JP4167193B2 - Carbon fiber manufacturing method - Google Patents
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- JP4167193B2 JP4167193B2 JP2004056011A JP2004056011A JP4167193B2 JP 4167193 B2 JP4167193 B2 JP 4167193B2 JP 2004056011 A JP2004056011 A JP 2004056011A JP 2004056011 A JP2004056011 A JP 2004056011A JP 4167193 B2 JP4167193 B2 JP 4167193B2
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- 229920000049 Carbon (fiber) Polymers 0.000 title claims description 59
- 239000004917 carbon fiber Substances 0.000 title claims description 59
- 238000004519 manufacturing process Methods 0.000 title claims description 31
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 title claims description 31
- 229920005992 thermoplastic resin Polymers 0.000 claims description 84
- 239000007833 carbon precursor Substances 0.000 claims description 83
- 239000000835 fiber Substances 0.000 claims description 76
- 229920001169 thermoplastic Polymers 0.000 claims description 60
- 239000004416 thermosoftening plastic Substances 0.000 claims description 60
- 239000002243 precursor Substances 0.000 claims description 59
- 239000004745 nonwoven fabric Substances 0.000 claims description 54
- 238000000034 method Methods 0.000 claims description 30
- 239000000203 mixture Substances 0.000 claims description 28
- 239000007789 gas Substances 0.000 claims description 24
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 16
- NNBZCPXTIHJBJL-UHFFFAOYSA-N decalin Chemical compound C1CCCC2CCCCC21 NNBZCPXTIHJBJL-UHFFFAOYSA-N 0.000 claims description 16
- 239000000155 melt Substances 0.000 claims description 16
- 239000001301 oxygen Substances 0.000 claims description 16
- 229910052760 oxygen Inorganic materials 0.000 claims description 16
- 239000011295 pitch Substances 0.000 claims description 14
- 230000006641 stabilisation Effects 0.000 claims description 14
- 238000011105 stabilization Methods 0.000 claims description 14
- ZCYVEMRRCGMTRW-UHFFFAOYSA-N 7553-56-2 Chemical compound [I] ZCYVEMRRCGMTRW-UHFFFAOYSA-N 0.000 claims description 11
- 239000011630 iodine Substances 0.000 claims description 11
- 229910052740 iodine Inorganic materials 0.000 claims description 11
- -1 polycarbodiimide Substances 0.000 claims description 9
- PXXNTAGJWPJAGM-UHFFFAOYSA-N vertaline Natural products C1C2C=3C=C(OC)C(OC)=CC=3OC(C=C3)=CC=C3CCC(=O)OC1CC1N2CCCC1 PXXNTAGJWPJAGM-UHFFFAOYSA-N 0.000 claims description 8
- 230000008569 process Effects 0.000 claims description 7
- WSSSPWUEQFSQQG-UHFFFAOYSA-N 4-methyl-1-pentene Chemical compound CC(C)CC=C WSSSPWUEQFSQQG-UHFFFAOYSA-N 0.000 claims description 6
- 238000004090 dissolution Methods 0.000 claims description 6
- 239000011302 mesophase pitch Substances 0.000 claims description 6
- 229920001577 copolymer Polymers 0.000 claims description 5
- 239000004698 Polyethylene Substances 0.000 claims description 4
- 239000004642 Polyimide Substances 0.000 claims description 4
- 238000010000 carbonizing Methods 0.000 claims description 4
- 229920002239 polyacrylonitrile Polymers 0.000 claims description 4
- 229920000573 polyethylene Polymers 0.000 claims description 4
- 229920001721 polyimide Polymers 0.000 claims description 4
- 229920003235 aromatic polyamide Polymers 0.000 claims description 3
- 239000004760 aramid Substances 0.000 claims description 2
- 238000004898 kneading Methods 0.000 description 18
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 16
- 239000006185 dispersion Substances 0.000 description 15
- 239000011261 inert gas Substances 0.000 description 12
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 10
- 238000003763 carbonization Methods 0.000 description 7
- 229910052757 nitrogen Inorganic materials 0.000 description 7
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 6
- 229910052786 argon Inorganic materials 0.000 description 5
- 238000005979 thermal decomposition reaction Methods 0.000 description 5
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 4
- 239000005977 Ethylene Substances 0.000 description 4
- 238000004220 aggregation Methods 0.000 description 4
- 230000002776 aggregation Effects 0.000 description 4
- 238000001879 gelation Methods 0.000 description 4
- 238000005087 graphitization Methods 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 4
- 125000000391 vinyl group Chemical group [H]C([*])=C([H])[H] 0.000 description 4
- NIXOWILDQLNWCW-UHFFFAOYSA-M Acrylate Chemical compound [O-]C(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-M 0.000 description 3
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 3
- 238000007664 blowing Methods 0.000 description 3
- 239000001569 carbon dioxide Substances 0.000 description 3
- 229910002092 carbon dioxide Inorganic materials 0.000 description 3
- 239000002131 composite material Substances 0.000 description 3
- 229910001882 dioxygen Inorganic materials 0.000 description 3
- 230000004927 fusion Effects 0.000 description 3
- 239000000178 monomer Substances 0.000 description 3
- 238000009987 spinning Methods 0.000 description 3
- 229920002554 vinyl polymer Polymers 0.000 description 3
- VXNZUUAINFGPBY-UHFFFAOYSA-N 1-Butene Chemical compound CCC=C VXNZUUAINFGPBY-UHFFFAOYSA-N 0.000 description 2
- LIKMAJRDDDTEIG-UHFFFAOYSA-N 1-hexene Chemical compound CCCCC=C LIKMAJRDDDTEIG-UHFFFAOYSA-N 0.000 description 2
- KWKAKUADMBZCLK-UHFFFAOYSA-N 1-octene Chemical compound CCCCCCC=C KWKAKUADMBZCLK-UHFFFAOYSA-N 0.000 description 2
- WKBOTKDWSSQWDR-UHFFFAOYSA-N Bromine atom Chemical compound [Br] WKBOTKDWSSQWDR-UHFFFAOYSA-N 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- UFWIBTONFRDIAS-UHFFFAOYSA-N Naphthalene Chemical compound C1=CC=CC2=CC=CC=C21 UFWIBTONFRDIAS-UHFFFAOYSA-N 0.000 description 2
- 239000004697 Polyetherimide Substances 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 2
- GDTBXPJZTBHREO-UHFFFAOYSA-N bromine Substances BrBr GDTBXPJZTBHREO-UHFFFAOYSA-N 0.000 description 2
- 229910052794 bromium Inorganic materials 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 229910001873 dinitrogen Inorganic materials 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 238000003384 imaging method Methods 0.000 description 2
- 238000002074 melt spinning Methods 0.000 description 2
- 239000005011 phenolic resin Substances 0.000 description 2
- 229920001601 polyetherimide Polymers 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 229920000098 polyolefin Polymers 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 230000000630 rising effect Effects 0.000 description 2
- 230000000087 stabilizing effect Effects 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 239000004711 α-olefin Substances 0.000 description 2
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 description 1
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 1
- OYUNTGBISCIYPW-UHFFFAOYSA-N 2-chloroprop-2-enenitrile Chemical compound ClC(=C)C#N OYUNTGBISCIYPW-UHFFFAOYSA-N 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- CERQOIWHTDAKMF-UHFFFAOYSA-N Methacrylic acid Chemical compound CC(=C)C(O)=O CERQOIWHTDAKMF-UHFFFAOYSA-N 0.000 description 1
- 239000004793 Polystyrene Substances 0.000 description 1
- 229920000297 Rayon Polymers 0.000 description 1
- XTXRWKRVRITETP-UHFFFAOYSA-N Vinyl acetate Chemical compound CC(=O)OC=C XTXRWKRVRITETP-UHFFFAOYSA-N 0.000 description 1
- 125000005907 alkyl ester group Chemical group 0.000 description 1
- 150000004945 aromatic hydrocarbons Chemical class 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 239000003245 coal Substances 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000000280 densification Methods 0.000 description 1
- 238000004821 distillation Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 125000001495 ethyl group Chemical group [H]C([H])([H])C([H])([H])* 0.000 description 1
- 230000009477 glass transition Effects 0.000 description 1
- 239000011357 graphitized carbon fiber Substances 0.000 description 1
- 229910052736 halogen Inorganic materials 0.000 description 1
- 150000002367 halogens Chemical class 0.000 description 1
- 229920001903 high density polyethylene Polymers 0.000 description 1
- 239000004700 high-density polyethylene Substances 0.000 description 1
- 229920000092 linear low density polyethylene Polymers 0.000 description 1
- 239000004707 linear low-density polyethylene Substances 0.000 description 1
- 239000004973 liquid crystal related substance Substances 0.000 description 1
- 229920001684 low density polyethylene Polymers 0.000 description 1
- 239000004702 low-density polyethylene Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 229920001179 medium density polyethylene Polymers 0.000 description 1
- 239000004701 medium-density polyethylene Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 1
- 229910052753 mercury Inorganic materials 0.000 description 1
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- TVMXDCGIABBOFY-UHFFFAOYSA-N n-Octanol Natural products CCCCCCCC TVMXDCGIABBOFY-UHFFFAOYSA-N 0.000 description 1
- 125000004108 n-butyl group Chemical group [H]C([H])([H])C([H])([H])C([H])([H])C([H])([H])* 0.000 description 1
- 150000002894 organic compounds Chemical class 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920003229 poly(methyl methacrylate) Polymers 0.000 description 1
- 229920002492 poly(sulfone) Polymers 0.000 description 1
- 229920000058 polyacrylate Polymers 0.000 description 1
- 229920001230 polyarylate Polymers 0.000 description 1
- 239000004417 polycarbonate Substances 0.000 description 1
- 229920000515 polycarbonate Polymers 0.000 description 1
- 229920000728 polyester Polymers 0.000 description 1
- 229920005638 polyethylene monopolymer Polymers 0.000 description 1
- 229920000193 polymethacrylate Polymers 0.000 description 1
- 239000004926 polymethyl methacrylate Substances 0.000 description 1
- 229920002223 polystyrene Polymers 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- QQONPFPTGQHPMA-UHFFFAOYSA-N propylene Natural products CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 description 1
- 125000004805 propylene group Chemical group [H]C([H])([H])C([H])([*:1])C([H])([H])[*:2] 0.000 description 1
- 238000000197 pyrolysis Methods 0.000 description 1
- 239000002964 rayon Substances 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 229920001567 vinyl ester resin Polymers 0.000 description 1
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Description
本発明は炭素繊維を製造する方法に関する。更に詳しくは、極細炭素繊維、具体的には繊維径が１μｍ未満である炭素繊維を製造する方法に関する。 The present invention relates to a method for producing carbon fibers. More specifically, the present invention relates to a method for producing ultrafine carbon fibers, specifically, carbon fibers having a fiber diameter of less than 1 μm.
