paraffin wax includes waxes containing normal paraffin as a main component.
• Microcrystalline waxes include waxes whose main component is isoparaffin.
• it is preferable to include at least one selected from beeswax, carnauba wax, candelilla wax, rice wax, oxidized polyethylene wax, acid-modified polyethylene wax, oxidized polypropylene wax, acid-modified polypropylene wax, and normal paraffin it is more preferable to include at least one selected from carnauba wax, candelilla wax, oxidized polyethylene wax, acid-modified polyethylene wax, and normal paraffin, and it is particularly preferable to include normal paraffin.
• the treatment agent of the present invention contains a surfactant (B).
• the surfactant (B) is not particularly limited, but examples thereof include nonionic surfactants, anionic surfactants, cationic surfactants, and amphoteric surfactants.
• the surfactant (B) preferably contains at least one selected from nonionic surfactants and anionic surfactants, and more preferably contains a nonionic surfactant, in that anti-fusing properties can be uniformly imparted.
• the surfactant (B) preferably contains a surfactant having a hydrocarbon group having 6 to 40 carbon atoms, in that anti-fusing properties can be uniformly imparted.
• the upper limit of the carbon number is more preferably 35, further preferably 30, and particularly preferably 20.
• the lower limit of the carbon number is more preferably 8, further preferably 10, and particularly preferably 12. Also, for example, 8 to 35 is more preferable, and 10 to 30 is more preferable.
• Nonionic surfactants include polyoxyalkylene linear alkyl ethers such as polyoxyethylene hexyl ether, polyoxyethylene heptyl ether, polyoxyethylene octyl ether, polyoxyethylene decyl ether, polyoxyethylene lauryl ether, polyoxyethylene tridecyl ether, polyoxyethylene tetradecyl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, and polyoxyethylene behenyl ether; polyoxyalkylene branched primary alkyl ethers such as polyoxyethylene 2-ethylhexyl ether, polyoxyethylene isocetyl ether, and polyoxyethylene isostearyl ether; polyoxyethylene 1-hexylhexyl ether, polyoxyethylene 1-octylhexyl ether, and polyoxyethylene Polyoxyalkylene secondary alkyl ethers such as 1-hexyl octyl ether, polyoxyethylene 1-pentyl
• polyoxyalkylene linear primary alkyl ethers in terms of being able to uniformly impart anti-fusing properties, it is preferable to include at least one selected from polyoxyalkylene linear primary alkyl ethers, polyoxyalkylene linear secondary alkyl ethers, polyoxyalkylene branched primary alkyl ethers, polyoxyalkylene branched secondary alkyl ethers, polyoxyalkylene alkylphenyl ethers, polyoxyalkylene alkylaryl phenyl ethers, and acetylene surfactants, and it is preferable to include at least one selected from polyoxyalkylene linear primary alkyl ethers, polyoxyalkylene linear secondary alkyl ethers, polyoxyalkylene branched primary alkyl ethers, and polyoxyalkylene branched secondary alkyl ethers.
• the number of carbon atoms in these alkyl groups is preferably 12 or more, more preferably 18 or more.
• the upper limit of the alkyl group is preferably 30, and even more preferably 25.
• the alkyl group is, for example, preferably 12 to 30, more preferably 18 to 25. It is preferable that the alkyl group includes a linear structure.
• the weight average molecular weight of the nonionic surfactant is preferably 2000 or less, more preferably 200 to 1800, more preferably 300 to 1500, and even more preferably 500 to 1000.
• One or more kinds of nonionic surfactants may be used.
• anionic surfactants include fatty acids (salts) such as stearic acid, arachidic acid, behenic acid, lignoceric acid, oleic acid, palmitic acid, sodium oleate, potassium palmitate, and triethanolamine oleate; hydroxyl group-containing carboxylic acids (salts) such as hydroxyacetic acid, potassium hydroxyacetate, lactic acid, and potassium lactate; polyoxyalkylene alkyl ether acetic acids (salts) such as polyoxyethylene tridecyl ether acetic acid (sodium salt); salts of carboxyl group-polysubstituted aromatic compounds such as potassium trimellitate and potassium pyromellitate; and alkylbenzene sulfonic acids such as dodecylbenzene sulfonic acid (sodium salt).
