JP2011117105A - Method for producing rigid heterocyclic polymer fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a rigid heterocyclic polymer fiber improved with fibrous physical properties and spinning stability. <P>SOLUTION: This method for producing the rigid heterocyclic polymer fiber is characterized by satisfying the following conditions (1) to (3): (1) a dope is extruded from a spinneret installed at a spinneret holder controlled in the temperature range from 150 to 250°C; (2) the air gap length from a spinneret outlet to a coagulation bath is ≥1.0 cm; and (3) the spinning is performed at the air gap part by keeping only the range from a spinneret outlet surface to 3.5 cm in its lower direction warmly at 30 to 250°C, or in the case that the air gap length is <3.5 cm, keeping the whole of the air gap part warmly at 30 to 250°C. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing a rigid heterocyclic polymer fiber.

  In spinning fibers made of rigid heterocyclic polymers such as polybenzoxazole and polybenzthiazole, the resulting lyotropic liquid crystal is obtained by using polyphosphoric acid as a solvent because these polymers do not exhibit thermoplasticity. This is a method in which a coherent dope is extruded from a spinneret, stretched by an air gap, diluted with a solvent, and solidified by contact with a non-solvent that does not dissolve the polymer. The lyotropic liquid crystalline dope used here has a problem that the dope is likely to be broken, that is, the spinning stability is lacking, because the viscosity of the dope is high due to the rigidity of the dissolved polymer. Patent Documents 1 and 2 attempt to improve the spinning stability by means of a dope liquid feeding method and a spinneret shape, but require a special spinneret and equipment, and are simpler and easier to manufacture. A method was sought.

JP-A-7-157918 JP 2003-128795 A

  The present invention provides a method for producing a rigid heterocyclic polymer fiber with improved fiber properties and spinning stability.

  As a result of intensive studies in view of the above-mentioned problems, the present inventors have identified a portion of a holder (hereinafter sometimes referred to as a spinneret holder) provided in a spinneret and an air gap in the production of a rigid heterocyclic polymer fiber. By setting the temperature conditions, it was found that the spinning stability was specifically improved and a rigid heterocyclic polymer fiber having good mechanical properties was obtained, and the present invention was completed. That is, the present invention has the following configuration.

（ｎは１〜４の整数であり、ＸはＯ、ＳまたはＮＨであり、Ａｒ^１は炭素数４〜２０の４価の芳香族基であり、そしてＡｒ^２は炭素数４〜２０からなりそして（ｎ＋２）価の芳香族基である）
のそれぞれで表わされる繰返し単位よりなる群から選ばれる少なくとも１種の第１繰返し単位、および、
下記式（Ｃ）および（Ｄ）

（ＸはＯ、ＳまたはＮＨであり、Ａｒ^３は炭素数４〜２０の４価の芳香族基であり、Ｙ^１およびＹ^２はＮまたはＣＨである、但しＹ^１およびＹ^２の少なくともいずれか一方はＮであるものとする）、
のそれぞれで表わされる繰返し単位よりなる群から選ばれる少なくとも１種の第２繰返し単位からなる剛直系複素環高分子をポリリン酸に溶解した紡糸用ドープから繊維を製造する方法において、下記（１）〜（３）の条件を満たすことを特徴とする剛直系複素環高分子繊維の製造方法。
（１）１５０〜２５０℃の温度範囲に制御された紡糸口金ホルダーに設置された紡糸口金より上記ドープを押し出し、
（２）紡糸口金出口〜凝固浴までのエアギャップ長が１．０ｃｍ以上であり、
（３）該エアギャップ部分において、紡糸口金出口面からその下方３．５ｃｍまでの範囲だけを３０〜２５０℃の温度で保温、またはエアギャップ長が３．５ｃｍ未満の場合はエアギャップ部分全体を３０〜２５０℃の温度で保温して紡糸を行う。 1. The following formulas (A) and (B)

(N is an integer of 1 to 4, X is O, S or NH, Ar ¹ is a tetravalent aromatic group having 4 to 20 carbon atoms, and Ar ² is composed of 4 to 20 carbon atoms. And (n + 2) valent aromatic group)
And at least one first repeating unit selected from the group consisting of repeating units each represented by:
Formulas (C) and (D) below