極細炭素繊維を製造する方法としては、メルトブロー法によるピッチ系炭素繊維の製造方法が開示されている。例えばパイプ状の紡糸ピッチノズルの周囲に同心円状に配置したガス流路管から気体を噴出させることにより、吐出された繊維状ピッチの細径化を図る方法（例えば、特許文献１を参照。）、ピッチ吐出ノズル列の両側にスリット状の気体噴出孔を設け、噴出孔から噴出したピッチに接触させることで繊維状ピッチの細径化を図る方法（例えば、特許文献２を参照。）などがある。これらの方法では、従来よりも繊維径の細い炭素繊維を製造することができるが、これらの方法で得られる炭素繊維の繊維径は平均で１〜５μｍ程度であり、これよりも細い極細炭素繊維を得ることは実質上困難であった。 As a method for producing ultrafine carbon fibers, a method for producing pitch-based carbon fibers by a melt blow method is disclosed. For example, a method of reducing the diameter of the discharged fibrous pitch by ejecting gas from a gas flow channel tube arranged concentrically around a pipe-shaped spinning pitch nozzle (see, for example, Patent Document 1). A method of reducing the diameter of the fibrous pitch by providing slit-like gas ejection holes on both sides of the pitch discharge nozzle row and making contact with the pitch ejected from the ejection holes (for example, see Patent Document 2). is there. In these methods, carbon fibers having a smaller fiber diameter than conventional ones can be produced, but the average fiber diameter of the carbon fibers obtained by these methods is about 1 to 5 μm, and an ultrafine carbon fiber thinner than this. It was practically difficult to obtain.
一方で、極細炭素繊維を製造する方法として、フェノール樹脂とポリエチレンとの複合繊維から極細炭素繊維を製造する方法（例えば、特許文献３を参照）が開示されている。 On the other hand, as a method for producing an ultrafine carbon fiber, a method for producing an ultrafine carbon fiber from a composite fiber of a phenol resin and polyethylene (see, for example, Patent Document 3) is disclosed.
該方法の場合、繊維径が数百ｎｍの極細炭素繊維を得ることができるが、フェノール樹脂は完全非晶であるため、配向形成しにくく、且つ難黒鉛化性であるため、得られる極細炭素繊維の強度は十分なものでは無く、弾性率の発現も期待できない等の問題があった。また、この方法で得られた極細炭素繊維は短繊維であって、不織布状の形態を保持させることが困難であった。 In the case of this method, an ultrafine carbon fiber having a fiber diameter of several hundreds nm can be obtained. However, since the phenol resin is completely amorphous, it is difficult to form an orientation and is hardly graphitized. The strength of the fiber is not sufficient, and there is a problem that the elastic modulus cannot be expected. Moreover, the ultrafine carbon fiber obtained by this method is a short fiber, and it was difficult to maintain a non-woven form.
本発明の目的は、上記従来技術では未だ達成できていなかった、極細炭素繊維からなる不織布、具体的には気孔率が６０％以上である不織布の製造方法を提供することにある。 An object of the present invention is to provide a method for producing a non-woven fabric made of ultrafine carbon fibers, specifically a non-woven fabric having a porosity of 60% or more, which has not yet been achieved by the above prior art.
本発明者らは上記従来技術に鑑み鋭意検討を重ねた結果、本発明を完成するに至った。即ち、本発明の目的は、
（１）熱可塑性樹脂１００重量部並びにピッチ、ポリアクリロニトリル、ポリカルボジイミド、ポリイミド、ポリベンゾアゾールおよびアラミドよりなる群から選ばれる少なくとも１種の熱可塑性炭素前駆体１〜１５０重量部からなる混合物から前駆体繊維を形成する工程、
（２）前駆体繊維を、沃素と酸素との混合ガス雰囲気下で安定化処理に付して、１００℃の熱デカリンへの溶解量が５０ｗｔ％未満である安定化前駆体繊維を形成する工程、
（３）安定化前駆体繊維から熱可塑性樹脂を除去して繊維状炭素前駆体を形成する工程、
（４）繊維状炭素前駆体を炭素化もしくは黒鉛化する工程、
を経る、炭素繊維の製造方法によって達成することができる。
As a result of intensive studies in view of the above prior art, the present inventors have completed the present invention. That is, the object of the present invention is to
(1) Precursor from a mixture comprising 1 to 150 parts by weight of a thermoplastic resin and 100 parts by weight of a thermoplastic resin and at least one thermoplastic carbon precursor selected from the group consisting of pitch, polyacrylonitrile, polycarbodiimide, polyimide, polybenzoazole and aramid Forming a body fiber,
(2) A step of subjecting the precursor fiber to a stabilization treatment in a mixed gas atmosphere of iodine and oxygen to form a stabilized precursor fiber having a dissolution amount in hot decalin at 100 ° C. of less than 50 wt%. ,
(3) a step of removing the thermoplastic resin from the stabilized precursor fiber to form a fibrous carbon precursor;
(4) a step of carbonizing or graphitizing the fibrous carbon precursor,
It can achieve by the manufacturing method of carbon fiber which goes through.
本発明によれば、繊維の分岐構造が少ない気孔率が６０％以上である極細炭素繊維からなる不織布を、効率的かつ安価に製造することができる。得られる極細炭素繊維からなる不織布は、高機能フィルター、電池用電極基材等に利用することができ、その工業的意義は大きい。 ADVANTAGE OF THE INVENTION According to this invention, the nonwoven fabric which consists of an ultra-fine carbon fiber with a porosity of 60% or more with few fiber branching structures can be manufactured efficiently and inexpensively. The obtained non-woven fabric made of ultrafine carbon fibers can be used for a high-functional filter, a battery electrode substrate, and the like, and has great industrial significance.