• fatty acids salts
• arachidic acid arachidic acid
• behenic acid lignoceric acid
• oleic acid palmitic acid
• phosphonic acids such as polyoxyalkylene alkyl ether sulfonic acids (salts) such as polyoxyethylene 2-ethylhexyl ether sulfonic acid (potassium salt); higher fatty acid amide sulfonic acids (salts) such as stearoyl methyl taurine (sodium), lauroyl methyl taurine (sodium), myristoyl methyl taurine (sodium), palmitoyl methyl taurine (sodium); N-acyl sarcosinic acids (salts) such as lauroyl sarcosinic acid (sodium); alkyl phosphonic acids (salts) such as octyl phosphonate (potassium salt); aromatic phosphonic acids (salts) such as phenyl phosphonate (potassium salt); 2-ethylhexyl phosphonate mono 2-ethylhexyl alkylphosphonic acid alkyl
• polyoxyalkylene alkyl ether acetates salts
• polyoxyalkylene alkyl ether sulfonic acids salts
• alkylbenzene sulfonic acids salts
• polyoxyalkylene alkyl ether sulfonic acids salts
• alkyl phosphate esters salts
• the number of carbon atoms in these alkyl groups is preferably 12 or more, and more preferably 18 or more.
• the upper limit of the alkyl group is preferably 30, and even more preferably 25.
• the alkyl group is preferably 12 to 30, and more preferably 18 to 25.
• cationic surfactants include lauryl trimethyl ammonium chloride, myristyl trimethyl ammonium chloride, palmityl trimethyl ammonium chloride, stearyl trimethyl ammonium chloride, oleyl trimethyl ammonium chloride, cetyl trimethyl ammonium chloride, behenyl trimethyl ammonium chloride, coconut oil alkyl trimethyl ammonium chloride, beef tallow alkyl trimethyl ammonium chloride, stearyl trimethyl ammonium bromide, coconut oil alkyl trimethyl ammonium bromide, cetyl trimethyl ammonium methosulfate, oleyl dimethylethyl ammonium ethosulfate, dioctyl dimethyl ammonium chloride, dilauryl dimethyl ammonium chloride, distearyl dimethyl ammonium chloride, and octadecyl diethyl methyl ammonium sulfate.
• (polyoxyalkylene) alkylamino ether salts such as (polyoxyethylene) lauryl amino ether lactate, stearyl amino ether lactate, di(polyoxyethylene) lauryl methyl amino ether dimethyl phosphate, di(polyoxyethylene) lauryl ethyl ammonium ethosulfate, di(polyoxyethylene) hardened beef tallow alkyl ethyl amine ethosulfate, di(polyoxyethylene) lauryl methyl ammonium dimethyl phosphate, di(polyoxyethylene) stearyl amine lactate; acyl amido alkyl quaternary ammonium salts such as N-(2-hydroxyethyl)-N,N-dimethyl-N-stearoyl amido propyl ammonium nitrate, lanolin fatty acid amido propyl ethyl dimethyl ammonium ethosulfate, lauroyl amido ethyl
• amphoteric surfactants include imidazoline-based amphoteric surfactants such as 2-undecyl-N,N-(hydroxyethylcarboxymethyl)-2-imidazoline sodium and 2-cocoyl-2-imidazolinium hydroxide-1-carboxyethyloxy disodium salt; betaine-based amphoteric surfactants such as 2-heptadecyl-N-carboxymethyl-N-hydroxyethylimidazolium betaine, lauryl dimethylaminoacetate betaine, alkyl betaine, amido betaine, and sulfobetaine; and amino acid-based amphoteric surfactants such as N-lauryl glycine, N-lauryl ⁇ -alanine, and N-stearyl ⁇ -alanine.
• imidazoline-based amphoteric surfactants such as 2-undecyl-N,N-(hydroxyethylcarboxymethyl)-2-imidazoline
• the treating agent for carbon fiber precursors of the present invention may further contain a modified silicone having a modifying group containing a nitrogen atom, in order to impart excellent smoothness between fibers.