(X is O, S or NH, Ar ³ is a tetravalent aromatic group having 4 to 20 carbon atoms, and Y ¹ and Y ² are N or CH, provided that at least one of Y ¹ and Y ² Either one is N),
In a method for producing a fiber from a spinning dope in which a rigid heterocyclic polymer composed of at least one second repeating unit selected from the group consisting of repeating units represented by each of the above is dissolved in polyphosphoric acid, the following (1) A method for producing a rigid heterocyclic polymer fiber, which satisfies the conditions (3) to (3).
(1) Extruding the dope from a spinneret installed in a spinneret holder controlled to a temperature range of 150 to 250 ° C.,
(2) The air gap length from the spinneret outlet to the coagulation bath is 1.0 cm or more,
(3) In the air gap portion, only the range from the spinneret outlet surface to the lower 3.5 cm is kept at a temperature of 30 to 250 ° C., or if the air gap length is less than 3.5 cm, the entire air gap portion Spinning is carried out at a temperature of 30 to 250 ° C.

2. The rigid heterocyclic polymer described in the above item 1 is represented by the following formula (i):
0.1 ≦ (a + b) / (c + d) ≦ 10 (i)
(A, b, c and d are the number of moles of each repeating unit represented by the above formulas (A), (B), (C) and (D), respectively)
And the specific viscosity measured at 25 ° C. of a solution dissolved in methanesulfonic acid at a concentration of 2.5 mg / 8 mL is 10.0 dL / g or more.

3. 3. The production method according to 1 or 2 above, wherein the maximum draft ratio (MDR) during spinning is 18.5 or more.

  According to the present invention, a rigid heterocyclic polymer fiber having good mechanical properties can be produced with excellent spinning stability without using a special spinneret or apparatus.

  The present invention is represented by at least one first repeating unit selected from the group consisting of repeating units represented by the above formulas (A) and (B), and each of the above formulas (C) and (D). This is a method for producing a rigid heterocyclic polymer fiber comprising at least one second repeating unit selected from the group consisting of repeating units.

を好ましいものとして挙げることができる。 Ar ¹ in the above formulas (A) and (B) or Ar ³ in the above formulas (C) and (D) is a tetravalent aromatic group having 4 to 20 carbon atoms, and both Ar ¹ and Ar ³ are 1 to 2 May contain one ring member nitrogen atom. Ar ¹ and Ar ³ are, for example,

Can be mentioned as preferred.

で表される基として例えば、

（ｎは上記式（Ａ）及び（Ｂ）におけるものと同じ１〜４の整数であり、ｎ_１は１〜３の整数であり、ｎ_２およびｎ_３は０〜４の整数である、但しｎ_２＋ｎ_３は１〜４であるものとする）
で表わされる基を好ましいものとして挙げることができる。 Ar ² has 4 to 20 carbon atoms and is an (n + 2) -valent aromatic group (where n is defined in the above formulas (A) and (B)). The following part containing Ar ² in the above formulas (A) and (B)

As a group represented by

(N is the same integer of 1 to 4 as in the above formulas (A) and (B), n ₁ is an integer of ₁ to 3, and n ₂ and n ₃ are integers of 0 to 4, provided that n ₂ + n ₃ is assumed to be 1 to 4)
The group represented by can be mentioned as a preferable thing.

  In the above formulas (A) and (B), X is O, S or NH, among which O or S is preferable, n is an integer of 1 to 4, and n = 2 is preferable.

（Ｘの定義は上記式（Ａ）及び（Ｂ）に同じであり、Ｚ^１およびＺ^２はそれぞれ独立に、ＮまたはＣＨである。）
及び下記式（Ｂ−１）

（Ｘの定義は上記式（Ａ）及び（Ｂ）に同じであり、Ｚ^１およびＺ^２はそれぞれ独立に、ＮまたはＣＨである）
のそれぞれで表わされる繰返し単位よりなる群から選ばれる少なくとも１種が好ましい。 As said 1st repeating unit, following formula (A-1)

(The definition of X is the same as in the above formulas (A) and (B), and Z ¹ and Z ² are each independently N or CH.)
And the following formula (B-1)

(The definition of X is the same as in the above formulas (A) and (B), and Z ¹ and Z ² are each independently N or CH).
At least one selected from the group consisting of repeating units represented by

In the above formula (C) and (D), Ar ³ is a tetravalent aromatic group having 4 to 20 carbon atoms. As Ar ³ , the same groups as those already exemplified for Ar ¹ can be mentioned as preferred.