以下、本発明を（１）熱可塑性樹脂、（２）熱可塑性炭素前駆体、（３）熱可塑性樹脂と熱可塑性炭素前駆体からなる混合物の製造、（４）炭素繊維を製造する方法、（５）炭素繊維からなる不織布の順に詳細に説明する。
（１）熱可塑性樹脂
本発明で使用する熱可塑性樹脂は、安定化前駆体繊維を製造後、容易に除去される必要がある。このため、酸素または不活性ガス雰囲気下、３５０℃以上６００℃未満の温度で５時間保持することで、初期重量の１５ｗｔ％以下、より好ましくは１０ｗｔ％以下、さらには５ｗｔ％以下にまで分解する熱可塑性樹脂を用いることが好ましい。このような熱可塑性樹脂として、ポリオレフィン、ポリメタクリレート、ポリメチルメタクリレート等のポリアクリレート系ポリマー、ポリスチレン、ポリカーボネート、ポリアリレート、ポリエステルカーボネート、ポリサルホン、ポリイミド、ポリエーテルイミド等が好ましく使用される。これらの中でもガス透過性が高く、容易に熱分解しうる熱可塑性樹脂として、例えば下記式（Ｉ）で表されるポリオレフィン系の熱可塑性樹脂やポリエチレンなどが好ましく使用される。
Hereinafter, the present invention comprises (1) a thermoplastic resin, (2) a thermoplastic carbon precursor, (3) production of a mixture comprising a thermoplastic resin and a thermoplastic carbon precursor, (4) a method for producing carbon fiber, ( 5) It demonstrates in detail in the order of the nonwoven fabric which consists of carbon fibers.
(1) Thermoplastic resin The thermoplastic resin used in the present invention needs to be easily removed after the production of the stabilized precursor fiber. For this reason, it is decomposed | disassembled to 15 wt% or less of the initial weight, more preferably 10 wt% or less, and further 5 wt% or less by hold | maintaining for 5 hours at the temperature of 350 degreeC or more and less than 600 degreeC in oxygen or inert gas atmosphere. It is preferable to use a thermoplastic resin. As such a thermoplastic resin, a polyacrylate polymer such as polyolefin, polymethacrylate, polymethylmethacrylate, polystyrene, polycarbonate, polyarylate, polyester carbonate, polysulfone, polyimide, polyetherimide and the like are preferably used. Among these, as a thermoplastic resin that has high gas permeability and can be easily thermally decomposed, for example, a polyolefin-based thermoplastic resin represented by the following formula (I) or polyethylene is preferably used.
上記式（Ｉ）で表される化合物の具体的な例としては、ポリ−４−メチルペンテン−１やポリ−４−メチルペンテン−１の共重合体、例えばポリ−４−メチルペンテン−１にビニル系モノマーが共重合したポリマーなどや、ポリエチレンを例示することができ、ポリエチレンとしては、高圧法低密度ポリエチレン、中密度ポリエチレン、高密度ポリエチレン、直鎖状低密度ポリエチレンなどのエチレンの単独重合体またはエチレンとα−オレフィンとの共重合体；エチレン・酢酸ビニル共重合体などのエチレンと他のビニル系単量体との共重合体等が挙げられる。 Specific examples of the compound represented by the formula (I) include poly-4-methylpentene-1 and a copolymer of poly-4-methylpentene-1, such as poly-4-methylpentene-1. Examples of the polymer copolymerized with vinyl monomers and polyethylene include polyethylene homopolymers such as high-pressure low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene. Or a copolymer of ethylene and an α-olefin; a copolymer of ethylene and another vinyl monomer such as an ethylene / vinyl acetate copolymer;
エチレンと共重合されるα−オレフィンとしては、例えば、プロピレン、１−ブテン、１−ヘキセン、１−オクテンなどが挙げられる。他のビニル系単量体としては、例えば、酢酸ビニル等のビニルエステル；（メタ）アクリル酸、（メタ）アクリル酸メチル、（メタ）アクリル酸エチル、（メタ）アクリル酸ｎ−ブチル等の（メタ）アクリル酸およびそのアルキルエステルなどが挙げられる。 Examples of the α-olefin copolymerized with ethylene include propylene, 1-butene, 1-hexene, 1-octene and the like. Examples of other vinyl monomers include vinyl esters such as vinyl acetate; (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate ( And meth) acrylic acid and alkyl esters thereof.
また、本発明の熱可塑性樹脂は熱可塑性炭素前駆体と容易に溶融混練できるという点から、非晶性の場合、ガラス転移温度が２５０℃以下、結晶性の場合、結晶融点が３００℃以下であることが好ましい。 In addition, the thermoplastic resin of the present invention can be easily melt-kneaded with a thermoplastic carbon precursor, so that when amorphous, the glass transition temperature is 250 ° C. or lower, and when crystalline, the crystalline melting point is 300 ° C. or lower. Preferably there is.
（２）熱可塑性炭素前駆体
本発明に用いられる熱可塑性炭素前駆体は、酸素または酸素／沃素の混合ガス雰囲気下、２００℃以上３５０℃未満で２〜３０時間保持した後、次いで３５０℃以上５００℃未満の温度で５時間保持することで、初期重量の８０ｗｔ％以上が残存する熱可塑性炭素前駆体を用いるのが好ましい。上記条件で、残存量が初期重量の８０％未満であると、熱可塑性炭素前駆体から充分な炭化率で炭素繊維を得ることができず、好ましくない。
(2) Thermoplastic carbon precursor The thermoplastic carbon precursor used in the present invention is maintained at 200 ° C. or higher and lower than 350 ° C. for 2 to 30 hours in an oxygen or oxygen / iodine mixed gas atmosphere, and then 350 ° C. or higher. It is preferable to use a thermoplastic carbon precursor in which 80 wt% or more of the initial weight remains by holding at a temperature of less than 500 ° C. for 5 hours. Under the above conditions, if the residual amount is less than 80% of the initial weight, carbon fibers cannot be obtained with a sufficient carbonization rate from the thermoplastic carbon precursor, which is not preferable.
より好ましくは、上記条件において初期重量の８５％以上が残存することである。上記条件を満たす熱可塑性炭素前駆体としては、具体的にはレーヨン、ピッチ、ポリアクリロニトリル、ポリα−クロロアクリロニトリル、ポリカルボジイミド、ポリイミド、ポリエーテルイミド、ポリベンゾアゾール、およびアラミド類等が挙げられ、これらの中でピッチ、ポリアクリロニトリル、ポリカルボジイミドが好ましく、ピッチがさらに好ましい。 More preferably, 85% or more of the initial weight remains under the above conditions. Specific examples of the thermoplastic carbon precursor that satisfies the above conditions include rayon, pitch, polyacrylonitrile, poly α-chloroacrylonitrile, polycarbodiimide, polyimide, polyetherimide, polybenzoazole, and aramids. Among these, pitch, polyacrylonitrile, and polycarbodiimide are preferable, and pitch is more preferable.
またピッチの中でも一般的に高強度、高弾性率の期待されるメソフェーズピッチが好ましい。なお、メソフェーズピッチとは溶融状態において光学的異方性相（液晶相）を形成しうる化合物を指す。メソフェーズピッチの原料としては石炭や石油の蒸留残渣を使用してもよく、有機化合物を使用しても良いが、安定化や炭素化もしくは黒鉛化のしやすさから、ナフタレン等の芳香族炭化水素を原料としたメソフェーズピッチを用いるのが好ましい。上記熱可塑性炭素前駆体は熱可塑性樹脂１００重量部に対し１〜１５０重量部、好ましくは５〜１００重量部を使用しうる。 Of the pitches, mesophase pitches which are generally expected to have high strength and high elastic modulus are preferred. The mesophase pitch refers to a compound that can form an optically anisotropic phase (liquid crystal phase) in a molten state. As a raw material for mesophase pitch, a distillation residue of coal or petroleum may be used, or an organic compound may be used. However, aromatic hydrocarbons such as naphthalene are used because of their ease of stabilization, carbonization or graphitization. It is preferable to use a mesophase pitch using as a raw material. The thermoplastic carbon precursor may be used in an amount of 1 to 150 parts by weight, preferably 5 to 100 parts by weight, based on 100 parts by weight of the thermoplastic resin.