• the modified silicone having a modified group containing a nitrogen atom is not particularly limited in type as long as the modified group contains a nitrogen atom.
• the modified group containing a nitrogen atom may be a modified group containing an amino bond or an imino bond (such as an amino group), or a modified group containing an amide bond (such as an amide group), or may be a modified group having a plurality of different bonds such as an amino bond and an amide bond.
• the modifying group containing a nitrogen atom preferably contains at least one selected from an amino group, an amide group, and a nitro group, and more preferably contains an amino group, in terms of excellent emulsion stability when emulsified in an aqueous system and excellent effects when used in combination with the wax (A).
• the modifying group containing a nitrogen atom may be bonded to a side chain of the silicone main chain, may be bonded to an end, or may be bonded to both.
• the molecule may contain a polyoxyalkylene group (e.g., a polyoxyethylene group, a polyoxypropylene group, a polyoxybutylene group, etc.).
• modified silicones having a modifying group containing a nitrogen atom include amino-modified silicones, amino polyether-modified silicones, amide-modified silicones, and amide polyether-modified silicones. At least one type selected from amino-modified silicones and amide-modified silicones is preferred, and amino-modified silicones are more preferred, in that they provide excellent emulsion stability when emulsified in a water-based system and are also effective when used in combination with wax (A).
• modified silicone having a modifying group containing a nitrogen atom one type of modified silicone may be used, or multiple modified silicones may be used in combination.
• the nitrogen atom content in the modified silicone having a nitrogen atom-containing modifying group is preferably 0.35 to 3.2% by weight, since this provides excellent emulsion stability when emulsified in an aqueous system, and also provides excellent effects of the present application when used in combination with wax (A).
• the upper limit of this content is more preferably 2.2% by weight, and even more preferably 1.3% by weight.
• the lower limit of this content is more preferably 0.37% by weight, and even more preferably 0.40% by weight. For example, 0.37 to 2.2% by weight is more preferable, and 0.40 to 1.3% by weight is even more preferable.
• the structure of the amino-modified silicone is not particularly limited. That is, the amino group, which is the modifying group, may be bonded to a side chain of the silicone main chain, or to an end, or may be bonded to both. In addition, the amino group may be of the monoamine type or polyamine type, and both may coexist in one molecule.
• the content of amino groups in the amino-modified silicone (hereinafter referred to as "amino weight %") is preferably 0.4 to 3.7 weight % in terms of excellent emulsion stability when emulsified in water and excellent effects of the present application when used in combination with wax (A).
• the upper limit of the content is more preferably 2.5 weight %, and even more preferably 1.5 weight %.
• the lower limit of the content is more preferably 0.42 weight %, and even more preferably 0.46 weight %. Also, for example, 0.42 to 2.5 weight % is more preferable, and 0.46 to 1.5 weight % is even more preferable.
• the kinetic viscosity at 25°C of the modified silicone having a modifying group containing a nitrogen atom is not particularly limited, but is preferably 100 to 15,000 mm 2 /s in terms of emulsion stability and uniform application to fibers.
• the upper limit of the kinetic viscosity is more preferably 10,000 mm 2 /s, and even more preferably 5,000 mm 2 /s.
• the lower limit of the kinetic viscosity is more preferably 500 mm 2 /s, and even more preferably 1,000 mm 2 /s. Also, for example, 500 to 10,000 mm 2 /s is more preferable, and 1,000 to 5,000 mm 2 /s is more preferable.
• the carbon fiber precursor treatment agent of the present invention contains wax (A) and surfactant (B). It is believed that the reason why the treatment agent contains wax (A) and surfactant (B) and can stably suppress the fusion between fibers in the flame retardant treatment process is that the surfactant (B) uniformly and evenly attaches the wax (A) to the fiber, thereby stably suppressing the fusion between fibers.