の基は

のいずれかである。 In the above formulas (C) and (D), X is O, S or NH, and among these, O and S are preferred, and Y ¹ and Y ² are N or CH, but Y ¹ and Y ² Either one is N. That is, the following including Y ¹ and Y ² in the above formulas (C) and (D)

The basis of

One of them.

（Ｘ、Ｙ^１およびＹ^２の定義は上記式（Ｃ）及び（Ｄ）に同じであり、Ｚ^１およびＺ^２の定義は上記式（Ａ−１）に同じである。）
および下記式（Ｄ−１）

（Ｘ、Ｙ^１およびＹ^２の定義は上記式（Ｃ）及び（Ｄ）に同じであり、Ｚ^１およびＺ^２の定義は上記式（Ｂ−１）に同じである。）
のそれぞれで表わされる繰返し単位よりなる群から選ばれる少なくとも１種が好ましい。 As said 2nd repeating unit, following formula (C-1)

(The definitions of X, Y ¹ and Y ² are the same as in the above formulas (C) and (D), and the definitions of Z ¹ and Z ² are the same as in the above formula (A-1).)
And the following formula (D-1)

(The definitions of X, Y ¹ and Y ² are the same as in the above formulas (C) and (D), and the definitions of Z ¹ and Z ² are the same as in the above formula (B-1).)
At least one selected from the group consisting of repeating units represented by

The rigid heterocyclic polymer in the production method of the present invention comprises a combination of the first repeating unit represented by the above formula (A-1) and the second repeating unit represented by the above formula (C-1), Or what consists of a combination of the 1st repeating unit represented by the said Formula (B-1) and the 2nd repeating unit represented by the said Formula (D-1) is preferable, and a 1st repeating unit and a 2nd repeating unit are shown below. What contains a ratio which satisfies Formula (i) is especially preferable.
0.1 ≦ (a + b) / (c + d) ≦ 10 (i)
(In the above formula (i), a, b, c and d are the number of moles of each repeating unit represented by the above formula (A), (B), (C) and (D), respectively)
More preferably, the ratio of the first repeating unit and the second repeating unit satisfies the following formula (i-1).
0.1 ≦ (a + b) / (c + d) ≦ 1 (i−1)
(In the above formula (i-1), the definitions of a, b, c and d are the same as in the above formula (i).)

  The rigid heterocyclic polymer in the production method of the present invention preferably has a specific viscosity of 10.0 dL / g or more measured at 25 ° C. in a solution in which methanesulfonic acid is dissolved at a concentration of 2.5 mg / 8 mL. If the specific viscosity of the rigid heterocyclic polymer is lower than 10.0 dL / g, the resulting fiber does not exhibit sufficient strength to withstand practical use, which is not preferable. The more preferable range of the specific viscosity of the rigid heterocyclic polymer in the present invention is 10.0 to 50.0 dL / g, and when the specific viscosity of the rigid heterocyclic polymer is higher than 50.0 dL / g, the dope viscosity In the polycondensation process, it is impossible to produce a uniform dope, and even in the spinning process, it is impossible to push out from the spinneret, and a single yarn breakage occurs and the spinning process. Undesirably, the unevenness of fineness between the single yarns becomes remarkable, and the dope cannot be sufficiently stretched to the desired fineness. The specific viscosity of the rigid heterocyclic polymer is preferably 12 to 40 dL / g, more preferably 15 to 35 dL / g.