（３）熱可塑性樹脂と熱可塑性炭素前駆体とからなる混合物の製造
本発明で使用する混合物は、熱可塑性樹脂と熱可塑性炭素前駆体から製造される。本発明で使用する混合物から、繊維径が１μｍ未満である炭素繊維を製造するためには、熱可塑性炭素前駆体の熱可塑性樹脂中への分散径が０．０１〜５０μｍとなるのが好ましい。熱可塑性炭素前駆体の熱可塑性樹脂（Ｉ）中への分散径が０．０１〜５０μｍの範囲を逸脱すると、高性能複合材料用としての炭素繊維を製造することが困難となることがある。熱可塑性炭素前駆体の分散径のより好ましい範囲は０．０１〜３０μｍである。また、熱可塑性樹脂と熱可塑性炭素前駆体からなる混合物を、３００℃で３分保持した後、熱可塑性炭素前駆体の熱可塑性樹脂中への分散径が０．０１〜５０μｍであることが好ましい。
(3) Manufacture of the mixture which consists of a thermoplastic resin and a thermoplastic carbon precursor The mixture used by this invention is manufactured from a thermoplastic resin and a thermoplastic carbon precursor. In order to produce carbon fibers having a fiber diameter of less than 1 μm from the mixture used in the present invention, the dispersion diameter of the thermoplastic carbon precursor in the thermoplastic resin is preferably 0.01 to 50 μm. When the dispersion diameter of the thermoplastic carbon precursor in the thermoplastic resin (I) deviates from the range of 0.01 to 50 μm, it may be difficult to produce carbon fibers for high-performance composite materials. A more preferable range of the dispersion diameter of the thermoplastic carbon precursor is 0.01 to 30 μm. Moreover, it is preferable that the dispersion diameter of the thermoplastic carbon precursor in the thermoplastic resin is 0.01 to 50 μm after holding the mixture of the thermoplastic resin and the thermoplastic carbon precursor at 300 ° C. for 3 minutes. .
一般に、熱可塑性樹脂と熱可塑性炭素前駆体との溶融混練で得た混合物を、溶融状態で保持しておくと時間と共に熱可塑性炭素前駆体が凝集するが、熱可塑性炭素前駆体の凝集により、分散径が５０μｍを超えると、高性能複合材料用としての炭素繊維を製造することが困難となることがある。熱可塑性炭素前駆体の凝集速度の程度は、使用する熱可塑性樹脂と熱可塑性炭素前駆体との種類により変動するが、より好ましくは３００℃で５分以上、さらに好ましくは３００℃で１０分以上、０．０１〜５０μｍの分散径を維持していることが好ましい。なお、混合物中で熱可塑性炭素前駆体は島相を形成し、球状あるいは楕円状となるが、本発明で言う分散径とは混合物中で熱可塑性炭素前駆体の球形の直径または楕円体の長軸径を意味する。 Generally, when a mixture obtained by melt-kneading a thermoplastic resin and a thermoplastic carbon precursor is kept in a molten state, the thermoplastic carbon precursor aggregates with time, but due to the aggregation of the thermoplastic carbon precursor, If the dispersion diameter exceeds 50 μm, it may be difficult to produce carbon fibers for high performance composite materials. The degree of the aggregation rate of the thermoplastic carbon precursor varies depending on the type of the thermoplastic resin and the thermoplastic carbon precursor used, but is more preferably 5 minutes or more at 300 ° C., more preferably 10 minutes or more at 300 ° C. It is preferable to maintain a dispersion diameter of 0.01 to 50 μm. The thermoplastic carbon precursor in the mixture forms an island phase and is spherical or elliptical. The dispersion diameter referred to in the present invention is the spherical diameter of the thermoplastic carbon precursor or the length of the ellipsoid in the mixture. It means the shaft diameter.
熱可塑性炭素前駆体の使用量は、熱可塑性樹脂１００重量部に対して１〜１５０重量部、好ましくは５〜１００重量部である。熱可塑性炭素前駆体の使用量が１５０重量部を超えると所望の分散径を有する熱可塑性炭素前駆体が得られず、１重量部未満であると目的とする炭素繊維を安価に製造する事ができない等の問題が生じるため好ましくない。 The usage-amount of a thermoplastic carbon precursor is 1-150 weight part with respect to 100 weight part of thermoplastic resins, Preferably it is 5-100 weight part. If the amount of the thermoplastic carbon precursor used exceeds 150 parts by weight, a thermoplastic carbon precursor having a desired dispersion diameter cannot be obtained, and if it is less than 1 part by weight, the target carbon fiber can be produced at low cost. This is not preferable because problems such as inability to occur occur.
熱可塑性樹脂と熱可塑性炭素前駆体とから混合物を製造する方法は、溶融状態における混練が好ましい。熱可塑性樹脂と熱可塑性炭素前駆体の溶融混練は公知の方法を必要に応じて用いる事ができ、例えば一軸式溶融混練押出機、二軸式溶融混練押出機、ミキシングロール、バンバリーミキサー等が挙げられる。これらの中で上記熱可塑性炭素前駆体を熱可塑性樹脂に良好にミクロ分散させるという目的から、同方向回転型二軸式溶融混練押出機が好ましく使用される。溶融混練温度としては１００℃〜４００℃で行なうのが好ましい。溶融混練温度が１００℃未満であると、熱可塑性炭素前駆体が溶融状態にならず、熱可塑性樹脂とのミクロ分散が困難であるため好ましくない。一方、４００℃を超える場合、熱可塑性樹脂と熱可塑性炭素前駆体の分解が進行するためいずれも好ましくない。溶融混練温度のより好ましい範囲は１５０℃〜３５０℃である。また、溶融混練の時間としては０．５〜２０分間、好ましくは１〜１５分間である。溶融混練の時間が０．５分間未満の場合、熱可塑性炭素前駆体のミクロ分散が困難であるため好ましくない。一方、２０分間を超える場合、炭素繊維の生産性が著しく低下し好ましくない。 As a method for producing a mixture from a thermoplastic resin and a thermoplastic carbon precursor, kneading in a molten state is preferable. The melt kneading of the thermoplastic resin and the thermoplastic carbon precursor can be carried out by using a known method as required, and examples thereof include a uniaxial melt kneading extruder, a biaxial melt kneading extruder, a mixing roll, a Banbury mixer, and the like. It is done. Among these, a co-rotating twin-screw melt kneading extruder is preferably used for the purpose of satisfactorily microdispersing the thermoplastic carbon precursor in the thermoplastic resin. The melt kneading temperature is preferably 100 to 400 ° C. When the melt kneading temperature is less than 100 ° C., the thermoplastic carbon precursor is not in a molten state, and micro-dispersion with the thermoplastic resin is difficult, which is not preferable. On the other hand, when the temperature exceeds 400 ° C., the decomposition of the thermoplastic resin and the thermoplastic carbon precursor proceeds, which is not preferable. A more preferable range of the melt kneading temperature is 150 ° C to 350 ° C. The melt kneading time is 0.5 to 20 minutes, preferably 1 to 15 minutes. When the melt kneading time is less than 0.5 minutes, it is not preferable because micro dispersion of the thermoplastic carbon precursor is difficult. On the other hand, when it exceeds 20 minutes, the productivity of carbon fibers is remarkably lowered, which is not preferable.
本発明では、熱可塑性樹脂と熱可塑性炭素前駆体から溶融混練により混合物を製造する際に、酸素ガス含有量１０％未満のガス雰囲気下で溶融混練することが好ましい。本発明で使用する熱可塑性炭素前駆体は酸素と反応することで溶融混練時に変性不融化してしまい、熱可塑性樹脂中へのミクロ分散を阻害することがある。このため、不活性ガスを流通させながら溶融混練を行い、できるだけ酸素ガス含有量を低下させることが好ましい。より好ましい溶融混練時の酸素ガス含有量は５％未満、さらには１％未満である。上記の方法を実施することで、炭素繊維からなる不織布を製造するための、熱可塑性樹脂と熱可塑性炭素前駆体との混合物を製造することができる。 In the present invention, when a mixture is produced from a thermoplastic resin and a thermoplastic carbon precursor by melt-kneading, it is preferably melt-kneaded in a gas atmosphere having an oxygen gas content of less than 10%. The thermoplastic carbon precursor used in the present invention reacts with oxygen to be modified and infusible at the time of melt kneading, which may inhibit micro-dispersion in the thermoplastic resin. For this reason, it is preferable to perform melt kneading while circulating an inert gas to reduce the oxygen gas content as much as possible. The oxygen gas content during melt kneading is more preferably less than 5%, and further less than 1%. By implementing said method, the mixture of a thermoplastic resin and a thermoplastic carbon precursor for manufacturing the nonwoven fabric which consists of carbon fibers can be manufactured.