• the carbon fiber precursor treatment agent does not contain wax (A)
• the fusion prevention property is insufficient, and the fiber bundles are fused, or the fiber bundles are scummed or tarred, which deteriorates the spinning operability, and high-quality carbon fibers cannot be obtained.
• the surfactant (B) is not contained, the surface tension cannot be sufficiently reduced and the fiber bundles cannot be uniformly attached to the inside, so that uniform fusion prevention property cannot be obtained.
• the proportion of the wax (A) in the non-volatile content of the treatment agent of the present invention is not particularly limited, but from the viewpoint of anti-fusing properties, it is preferably 20 to 95% by weight.
• the upper limit of the weight proportion is more preferably 90% by weight, even more preferably 85% by weight, particularly preferably 83% by weight, and most preferably 80% by weight.
• the lower limit of the weight proportion is more preferably 25% by weight, even more preferably 28% by weight, particularly preferably 30% by weight, and most preferably 35% by weight. Also, for example, 25 to 90% by weight is more preferable, and 35 to 80% by weight is even more preferable.
• the non-volatile content refers to the amount of the treatment agent remaining on the aluminum sheet when 2.0 to 3.0 g of the treatment agent is spread evenly on an aluminum sheet ( ⁇ 12 cm) and dried at 110° C. under irradiation with an infrared lamp, and the fluctuation range of the volatile content over 150 seconds becomes 0.15%.
• the proportion of normal paraffin in the non-volatile content of the treatment agent is preferably 5 to 95% by weight from the viewpoint of anti-fusion properties.
• the upper limit of this proportion is more preferably 90% by weight, even more preferably 80% by weight, and particularly preferably 70% by weight.
• the lower limit of this proportion is more preferably 8% by weight, even more preferably 10% by weight, and particularly preferably 15% by weight. Also, for example, 8 to 90% by weight is more preferable, and 10 to 80% by weight is even more preferable.
• the proportion of the surfactant (B) in the non-volatile content of the treatment agent of the present invention is not particularly limited, but is preferably 5 to 80% by weight, in order to allow the wax (A) to be adhered uniformly and without unevenness to the fibers.
• the upper limit of this proportion is more preferably 50% by weight, even more preferably 45% by weight, particularly preferably 43% by weight, and most preferably 40% by weight.
• the lower limit of this proportion is more preferably 10% by weight, even more preferably 15% by weight, particularly preferably 17% by weight, and most preferably 20% by weight. Also, for example, 10 to 43% by weight is more preferable, and 15 to 45% by weight is even more preferable.
• the weight percentage of the nonionic surfactant in the nonvolatile content of the treatment agent is preferably 5 to 35% by weight from the viewpoint of emulsion stability.
• the upper limit of this weight percentage is more preferably 30% by weight, even more preferably 25% by weight, and especially preferably 20% by weight.
• the lower limit of this weight percentage is more preferably 7% by weight, even more preferably 9% by weight, and especially preferably 10% by weight. Also, for example, 7 to 35% by weight is more preferable, and 10 to 20% by weight is even more preferable.
• the proportion of the silicone in the non-volatile content of the treatment agent is not particularly limited, but is preferably 5 to 50% by weight in terms of providing excellent smoothness between fibers.
• the upper limit of this proportion is more preferably 47% by weight, even more preferably 45% by weight, particularly preferably 43% by weight, and most preferably 40% by weight.
• the lower limit of this proportion is more preferably 10% by weight, even more preferably 15% by weight, particularly preferably 17% by weight, and most preferably 20% by weight. Also, for example, 10 to 43% by weight is more preferable, and 15 to 45% by weight is even more preferable.
• the weight ratio (B/A) of the surfactant (B) to the wax (A) contained in the treatment agent of the present invention is not particularly limited, but is preferably 0.11 to 2.5 in that the surfactant (B) adheres the wax (A) uniformly and evenly to the fibers, thereby stably suppressing fusion between the fibers.
• the upper limit of this ratio is more preferably 2.3, even more preferably 2.0, particularly preferably 1.8, and most preferably 1.5.
• the lower limit of this ratio is more preferably 0.15, even more preferably 0.18, particularly preferably 0.20, and most preferably 0.25.