および下記式（Ｆ）

（Ａｒ^４は炭素数４〜２０の４価の芳香族基である）
のそれぞれで表わされる繰返し単位よりなる群から選ばれる少なくとも１種の第３繰返し単位を、さらに含有することができる。Ａｒ^４は炭素数４〜２０の４価の芳香族基であり、その例としては、Ａｒ^１について既に記載した具体例と同じ基を挙げることができる。第３繰返し単位は、第１繰返し単位、第２繰返し単位および第３繰返し単位の総和を基準にして、好ましくは３０モル％以下、より好ましくは１０モル％以下で用いられる。 The rigid heterocyclic polymer in the present invention is optionally represented by the following formula (E):

And the following formula (F)

(Ar ⁴ is a tetravalent aromatic group having 4 to 20 carbon atoms)
Further, at least one third repeating unit selected from the group consisting of repeating units represented by each of the above can be further contained. Ar ⁴ is a tetravalent aromatic group having 4 to 20 carbon atoms, and examples thereof include the same groups as the specific examples already described for Ar ¹ . The third repeating unit is preferably used in an amount of 30 mol% or less, more preferably 10 mol% or less, based on the sum of the first repeating unit, the second repeating unit, and the third repeating unit.

（上記式（Ｇ）及び（Ｈ）において、ＸおよびＡｒ^１の定義は上記式（Ａ）及び（Ｂ）における定義と同じである。）
のそれぞれで表わされる芳香族アミンおよびその強酸塩よりなる群から選ばれる少なくとも１種の第１原料と、下記式（Ｉ）

（上記式（Ｉ）において、Ａｒ^２およびｎの定義は上記式（Ａ）及び（Ｂ）に同じでありそしてＬはＯＨ、ハロゲン原子またはＯＲで表わされる基であり、Ｒは炭素数６〜２０の１価の芳香族基である）
で表わされる第１芳香族ジカルボン酸類よりなる群から選ばれる少なくとも１種の第２原料、および下記式（Ｊ）

（上記式（Ｊ）において、Ｌの定義は上記式（Ｉ）に同じであり、Ｙ^１およびＹ^２の定義は上記式（Ｃ）及び（Ｄ）に同じである）
で表わされる第２芳香族ジカルボン酸類よりなる群から選ばれる少なくとも１種の第３原料とを重縮合せしめることによって製造される。 Next, the rigid heterocyclic polymer in the present invention has the following formulas (G) and (H):

(In the above formulas (G) and (H), the definitions of X and Ar ¹ are the same as the definitions in the above formulas (A) and (B).)
And at least one first raw material selected from the group consisting of aromatic amines and strong acid salts thereof, and the following formula (I)

(In the above formula (I), the definitions of Ar ² and n are the same as in the above formulas (A) and (B) and L is a group represented by OH, a halogen atom or OR, and R is a group having 6 to 6 carbon atoms. 20 monovalent aromatic groups)
And at least one second raw material selected from the group consisting of first aromatic dicarboxylic acids represented by the formula (J):

(In the above formula (J), the definition of L is the same as that of the above formula (I), and the definitions of Y ¹ and Y ² are the same as those of the above formulas (C) and (D)).
Is produced by polycondensation with at least one third raw material selected from the group consisting of the second aromatic dicarboxylic acids represented by the formula:

（上記式（Ｇ−１）において、Ｚ^１およびＺ^２の定義は上記式（Ａ−１）に同じである）
及び下記式（Ｇ−２）

（上記式（Ｇ−２）において、Ｚ^１およびＺ^２の定義は上記式（Ａ−１）に同じである）
のそれぞれで表わされる化合物およびこれらの化合物の強酸塩よりなる群から選ばれる少なくとも１種または、下記式（Ｈ−１）

（上記式（Ｈ−１）において、Ｚ^１およびＺ^２の定義は上記式（Ｂ−１）に同じである）
及び下記式（Ｈ−２）

（上記式（Ｈ−２）において、Ｚ^１およびＺ^２の定義は上記式（Ｂ−１）に同じである）
のそれぞれで表わされる化合物およびこれらの化合物の強酸塩よりなる群から選ばれる少なくとも１種が好ましい。 As a 1st raw material, following formula (G-1)

(In the above formula (G-1), the definitions of Z ¹ and Z ² are the same as in the above formula (A-1)).
And the following formula (G-2)

(In the above formula (G-2), the definitions of Z ¹ and Z ² are the same as in the above formula (A-1))
Or at least one selected from the group consisting of strong acid salts of these compounds, or the following formula (H-1)

(In the above formula (H-1), the definitions of Z ¹ and Z ² are the same as in the above formula (B-1))
And the following formula (H-2)

(In the above formula (H-2), the definitions of Z ¹ and Z ² are the same as in the above formula (B-1))
And at least one selected from the group consisting of compounds represented by each of these and strong acid salts of these compounds.