（４）炭素繊維を製造する方法
本発明の炭素繊維は、上述の熱可塑性樹脂と熱可塑性炭素前駆体とからなる混合物から製造することができる。即ち、本発明の炭素繊維は、（４−１）熱可塑性樹脂１００重量部と熱可塑性炭素前駆体１〜１５０重量部からなる混合物から前駆体繊維を形成する工程、（４−２）前駆体繊維を安定化処理に付して前駆体繊維中の熱可塑性炭素前駆体を安定化して安定化前駆体繊維を形成する工程、（４−３）安定化前駆体繊維から熱可塑性樹脂を除去して繊維状炭素前駆体を形成する工程、そして、（４−４）繊維状炭素前駆体を炭素化もしくは黒鉛化する工程を経ることで製造される。各工程について、以下に詳細に説明する。
(4) Method for Producing Carbon Fiber The carbon fiber of the present invention can be produced from a mixture comprising the above-described thermoplastic resin and a thermoplastic carbon precursor. That is, the carbon fiber of the present invention comprises (4-1) a step of forming a precursor fiber from a mixture of 100 parts by weight of a thermoplastic resin and 1 to 150 parts by weight of a thermoplastic carbon precursor, (4-2) a precursor. A step of stabilizing the thermoplastic carbon precursor in the precursor fiber to form a stabilized precursor fiber by subjecting the fiber to a stabilization treatment; (4-3) removing the thermoplastic resin from the stabilized precursor fiber; And a step of forming a fibrous carbon precursor and (4-4) a step of carbonizing or graphitizing the fibrous carbon precursor. Each step will be described in detail below.
（４−１）熱可塑性樹脂と熱可塑性炭素前駆体からなる混合物から前駆体繊維を形成する工程
本発明では、熱可塑性樹脂と熱可塑性炭素前駆体の溶融混練で得た混合物前駆体繊維を形成する。前駆体繊維を製造する方法としては、熱可塑性樹脂と熱可塑性炭素前駆体とからなる混合物を紡糸口金より溶融紡糸することにより得る方法などを例示することができる。溶融紡糸する際の紡糸温度としては１５０℃〜４００℃、好ましくは１８０℃〜３５０℃である。紡糸引取り速度としては１０ｍ／分〜２０００ｍ／分である事が好ましい。また、別法として熱可塑性樹脂と熱可塑性炭素前駆体の溶融混練で得た混合物から、メルトブロー法により前駆体繊維を形成する方法も例示することができる。メルトブローの条件としては、吐出ダイ温度が１５０〜４００℃、ガス温度が１５０〜４００℃の範囲が好適に用いられる。メルトブローの気体噴出速度は、前駆体繊維の繊維径に影響するが、気体噴出速度は、通常２０００〜１００ｍ／ｓであり、より好ましくは１０００〜２００ｍ／ｓである。
(4-1) Step of forming precursor fibers from a mixture comprising a thermoplastic resin and a thermoplastic carbon precursor In the present invention, a mixture precursor fiber obtained by melt-kneading a thermoplastic resin and a thermoplastic carbon precursor is formed. To do. Examples of the method for producing the precursor fiber include a method obtained by melt spinning a mixture of a thermoplastic resin and a thermoplastic carbon precursor from a spinneret. The spinning temperature for melt spinning is 150 ° C to 400 ° C, preferably 180 ° C to 350 ° C. The spinning take-up speed is preferably 10 m / min to 2000 m / min. Moreover, the method of forming precursor fiber by the melt blow method from the mixture obtained by melt-kneading a thermoplastic resin and a thermoplastic carbon precursor as another method can also be illustrated. As the conditions for melt blowing, a range in which the discharge die temperature is 150 to 400 ° C. and the gas temperature is 150 to 400 ° C. is preferably used. The gas blowing speed of the melt blow affects the fiber diameter of the precursor fiber, but the gas blowing speed is usually 2000 to 100 m / s, more preferably 1000 to 200 m / s.
熱可塑性樹脂と熱可塑性炭素前駆体との混合物を溶融混練し、その後ダイより吐出する際、溶融混練した後溶融状態のままで配管内を送液し吐出ダイまで連続的に送液するのが好ましく、溶融混練から紡糸口金吐出までの移送時間は１０分以内である事が好ましい。 When a mixture of a thermoplastic resin and a thermoplastic carbon precursor is melt-kneaded and then discharged from the die, it is melt-kneaded and then fed in the molten state in a molten state and continuously sent to the discharge die. Preferably, the transfer time from melt-kneading to spinneret discharge is preferably within 10 minutes.
（４−２）前駆体繊維を安定化処理に付して前駆体繊維中の熱可塑性炭素前駆体を安定化して安定化前駆体繊維を形成する工程
本発明の製造方法における第二の工程では、上記で作成した前駆体繊維を沃素と酸素との混合ガス雰囲気下で安定化処理に付して前駆体繊維中の熱可塑性炭素前駆体の安定化と熱可塑性樹脂のゲル化を促進させて安定化前駆体繊維を形成する。
(4-2) A step of subjecting the precursor fiber to stabilization treatment to stabilize the thermoplastic carbon precursor in the precursor fiber to form a stabilized precursor fiber In the second step in the production method of the present invention, The precursor fiber prepared above is subjected to a stabilization treatment in a mixed gas atmosphere of iodine and oxygen to promote the stabilization of the thermoplastic carbon precursor in the precursor fiber and the gelation of the thermoplastic resin. Stabilized precursor fibers are formed.
熱可塑性炭素前駆体の安定化は炭素化もしくは黒鉛化された炭素繊維を得るために必要な工程であり、これを実施せず次工程である熱可塑性樹脂の除去を行った場合、熱可塑性炭素前駆体が熱分解したり融着したりするなどの問題が生じる。また、熱可塑性樹脂のゲル化は、熱分解による熱可塑性樹脂の除去時に、熱可塑性樹脂のメルトを抑える効果がある。このため、熱可塑性樹脂除去時に、プレフォームが作成されている場合、その形状を維持できるといった長所を有する。 Stabilization of the thermoplastic carbon precursor is a necessary process for obtaining carbonized or graphitized carbon fibers. If the thermoplastic resin is removed as the next process without carrying out this process, the thermoplastic carbon is removed. Problems such as thermal decomposition and fusion of the precursor occur. The gelation of the thermoplastic resin has an effect of suppressing the melt of the thermoplastic resin when the thermoplastic resin is removed by thermal decomposition. For this reason, when the preform is created at the time of removing the thermoplastic resin, the shape can be maintained.
例えば、メルトブローで前駆体繊維を作成した場合、その形状は一般に不織布状となるが、熱可塑性樹脂のゲル化が著しく低い場合、熱可塑性樹脂を除去する際に熱可塑性樹脂がメルトし、その結果不織布の形態を維持できなくなったり、熱可塑性樹脂のメルトにより、不織布の緻密化が進行したりするといった問題を有する。 For example, when the precursor fiber is prepared by melt blow, the shape is generally a nonwoven fabric, but when the thermoplastic resin is extremely gelled, the thermoplastic resin melts when the thermoplastic resin is removed, and as a result There is a problem that the shape of the nonwoven fabric cannot be maintained, or the densification of the nonwoven fabric proceeds due to the melt of the thermoplastic resin.
本発明では、前駆体繊維中の熱可塑性炭素前駆体の安定化と熱可塑性樹脂のゲル化を促進させるための方法として、沃素と酸素との混合ガス雰囲気下で安定化処理する方法を好適に用いる。沃素と酸素との混合ガスによる不融化は、温度５０〜３５０℃で行なうのが好ましい。温度が５０℃未満で処理した場合、不融化に長時間を有するため好ましくない。また、３５０℃を超える場合、熱可塑性樹脂のメルトを引き起こし、最終的に得られる極細炭素繊維からなる不織布の気孔率が６０％未満となり好ましくない。より好ましくは８０〜３００℃で、５時間以下、好ましくは２時間以下で所望のガス雰囲気中で処理する事が好ましい。 In the present invention, as a method for promoting the stabilization of the thermoplastic carbon precursor in the precursor fiber and the gelation of the thermoplastic resin, a method of performing a stabilization treatment in a mixed gas atmosphere of iodine and oxygen is preferably used. Use. Infusibilization with a mixed gas of iodine and oxygen is preferably performed at a temperature of 50 to 350 ° C. When the treatment is performed at a temperature of less than 50 ° C., it is not preferable because the infusibilization takes a long time. Moreover, when it exceeds 350 degreeC, the melt of a thermoplastic resin is caused and the porosity of the nonwoven fabric which consists of ultrafine carbon fiber finally obtained becomes less than 60%, and is unpreferable. More preferably, the treatment is performed in a desired gas atmosphere at 80 to 300 ° C. for 5 hours or less, preferably 2 hours or less.