• 0.2 to 5.0 is more preferable, and 0.25 to 1.8 is even more preferable.
• the carbon fiber precursor treating agent of the present invention may contain other components in addition to the above-mentioned components, so long as the effects of the present invention are not impaired.
• examples of other components include antioxidants such as phenols, amines, sulfurs, phosphorus, and quinones; antistatic agents such as quaternary ammonium salt-type cationic surfactants and amine salt-type cationic surfactants; smoothing agents such as alkyl esters of higher alcohols and higher alcohol ethers; antibacterial agents; preservatives; rust inhibitors; solvents; and moisture absorbents.
• the treatment agent of the present invention may also contain modified silicones other than the modified silicones having a modifying group containing a nitrogen atom as described above, as long as the effect of the present invention is not impaired.
• modified silicones include epoxy modified silicones, polyether modified silicones, epoxy polyether modified silicones (see, for example, Patent No. 4616934), carbinol modified silicones, alkyl modified silicones, phenol modified silicones, methacrylate modified silicones, alkoxy modified silicones, and fluorine modified silicones.
• One type of modified silicone may be used, or multiple modified silicones may be used in combination.
• the treatment agent of the present invention may also contain one or more low molecular weight silicones.
• low molecular weight silicones include linear or cyclic silicones having 2 to 7 silicon atoms.
• Specific examples of low molecular weight silicones include octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, heptamethyloctyltrisiloxane, hexamethyldisiloxane, decamethyltetrasiloxane, and dodecamethylpentasiloxane.
• These low molecular weight silicones may be included as minor components of modified silicones having a modifying group containing a nitrogen atom.
• the content of the low molecular weight silicone in the treatment agent of the present invention is preferably 5 parts by weight or less per 100 parts by weight of the modified silicone having a modifying group containing a nitrogen atom.
• the wax (A), the surfactant (B), and, if necessary, the modified silicone having a modifying group containing a nitrogen atom are in a state of being dissolved, solubilized, emulsified or dispersed in water.
• the weight ratio of water and the weight ratio of non-volatile matter in the entire carbon fiber precursor treatment agent of the present invention are preferably 0.1 to 99.9% by weight in terms of the transportation cost when transporting the treatment agent and the handleability due to the emulsion viscosity.
• the upper limit of the ratio is more preferably 90% by weight, even more preferably 80% by weight, and particularly preferably 50% by weight.
• the lower limit of the weight ratio is more preferably 1% by weight, even more preferably 5% by weight, and particularly preferably 10% by weight. Also, for example, 1 to 80% by weight is more preferable, and 5 to 50% by weight is even more preferable.
• the carbon fiber precursor treatment agent of the present invention can be manufactured by mixing the components described above.
• the carbon fiber precursor treatment agent of the present invention can be suitably used as a treatment agent (precursor treatment agent) for acrylic fibers (precursors) for producing carbon fibers. It may also be used as a treatment agent for carbon fiber precursors other than precursors.
• the carbon fiber precursor of the present invention is obtained by adhering the above-mentioned treating agent for carbon fiber precursors to a carbon fiber precursor and spinning it into yarn.
• the method for producing carbon fibers of the present invention includes a flame-retardant treatment step of converting the carbon fiber precursor having the carbon fiber precursor treating agent adhered thereto into a flame-retardant fiber in an oxidizing atmosphere at 200 to 300°C, and a carbonization treatment step of further carbonizing the flame-retardant fiber in an inert atmosphere at 300 to 2000°C.
• the treatment agent for carbon fiber precursor of the present invention since the treatment agent for carbon fiber precursor of the present invention is used, fusion between fibers during the flame retardant treatment process can be stably suppressed, and high-quality carbon fibers can be produced.
• the spinning process is a process of spinning the carbon fiber precursor by adhering a treatment agent for carbon fiber precursor to the carbon fiber precursor, and preferably includes an adhering treatment process and a drawing process.
• the adhesion treatment step is a step of adhering a treatment agent for carbon fiber precursors after spinning the carbon fiber precursors. That is, the treatment agent for carbon fiber precursors is adhered to the carbon fiber precursors in the adhesion treatment step.