The strong acid in the strong acid salt of the compound represented by the above formula (G), (H), (G-1), (G-2), (H-1), (H-2) is hydrochloric acid, One or more kinds selected from inorganic acids such as sulfuric acid and phosphoric acid, or organic acids such as methanesulfonic acid and p-toluenesulfonic acid, with hydrochloric acid being particularly preferred.
In the formula (I), the definitions of Ar ² and n are the same as those in the formulas (A) and (B). In the formula (J), the definitions of Y ¹ and Y ² are the formulas (C) and ( Same as D).

  In the above formulas (I) and (J), L is each independently OH, a halogen atom or OR, where R is a monovalent aromatic group having 6 to 20 carbon atoms. As said halogen atom, a chlorine atom, a bromine atom, etc. can be mentioned, for example. Examples of the monovalent aromatic group having 6 to 20 carbon atoms as R include a phenyl group, a naphthyl group, a biphenyl group, a 4- (2-phenylpropyl) phenyl group, a phenoxyphenyl group, a phenylthiophenyl group, A phenylsulfonylphenyl group, a benzoylphenyl group, etc. can be mentioned. In these aromatic groups, one or more of the hydrogen atoms are each independently a halogen group such as fluorine, chlorine or bromine; an alkyl having 1 to 6 carbon atoms such as a methyl group, an ethyl group, a propyl group or a hexyl group. A cycloalkyl group having 5 to 10 carbon atoms such as a cyclopentyl group and a cyclohexyl group; and an alkoxycarbonyl group such as a methoxycarbonyl group and an ethoxycarbonyl group.

（上記式（Ｉ−１）において、Ｌの定義は上記式（Ｉ）に同じであり、ｎの定義は上記式（Ａ）及び（Ｂ）に同じである。）
で表わされる第１ベンゼンジカルボン酸類が好ましく、Ｌが塩素原子でありｎ＝２のものが特に好ましい。 As said 2nd raw material, following formula (I-1)

(In the above formula (I-1), the definition of L is the same as in the above formula (I), and the definition of n is the same as in the above formulas (A) and (B).)
The first benzenedicarboxylic acids represented by the formula (1) are preferred, and those in which L is a chlorine atom and n = 2 are particularly preferred.

（上記式（Ｊ−１）において、Ｌの定義は上記式（Ｉ）に同じである）
で表わされる第２芳香族ジカルボン酸類が好ましく、Ｌが塩素原子のものが特に好ましい。 Moreover, as a 3rd raw material, following formula (J-1)

(In the above formula (J-1), the definition of L is the same as in the above formula (I))
Are preferred, and those in which L is a chlorine atom are particularly preferred.

The first, second and third raw materials are represented by the following formulas (ii) and (iii)
0.8 ≦ (g + h) / (i + j) ≦ 1.2 (ii)
0.1 ≦ i / j ≦ 10 (iii)
(In the above formulas (ii) and (iii), g, h, i and j are the first and second raw materials represented by the above formulas (G), (H), (I) and (J), respectively) And the number of moles of the third raw material.)
Is preferably used at a rate that satisfies the above, and more preferably when used at a rate that also satisfies the following formula (iii-1).
0.1 ≦ i / j ≦ 1 (iii-1)
(In the above formula (iii-1), the definitions of i and j are the same as in the above formula (iii).)
It is preferable to satisfy

  The first raw material, the second raw material and the third raw material may be mixed as they are in the above ratio and subjected to a polycondensation reaction for obtaining a rigid heterocyclic polymer, or the first raw material and the second raw material, A salt of the first raw material and the third raw material, or a combination of both can be formed in advance and used in the polycondensation reaction.