本発明では、沃素と酸素の混合ガス雰囲気下における安定化処理により、１００℃の熱デカリンへの溶解量が５０ｗｔ％未満となる安定化前駆体繊維を形成することを最大の特徴とする。１００℃の熱デカリンへの溶解量が５０ｗｔ％以上である安定化前駆体繊維を用いて、次工程である熱可塑性樹脂の除去、炭素化・黒鉛化を行なった場合、前駆体繊維中の熱可塑性炭素前駆体の安定化が不十分であるばかりでなく、熱可塑性樹脂のゲル化も不十分であるため、得られる炭素繊維が融着してしまうだけでなく、プレフォームを作成している場合にはその形状も維持できないといった問題を有する。 The most characteristic feature of the present invention is that a stabilized precursor fiber having a dissolution amount in hot decalin at 100 ° C. of less than 50 wt% is formed by a stabilizing treatment in a mixed gas atmosphere of iodine and oxygen. When the stabilization precursor fiber having a dissolution amount in the thermal decalin at 100 ° C. of 50 wt% or more is used to remove the thermoplastic resin, carbonization / graphitization, which is the next step, the heat in the precursor fiber Not only is the stabilization of the plastic carbon precursor insufficient, but the gelation of the thermoplastic resin is also insufficient, so the resulting carbon fibers are not only fused, but a preform is created. In some cases, the shape cannot be maintained.
融着のない炭素繊維、プレフォームの形状を維持するためには、１００℃の熱デカリンへの溶解量が３０ｗｔ％未満、より好ましくは１０ｗｔ％未満であることが好ましい。 In order to maintain the shape of carbon fiber and preform without fusion, the amount dissolved in hot decalin at 100 ° C. is preferably less than 30 wt%, more preferably less than 10 wt%.
（４−３）安定化前駆体繊維から熱可塑性樹脂を除去して繊維状炭素前駆体を形成する工程
本発明の製造方法における第三の工程は安定化前駆体繊維に含まれる熱可塑性樹脂を熱分解で除去するものであり、具体的には安定化前駆体繊維中に含まれる熱可塑性樹脂を除去し、安定化された繊維状炭素前駆体のみを分離し、繊維状炭素前駆体を形成する。この工程では、繊維状炭素前駆体の熱分解をできるだけ抑え、かつ熱可塑性樹脂を分解除去し、繊維状炭素前駆体のみを分離する必要がある。
(4-3) Step of forming a fibrous carbon precursor by removing the thermoplastic resin from the stabilized precursor fiber The third step in the production method of the present invention is the thermoplastic resin contained in the stabilized precursor fiber. It is removed by pyrolysis. Specifically, the thermoplastic resin contained in the stabilized precursor fiber is removed, and only the stabilized fibrous carbon precursor is separated to form the fibrous carbon precursor. To do. In this step, it is necessary to suppress the thermal decomposition of the fibrous carbon precursor as much as possible, to decompose and remove the thermoplastic resin, and to separate only the fibrous carbon precursor.
熱可塑性樹脂の除去は、酸素存在雰囲気および不活性ガス雰囲気のどちらでもよい。酸素存在雰囲気で熱可塑性樹脂を除去する場合には、３５０℃以上６００℃未満の温度で除去する必要がある。なお、ここで言う酸素存在雰囲気下とは、酸素濃度が１〜１００％のガス雰囲気を指しており、酸素以外に二酸化炭素、窒素、アルゴン等の不活性ガスや、沃素、臭素等の不活性ガスを含有していても良い。これら条件の中でも、特にコストの関係から空気を用いることが特に好ましい。 The removal of the thermoplastic resin may be performed in either an oxygen-existing atmosphere or an inert gas atmosphere. When removing the thermoplastic resin in an oxygen-existing atmosphere, it is necessary to remove it at a temperature of 350 ° C. or higher and lower than 600 ° C. The term “in the presence of oxygen” as used herein refers to a gas atmosphere having an oxygen concentration of 1 to 100%. In addition to oxygen, inert gases such as carbon dioxide, nitrogen, and argon, and inert gases such as iodine and bromine are used. It may contain gas. Among these conditions, it is particularly preferable to use air particularly from the viewpoint of cost.
安定化前駆体繊維に含まれる熱可塑性樹脂を除去する温度が３５０℃未満のときには、繊維状炭素前駆体の熱分解は抑えられるものの、熱可塑性樹脂の熱分解を充分行なうことができず好ましくない。また、６００℃以上であると、熱可塑性樹脂の熱分解は充分行なうことができるものの、繊維状炭素前駆体の熱分解も起こってしまい、結果として熱可塑性炭素前駆体から得られる炭素繊維の炭化収率を低下させてしまい好ましくない。 When the temperature for removing the thermoplastic resin contained in the stabilized precursor fiber is less than 350 ° C., the thermal decomposition of the fibrous carbon precursor can be suppressed, but the thermoplastic resin cannot be sufficiently decomposed, which is not preferable. . If the temperature is 600 ° C. or higher, the thermoplastic resin can be sufficiently thermally decomposed, but the fibrous carbon precursor is also thermally decomposed, resulting in carbonization of the carbon fiber obtained from the thermoplastic carbon precursor. The yield is lowered, which is not preferable.
安定化前駆体繊維に含まれる熱可塑性樹脂を分解する温度としては、酸素雰囲気下３８０〜５００℃であることが好ましく、特に４００〜４５０℃の温度範囲で、０．５〜１０時間処理するのが好ましい。上記処理を施すことで、熱可塑性樹脂は使用した初期重量の１５ｗｔ％以下にまで分解される。また、熱可塑性炭素前駆体は使用した初期重量の８０ｗｔ％以上が繊維状炭素前駆体として残存する。 The temperature at which the thermoplastic resin contained in the stabilized precursor fiber is decomposed is preferably 380 to 500 ° C. in an oxygen atmosphere, particularly in the temperature range of 400 to 450 ° C. for 0.5 to 10 hours. Is preferred. By performing the above treatment, the thermoplastic resin is decomposed to 15 wt% or less of the initial weight used. Moreover, 80 wt% or more of the initial weight used for the thermoplastic carbon precursor remains as a fibrous carbon precursor.
また、不活性ガス雰囲気下で熱可塑性樹脂を除去する場合には、３５０℃以上６００℃未満の温度で除去する必要がある。なお、ここで言う不活性ガス雰囲気下とは、酸素濃度３０ｐｐｍ以下、より好ましくは２０ｐｐｍ以下の二酸化炭素、窒素、アルゴン等のガスをさす。なお、沃素、臭素等のハロゲンガスを含有していても良い。 Moreover, when removing a thermoplastic resin in inert gas atmosphere, it is necessary to remove at the temperature of 350 degreeC or more and less than 600 degreeC. The term “inert gas atmosphere” as used herein refers to a gas such as carbon dioxide, nitrogen, or argon having an oxygen concentration of 30 ppm or less, more preferably 20 ppm or less. Note that a halogen gas such as iodine or bromine may be contained.
なお、本工程で使用する不活性ガスとしては、コストの関係から二酸化炭素と窒素が好ましく用いることができ、窒素が特に好ましい。安定化前駆体繊維からなる不織布に含まれる熱可塑性樹脂を除去する温度が３５０℃未満のとき、繊維状炭素前駆体の熱分解は抑えられるものの、熱可塑性樹脂の熱分解を充分行なうことができず好ましくない。また、６００℃以上であると、熱可塑性樹脂の熱分解は充分行なうことができるものの、繊維状炭素前駆体の熱分解も起こってしまい、結果として熱可塑性炭素前駆体から得られる炭素繊維からなる不織布の炭化収率を低下させてしまい好ましくない。安定化前駆体繊維に含まれる熱可塑性樹脂を分解する温度としては、不活性ガス雰囲気下３８０〜５５０℃とすることが好ましく、特に４００〜５３０℃の温度範囲で、０．５〜１０時間処理するのが好ましい。上記処理を施すことで、使用した熱可塑性樹脂の初期重量の１５ｗｔ％以下にまで分解される。また、使用した熱可塑性炭素前駆体の初期重量の８０ｗｔ％以上が繊維状炭素前駆体として残存する。 In addition, as an inert gas used at this process, a carbon dioxide and nitrogen can be used preferably from the relationship of cost, and nitrogen is especially preferable. When the temperature at which the thermoplastic resin contained in the nonwoven fabric composed of the stabilized precursor fibers is removed is less than 350 ° C., the thermal decomposition of the fibrous carbon precursor can be suppressed, but the thermoplastic resin can be sufficiently decomposed. It is not preferable. Further, when the temperature is 600 ° C. or higher, the thermoplastic resin can be sufficiently thermally decomposed, but the fibrous carbon precursor is also thermally decomposed. As a result, the thermoplastic resin is made of carbon fibers obtained from the thermoplastic carbon precursor. Since the carbonization yield of a nonwoven fabric is reduced, it is not preferable. The temperature for decomposing the thermoplastic resin contained in the stabilized precursor fiber is preferably set to 380 to 550 ° C. in an inert gas atmosphere, particularly in the temperature range of 400 to 530 ° C., for 0.5 to 10 hours. It is preferable to do this. By performing the above-mentioned treatment, it is decomposed to 15 wt% or less of the initial weight of the used thermoplastic resin. Moreover, 80 wt% or more of the initial weight of the used thermoplastic carbon precursor remains as a fibrous carbon precursor.