• the high-ratio stretching after the adhesion treatment step is particularly called the "stretching step".
• the stretching step may be a wet heat stretching method using high-temperature steam or a dry heat stretching method using a heated roller.
• the stretching ratio in the stretching step is preferably 2 to 20 times the total stretching ratio of the carbon fiber precursors immediately after spinning.
• the precursor is preferably composed of acrylic fibers mainly composed of polyacrylonitrile obtained by copolymerizing at least 95 mol% or more of acrylonitrile and 5 mol% or less of a flame retardant promoting component.
• a flame retardant promoting component a vinyl group-containing compound that is copolymerizable with acrylonitrile can be suitably used.
• the single fiber fineness of the precursor but it is preferably 0.1 to 2.0 dtex in terms of the balance between performance and production costs.
• the number of single fibers that make up the precursor fiber bundle is preferably 1,000 to 96,000 in terms of the balance between performance and production costs.
• the carbon fiber precursor treatment agent of the present invention may be applied to the carbon fiber precursor at any stage in the carbon fiber manufacturing process, but it is preferable to apply it once before the drawing process. It may be applied at any stage before the drawing process, for example immediately after spinning. It may also be applied at any stage after the drawing process, for example immediately after the drawing process, at the winding stage, or immediately before the flame retardant treatment process. As for the application method, it may be applied using a roller or the like, or it may be applied by a dipping method, spraying method, etc.
• the application rate of the carbon fiber precursor treatment agent is preferably 0.1 to 5 wt. % of the weight of the carbon fiber precursor, and more preferably 0.3 to 1.5 wt. %, in order to strike a balance between obtaining the effect of preventing fusion between fibers and preventing deterioration of the quality of the carbon fiber due to the tarred products of the treatment agent in the carbonization process.
• the application rate of the carbon fiber precursor treatment agent here is defined as the percentage of the weight of the non-volatile matter attached to the carbon fiber precursor treatment agent relative to the weight of the carbon fiber precursor.
• the flame-retardant treatment process is a process in which the carbon fiber precursor to which the carbon fiber precursor treatment agent is attached is converted into a flame-retardant fiber in an oxidizing atmosphere at 200 to 300°C.
• the oxidizing atmosphere is usually an air atmosphere.
• the temperature of the oxidizing atmosphere is preferably 230 to 280°C.
• the acrylic fiber after the attachment treatment is heat-treated for 20 to 100 minutes (preferably 30 to 60 minutes) while applying a tension of a draw ratio of 0.90 to 1.10 (preferably 0.95 to 1.05).
• intramolecular cyclization and oxygen addition to the rings are carried out to produce a flame-retardant fiber with a flame-retardant structure.
• the carbonization process is a process in which the flame-resistant fiber is further carbonized in an inert atmosphere at 300 to 2000°C.
• the flame-resistant fiber is heat-treated for several minutes in an inert atmosphere of nitrogen, argon, etc., while applying a tension with a draw ratio of 0.95 to 1.05 to the first carbonization process, thereby performing a second carbonization process, and the flame-resistant fiber is carbonized.
• the control of the heat treatment temperature in the second carbonization process it is preferable to set the maximum temperature to 1000°C or higher (preferably 1000 to 2000°C) while applying a temperature gradient. This maximum temperature is appropriately selected and determined depending on the desired properties of the carbon fiber (tensile strength, elastic modulus, etc.).
• a graphitization process can be carried out following the carbonization process.
• the graphitization process is usually carried out in an inert atmosphere such as nitrogen or argon, while applying tension to the fiber obtained in the carbonization process, at a temperature of 2000 to 3000°C.
• the carbon fibers obtained in this way can be surface-treated to increase the adhesive strength with the matrix resin when made into a composite material, depending on the purpose.
• Gas-phase or liquid-phase treatment can be used as the surface treatment method, and from the viewpoint of productivity, liquid-phase treatment using an electrolyte such as an acid or alkali is preferred.
• various sizing agents that are highly compatible with the matrix resin can be added to improve the processability and handling of the carbon fibers.
• the application rate of the carbon fiber precursor treatment agent was calculated by an ethanol extraction method using a Soxhlet extractor. However, for the treatment agent containing silicone, the application rate was calculated by the following method.
• the carbon fiber precursor after the treatment agent was applied was alkali-fused with potassium hydroxide/sodium butyrate, dissolved in water, and adjusted to pH 1 with hydrochloric acid. Sodium sulfite and ammonium molybdate were added to this to develop color, and the silicon content was determined by colorimetry (wavelength 815 m ⁇ ) of silicomolybdenum blue.
• the application rate (wt%) of the treatment agent for carbon fiber precursor was calculated using the silicon content determined here and the silicon content in the treatment agent previously determined by the same method.
• ⁇ Many loose fibers and broken fibers are observed, and the bundling ability is poor.
• ⁇ Abrasion resistance> A carbon fiber precursor strand (12K) was rubbed 1000 times at a tension of 50 g through three mirror-finish chrome-plated stainless steel needles arranged in a zigzag pattern using a TM-type frictional embracing force tester TM-200 (manufactured by Daiei Scientific Instruments Co., Ltd.) (reciprocating speed: 300 times/min), and the state of fluffing of the carbon fiber precursor strand was visually evaluated according to the following criteria. ⁇ : No fuzzing was observed, just like before abrasion, and abrasion resistance was very excellent. ⁇ : Only a few fluffs are observed, and the abrasion resistance is excellent. ⁇ : There is a little bit of fluff and the abrasion resistance is a little poor. ⁇ : Much fuzz, significant single yarn breakage, and poor abrasion resistance.
• Example 1 In order to obtain the non-volatile composition of the treatment agent shown in Table 1, a 2L SUS autoclave equipped with a high-speed homogenizer was charged with wax A-1, surfactants B-1 and B-4, and pressurized with nitrogen gas to 0.3 MPa and released three times to completely replace the air in the autoclave with nitrogen gas, and then the contents were heated to 150 ° C. while stirring at high speed with a high-speed homogenizer, and mixed by stirring for 1 hour. Next, hot water heated to 150 ° C. was poured from another SUS autoclave attached to the top of the autoclave containing the wax, etc., for 2 hours, and dropped into the autoclave containing the wax, etc., to cause phase inversion emulsification.
• the mixture was stirred at 150 ° C. for 1 hour, then cooled to 80 ° C., the autoclave was released to normal pressure, and further cooled to 40 ° C. to prepare a treatment agent for carbon fiber precursors with a non-volatile concentration of 20 wt%.
• the weight percentage of wax A-1 in the nonvolatile content of the treatment agent was 75% by weight, the weight percentage of surfactant B-1 was 20% by weight, and the weight percentage of surfactant B-4 was 5% by weight.
• the prepared treatment agent was then further diluted with water to obtain a diluted solution having a non-volatile content of 3.0% by weight.
• the dilution solution was attached to the raw material acrylic fiber of the carbon fiber precursor obtained by copolymerizing 97 mol% acrylonitrile and 3 mol% itaconic acid so that the non-volatile content of the treatment agent was 1.0 wt%.
• a carbon fiber precursor was produced through a drawing process (steam drawing, drawing ratio 2.1 times) (single fiber fineness 0.8 dtex, 24,000 filaments). This carbon fiber precursor was flame-resistant treated in a flame-resistant furnace at 250°C for 60 minutes to obtain a flame-resistant fiber. The flame-resistant fiber was then calcined in a carbonization furnace having a temperature gradient of 300 to 1400°C under a nitrogen atmosphere to convert it into a carbon fiber.
• Table 1 The evaluation results of each characteristic value are shown in Table 1.
• Examples 2 to 32 Carbon fiber precursors and carbon fibers after the treatment agent was applied were obtained in the same manner as in Example 1, except that the treatment agent was adjusted so that the non-volatile composition of the treatment agent was as shown in Tables 1 to 3. The evaluation results of each characteristic value are shown in Tables 1 to 3.