（４−４）繊維状炭素前駆体からなる不織布を炭素化もしくは黒鉛化する工程
本発明の製造方法における第四の工程は、熱可塑性樹脂を初期重量の１５ｗｔ％以下にまで除いた繊維状炭素前駆体を不活性ガス雰囲気中で炭素化もしくは黒鉛化し炭素繊維を製造するものである。本発明において繊維状炭素前駆体は不活性ガス雰囲気下での高温処理により炭素化もしくは黒鉛化し、所望の炭素繊維となる。得られる炭素繊維の繊維径としては０．００１μｍ〜１μｍであることが好ましい。
(4-4) Step of carbonizing or graphitizing a nonwoven fabric composed of a fibrous carbon precursor The fourth step in the production method of the present invention is fibrous carbon obtained by removing the thermoplastic resin to 15 wt% or less of the initial weight. The precursor is carbonized or graphitized in an inert gas atmosphere to produce a carbon fiber. In the present invention, the fibrous carbon precursor is carbonized or graphitized by high-temperature treatment in an inert gas atmosphere to form a desired carbon fiber. The fiber diameter of the obtained carbon fiber is preferably 0.001 μm to 1 μm.
繊維状炭素前駆体からなる不織布の炭素化もしくは黒鉛化は公知の方法で行なうことができる。使用される不活性ガスとしては窒素、アルゴン等があげられ、温度は５００℃〜３５００℃、好ましくは８００℃〜３０００℃である。なお、炭素化もしくは黒鉛化する際の、酸素濃度は２０ｐｐｍ以下、さらには１０ｐｐｍ以下であることが好ましい。上記の方法を実施することで、炭素繊維を製造することができる。 Carbonization or graphitization of a nonwoven fabric made of a fibrous carbon precursor can be performed by a known method. Examples of the inert gas used include nitrogen and argon, and the temperature is 500 ° C to 3500 ° C, preferably 800 ° C to 3000 ° C. Note that the oxygen concentration during carbonization or graphitization is preferably 20 ppm or less, and more preferably 10 ppm or less. By carrying out the above method, carbon fibers can be produced.
（５）炭素繊維からなる不織布
上述の通りの製造方法を実施することで、繊維径が１μｍ未満である炭素繊維を製造することができる。なお、本発明では上記方法で作成した炭素繊維が不織布の形態であっても良い。なお、本発明で言う不織布とは繊維径０．００１〜２０μｍの繊維が複雑に絡み合ってできた厚み１μｍ〜１０００００μｍの面状形態を指す。
(5) Nonwoven fabric composed of carbon fibers By carrying out the production method as described above, carbon fibers having a fiber diameter of less than 1 μm can be produced. In the present invention, the carbon fiber prepared by the above method may be in the form of a nonwoven fabric. The nonwoven fabric referred to in the present invention refers to a planar form having a thickness of 1 μm to 100,000 μm formed by intricately intertwining fibers having a fiber diameter of 0.001 to 20 μm.
本方法で得られた炭素繊維からなる不織布は、その繊維径が０．００１〜１μｍである炭素繊維から構成される。本方法で得られた炭素繊維からなる不織布は、その炭素繊維同士が複雑に絡み合うことで不織布形態を維持しているが、その形態保持をより強固にするために、炭素繊維間で一部融着が起こっていても良い。 The nonwoven fabric made of carbon fibers obtained by this method is composed of carbon fibers having a fiber diameter of 0.001 to 1 μm. The non-woven fabric made of carbon fibers obtained by this method maintains the non-woven fabric form by intricately intertwining the carbon fibers. Wearing may be happening.
本発明の炭素繊維からなる不織布は、炭素繊維からなる不織布数枚を重ねて、一枚のフェルト状またはマット状にしても良い。また、炭素繊維の製造過程で形成される前駆体繊維からなる不織布、安定化前駆体繊維からなる不織布、繊維状炭素前駆体からなる不織布を複数枚重ねてから各次工程を経ることで、一枚の炭素繊維からなるフェルトまたはマットを製造しても良い。 The nonwoven fabric made of carbon fiber of the present invention may be made into a single felt shape or mat shape by overlapping several nonwoven fabrics made of carbon fiber. In addition, a plurality of nonwoven fabrics made of precursor fibers, stabilized precursor fibers, and nonwoven fabrics made of fibrous carbon precursors, which are formed in the process of manufacturing carbon fibers, are passed through each subsequent process, A felt or mat made of a piece of carbon fiber may be produced.
以下、本発明を実施例により更に具体的に説明するが、本発明はこれにより何等限定を受けることは無い。尚、本発明において、前駆体繊維の繊維径、炭素繊維径は走査電子顕微鏡（株式会社日立製作所製「Ｓ−２４００」）にて測定した。 EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention does not receive any limitation by this. In the present invention, the fiber diameter and carbon fiber diameter of the precursor fiber were measured with a scanning electron microscope (“S-2400” manufactured by Hitachi, Ltd.).
また、不織布の気孔率はマイクロメリテックス社製ポアサイザー９３２０を用い、測定圧力範囲１００ｋＰａ〜２０７ＭＰａ、２７℃の条件で測定した。
不織布の気孔率は、下記式を用いて評価した。
気孔率（Ｐ） ＝ Ｖｐ × Ｗ × １００／Ｖ
なお、Ｖｐは細孔容積（ｃｃ／ｇ）であり、Ｗは不織布の質量、Ｖは試料体積を意味する。なお、水銀の接触角として１３０°表面張力として４８４ｍＮ／ｍを用いた。
Moreover, the porosity of the nonwoven fabric was measured using a pore sizer 9320 manufactured by Micromeritex Corporation under the conditions of a measurement pressure range of 100 kPa to 207 MPa and 27 ° C.
The porosity of the nonwoven fabric was evaluated using the following formula.
Porosity (P) = Vp x W x 100 / V
Note that Vp is the pore volume (cc / g), W is the mass of the nonwoven fabric, and V is the sample volume. In addition, 484 mN / m was used as a 130 ° surface tension as a contact angle of mercury.
［実施例１］
熱可塑性樹脂としてポリ−４−メチルペンテン−１（ＴＰＸ：グレードＲＴ−１８［三井化学株式会社製］）１００重量部と熱可塑性炭素前駆体としてメソフェーズピッチＡＲ−ＨＰ（三菱ガス化学株式会社製）１１．１部とを同方向二軸押出機（株式会社日本製鋼所製ＴＥＸ−３０、バレル温度２９０℃、窒素気流下）で溶融混練して混合物を作成した。この条件で得られた混合物の、熱可塑性炭素前駆体の熱可塑性樹脂中への分散径は０．０５〜２μｍであった。また、この混合物を３００℃で１０分間保持したが、熱可塑性炭素前駆体の凝集は認められず、分散径は０．０５〜２μｍであった。
[Example 1]
100 parts by weight of poly-4-methylpentene-1 (TPX: grade RT-18 [manufactured by Mitsui Chemicals, Inc.) as a thermoplastic resin and mesophase pitch AR-HP (manufactured by Mitsubishi Gas Chemical Co., Ltd.) as a thermoplastic carbon precursor 11.1 parts was melt-kneaded with the same direction twin screw extruder (TEX-30 manufactured by Nippon Steel Works, barrel temperature 290 ° C., under nitrogen stream) to prepare a mixture. The dispersion diameter of the mixture obtained under these conditions into the thermoplastic resin of the thermoplastic carbon precursor was 0.05 to 2 μm. Further, this mixture was held at 300 ° C. for 10 minutes, but aggregation of the thermoplastic carbon precursor was not observed, and the dispersion diameter was 0.05 to 2 μm.
次いで、上記混合物をメルトブロー法により不織布としたが、その際には、３３０℃で吐出孔より吐出し、吐出孔直下で３５０℃、５００ｍ／分の空気を溶融状態にある繊維に吹き付けることで、繊維径０．５〜５μｍの前駆体繊維からなる不織布を作成した。 Next, the mixture was made into a non-woven fabric by the melt blow method, but in that case, it was discharged from the discharge hole at 330 ° C., and the air just below the discharge hole was blown at 350 ° C. and 500 m / min of air to the molten fiber, A nonwoven fabric composed of precursor fibers having a fiber diameter of 0.5 to 5 μm was prepared.