• Comparative Examples 1 to 6 and 17 For Comparative Examples 1 to 6 and 17, each component and water were added and mixed with stirring so as to obtain the non-volatile composition of the treatment agent shown in Tables 4 and 5, to prepare a treatment agent for carbon fiber precursors having a non-volatile concentration of 20% by weight. The prepared treatment agent was then further diluted with water to obtain a diluted solution having a non-volatile content of 3.0% by weight.
• the dilution solution was attached to the raw material acrylic fiber of the carbon fiber precursor obtained by copolymerizing 97 mol% acrylonitrile and 3 mol% itaconic acid so as to have an application rate of 1.0%, and a carbon fiber precursor was produced through a drawing process (steam drawing, drawing ratio 2.1 times) (single fiber fineness 0.8 dtex, 24,000 filaments).
• This carbon fiber precursor was flame-resistant treated in a flame-resistant furnace at 250 ° C for 60 minutes to obtain a flame-resistant fiber. Then, it was converted into a carbon fiber by baking in a carbonization furnace having a temperature gradient of 300 to 1400 ° C under a nitrogen atmosphere.
• Tables 4 and 5 The evaluation results of each characteristic value are shown in Tables 4 and 5.
• Comparative Examples 7 to 16 Using the respective treatment agents of Comparative Examples 7 to 16 shown in Tables 4 and 5, Comparative Examples 7 to 14 were heated to above the melting point and uniformly dissolved, and Comparative Examples 15 and 16 were heated at 30°C to attach the agent to the raw material acrylic fiber of the carbon fiber precursor obtained by copolymerizing 97 mol% acrylonitrile and 3 mol% itaconic acid by dip oiling so that the application rate was 1.0%, and a carbon fiber precursor was produced through a drawing process (steam drawing, drawing ratio 2.1 times) (single fiber fineness 0.8 dtex, 24,000 filaments).
• This carbon fiber precursor was subjected to a flame-resistant treatment in a flame-resistant furnace at 250°C for 60 minutes to obtain a flame-resistant fiber. Subsequently, the flame-resistant fiber was calcined in a carbonization furnace having a temperature gradient of 300 to 1400°C under a nitrogen atmosphere to convert it into a carbon fiber.
• the evaluation results of each characteristic value are shown in Tables 4 and 5.
• the treatment agents of Comparative Examples 15 and 16 had poor spinning operability, and flame-retardant fibers and carbon fibers suitable for evaluation could not be obtained, so that evaluation of fusion prevention properties, abrasion resistance, and carbon fiber strength could not be performed.
• Wax A-1 Beeswax (melting point: 65°C)
• Wax A-2 Carnauba wax (melting point: 83°C, acid value: 8.3 mgKOH/g)
• Wax A-3 Candelilla wax (melting point: 71°C, acid value: 17.1 mgKOH/g)
• Wax A-4 Polyethylene wax (melting point: 130°C)
• Wax A-5 Oxidized polyethylene wax (melting point: 138°C, acid value: 30 mgKOH/g)
• Wax A-6 Paraffin wax 135F (melting point: 57°C)
• Wax A-7 Paraffin wax 150F (melting point: 66°C)
• the carbon fiber precursor treatment agents of the examples were excellent in preventing fusion, since they were treatment agents for carbon fiber precursors containing the wax (A) and the surfactant (B).
• the wax (A) was not contained (Comparative Examples 1 to 6, 17)
• the surfactant (B) was not contained (Comparative Examples 7 to 14)
• the spinning operability was poor and the agent could not be used as a treatment agent for carbon fiber precursors (Comparative Examples 2 to 6, 15 to 17), or the anti-fusing property was poor (Comparative Examples 1, 7 to 14), and the problem of the present application could not be solved.
• the carbon fiber precursor treatment agent of the present invention is a treatment agent used when producing a carbon fiber precursor, and is useful for producing high-quality carbon fibers.
• the carbon fiber precursor of the present invention is imparted with the treatment agent of the present invention, and is useful for producing high-quality carbon fibers. High-quality carbon fibers can be obtained by the carbon fiber production method of the present invention.

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