この前駆体繊維からなる不織布１０重量部に対して０．５重量部の沃素とが含有されるように、空気とともに１リットル容積の耐圧ガラス内に仕込み、１８０℃で４８時間保持して安定化処理を施すことで、安定化前駆体繊維からなる不織布を作成した。この安定化前駆体繊維からなる不織布１重量部を、１００℃の熱デカリン３００ｍｌに２時間浸漬させた後、ろ過した。ろ紙上に残った安定化前駆体繊維の重量は０．９７部であり、溶解量は３ｗｔ％であった。 Stabilize with air in 1 liter pressure glass so that 0.5 parts by weight of iodine is contained in 10 parts by weight of the nonwoven fabric made of this precursor fiber and hold at 180 ° C. for 48 hours. The nonwoven fabric which consists of a stabilization precursor fiber was created by processing. 1 part by weight of the nonwoven fabric composed of the stabilized precursor fiber was immersed in 300 ml of hot decalin at 100 ° C. for 2 hours and then filtered. The weight of the stabilized precursor fiber remaining on the filter paper was 0.97 part, and the dissolution amount was 3 wt%.
次に、安定化前駆体繊維からなる不織布を窒素ガス雰囲気下、昇温速度５℃／分で５５０℃まで昇温することで熱可塑性樹脂を除去して繊維状炭素前駆体からなる不織布を作成した。この繊維状炭素前駆体からなる不織布をアルゴンガス雰囲気下、室温から２８００℃まで３時間で昇温することで炭素繊維からなる不織布を作成した。得られた不織布の炭素繊維径は、１００〜６００ｎｍ前後であった。得られた不織布は緻密化することなく、しなやかさを有していた。なお、不織布の厚みは約１００μｍであり、気孔率は９３％であった。 Next, the nonwoven fabric made of the fibrous precursor is made by removing the thermoplastic resin by heating the nonwoven fabric made of the stabilized precursor fiber to 550 ° C. at a temperature rising rate of 5 ° C./min in a nitrogen gas atmosphere. did. The nonwoven fabric made of carbon fiber was made by heating the nonwoven fabric made of the fibrous carbon precursor from room temperature to 2800 ° C. in an argon gas atmosphere in 3 hours. The carbon fiber diameter of the obtained nonwoven fabric was around 100 to 600 nm. The obtained non-woven fabric was flexible without being densified. The nonwoven fabric had a thickness of about 100 μm and a porosity of 93%.
［比較例１］
熱可塑性樹脂としてポリ−４−メチルペンテン−１（ＴＰＸ：グレードＲＴ−１８［三井化学株式会社製］）１００重量部と熱可塑性炭素前駆体としてメソフェーズピッチＡＲ−ＨＰ（三菱ガス化学株式会社製）１１．１部を同方向二軸押出機（株式会社日本製鋼所製ＴＥＸ−３０、バレル温度２９０℃、窒素気流下）で溶融混練して混合物を作成した。この条件で得られた混合物の、熱可塑性炭素前駆体の熱可塑性樹脂中への分散径は０．０５〜２μｍであった。また、この混合物を３００℃で１０分間保持したが、熱可塑性炭素前駆体の凝集は認められず、分散径は０．０５〜２μｍであった。
[Comparative Example 1]
100 parts by weight of poly-4-methylpentene-1 (TPX: grade RT-18 [manufactured by Mitsui Chemicals, Inc.) as a thermoplastic resin and mesophase pitch AR-HP (manufactured by Mitsubishi Gas Chemical Co., Ltd.) as a thermoplastic carbon precursor 11.1 parts were melt-kneaded with the same direction twin screw extruder (TEX-30, manufactured by Nippon Steel Works, barrel temperature 290 ° C., under nitrogen stream) to prepare a mixture. The dispersion diameter of the mixture obtained under these conditions into the thermoplastic resin of the thermoplastic carbon precursor was 0.05 to 2 μm. Further, this mixture was held at 300 ° C. for 10 minutes, but aggregation of the thermoplastic carbon precursor was not observed, and the dispersion diameter was 0.05 to 2 μm.
次いで、上記混合物をメルトブロー法により不織布としたが、その際には、３３０℃で吐出孔より吐出し、吐出孔直下で３５０℃、５００ｍ／分の空気を溶融状態にある繊維に吹き付けることで、繊維径０．５〜５μｍの前駆体繊維からなる不織布を作成した。
前駆体繊維からなる不織布１０重量部に対して０．５重量部の沃素とが含有されるように、空気とともに１リットル容積の耐圧ガラス内に仕込み、１８０℃で２時間保持して安定化処理を施すことで、安定化前駆体繊維からなる不織布を作成した。この安定化前駆体繊維からなる不織布１重量部を、１００℃の熱デカリン３００ｍｌに２時間浸漬させた後、ろ過した。ろ紙上に残った安定化前駆体繊維の重量は２５重量部であり、溶解量は７５ｗｔ％であった。
Next, the mixture was made into a non-woven fabric by the melt blow method, but in that case, it was discharged from the discharge hole at 330 ° C., and the air just below the discharge hole was blown at 350 ° C. and 500 m / min of air to the molten fiber, A nonwoven fabric composed of precursor fibers having a fiber diameter of 0.5 to 5 μm was prepared.
Stabilize by charging in a 1 liter pressure glass with air so that 0.5 parts by weight of iodine is contained per 10 parts by weight of the nonwoven fabric composed of precursor fibers, and keeping at 180 ° C. for 2 hours. The nonwoven fabric which consists of a stabilization precursor fiber was created. 1 part by weight of the nonwoven fabric composed of the stabilized precursor fiber was immersed in 300 ml of hot decalin at 100 ° C. for 2 hours and then filtered. The weight of the stabilized precursor fiber remaining on the filter paper was 25 parts by weight, and the dissolution amount was 75 wt%.
次に、安定化前駆体繊維からなる不織布を窒素ガス雰囲気下、昇温速度５℃／分で５５０℃まで昇温することで熱可塑性樹脂を除去して繊維状炭素前駆体からなる不織布を作成した。この繊維状炭素前駆体からなる不織布をアルゴンガス雰囲気下、室温から２８００℃まで３時間で昇温することで炭素繊維からなる不織布を作成した。得られた不織布の炭素繊維径は、１００〜６００ｎｍ前後であったが、所々に炭素繊維同士の融着が認められ、不織布は緻密化しており、しなやかさは認められなかった。なお、不織布の厚みは約３０μｍであり、気孔率は３０％であった。 Next, the nonwoven fabric made of the fibrous precursor is made by removing the thermoplastic resin by heating the nonwoven fabric made of the stabilized precursor fiber to 550 ° C. at a temperature rising rate of 5 ° C./min in a nitrogen gas atmosphere. did. The nonwoven fabric made of carbon fiber was made by heating the nonwoven fabric made of the fibrous carbon precursor from room temperature to 2800 ° C. in an argon gas atmosphere in 3 hours. The carbon fiber diameter of the obtained non-woven fabric was around 100 to 600 nm, but fusion of carbon fibers was observed in some places, the non-woven fabric was densified, and no flexibility was recognized. The nonwoven fabric had a thickness of about 30 μm and a porosity of 30%.
Claims (9)
（２）前駆体繊維を、沃素と酸素との混合ガス雰囲気下で安定化処理に付して、１００℃の熱デカリンへの溶解量が５０ｗｔ％未満である安定化前駆体繊維を形成する工程、
（３）安定化前駆体繊維から熱可塑性樹脂を除去して繊維状炭素前駆体を形成する工程、
（４）繊維状炭素前駆体を炭素化もしくは黒鉛化する工程、
を経る、炭素繊維の製造方法。 (1) Precursor from a mixture comprising 1 to 150 parts by weight of a thermoplastic resin and 100 parts by weight of a thermoplastic resin and at least one thermoplastic carbon precursor selected from the group consisting of pitch, polyacrylonitrile, polycarbodiimide, polyimide, polybenzoazole and aramid Forming a body fiber,
(2) A step of subjecting the precursor fiber to a stabilization treatment in a mixed gas atmosphere of iodine and oxygen to form a stabilized precursor fiber having a dissolution amount in hot decalin at 100 ° C. of less than 50 wt%. ,
(3) a step of removing the thermoplastic resin from the stabilized precursor fiber to form a fibrous carbon precursor;
(4) a step of carbonizing or graphitizing the fibrous carbon precursor,
The manufacturing method of carbon fiber which goes through.
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