  The polycondensation reaction for obtaining the rigid heterocyclic polymer in the present invention can be carried out by either a solution reaction performed in a solvent or a solvent-free heating and melting reaction. Especially, it is preferable to make it heat-react with stirring in the reaction solvent. The reaction temperature is preferably 50 to 500 ° C, more preferably 70 to 350 ° C. This is because if the temperature is lower than 50 ° C., the reaction hardly proceeds, and if the temperature is higher than 500 ° C., side reactions such as decomposition tend to occur. Although the reaction time depends on temperature conditions, it is usually 1 hour to several tens of hours. The reaction can be carried out under an inert gas atmosphere such as nitrogen, under pressure or under reduced pressure.

  The polycondensation reaction proceeds even without a catalyst, but a transesterification catalyst may be used if necessary, such as when the aromatic dicarboxylic acid of the above formula (I) or (J) as a raw material is an ester compound. . Examples of the transesterification catalyst include antimony compounds such as antimony trioxide, stannous acetate, tin (II) chloride, tin octylate, dibutyltin oxide, tin compounds such as dibutyltin diacetate, and alkaline earths such as calcium acetate. Examples thereof include metal salts, alkali metal salts such as sodium carbonate and potassium carbonate, and phosphorous acid such as diphenyl phosphite and triphenyl phosphite.

Preferred solvents used in the above polycondensation reaction include, for example, 1-methyl-2-pyrrolidone, 1-cyclohexyl-2-pyrrolidone, dimethylacetamide, dimethyl sulfoxide, diphenyl ether, diphenyl sulfone, dichloromethane, chloroform, tetrahydrofuran, o-cresol, Examples thereof include m-cresol, p-cresol, phosphoric acid, polyphosphoric acid, and the like. Among these, polyphosphoric acid is preferably used. The polymer concentration in the polycondensation dope is preferably 5 to 25% by weight, more preferably 10 to 20% by weight. Further, when using polyphosphoric acid as polycondensation solvent, in particular, the content of P ₂ O ₅ polyphosphoric acid is preferably from 80 to 84 wt%.

  Any apparatus can be used as the apparatus for the polycondensation reaction. In order to reduce temperature unevenness and polycondensation degree unevenness at various parts of the dope, to improve the polycondensation reaction rate, and to reduce foreign matters derived from insoluble components in the dope, a polycondensation reaction apparatus is preferably a biaxial kneader or A kneader, a multi-axis planetary kneader or the like is used.

  In order to prevent decomposition and coloring of the rigid heterocyclic polymer obtained by the above polycondensation reaction, the reaction is desirably performed in a dry inert gas atmosphere. The polymer of the present invention can be variously modified by adding various secondary additives as necessary. Examples of secondary additives include stabilizers, antioxidants, UV absorbers, pigments, colorants, various fillers, electrostatic agents, mold release agents, plasticizers, fragrances, antibacterial and antifungal agents, nucleation And other similar agents such as agents, lubricants, flame retardants, foaming agents, fillers and the like.

  Polyphosphoric acid is used as a solvent for producing a dope for spinning in the production method of the present invention. When polyphosphoric acid is used as the polycondensation solvent, the dope obtained by the polycondensation reaction can be used for spinning as it is. Further, when the dope viscosity after polycondensation is not suitable for spinning, the viscosity can be adjusted by adding polyphosphoric acid to the polycondensation dope for viscosity adjustment. In addition, when a solvent other than polyphosphoric acid is used as a polycondensation solvent in the polycondensation reaction, the dope obtained by the polycondensation reaction is brought into contact with a poor solvent of the produced polymer such as water to form a rigid heterocyclic polymer. A dope for spinning can also be produced by reprecipitation and separation, and re-dissolution in polyphosphoric acid.

  In the case of adjusting the dope viscosity by adding polyphosphoric acid or re-dissolving the produced rigid heterocyclic polymer in polyphosphoric acid, any method can be adopted, and as a usable apparatus, for example, a vent type twin screw extruder And kneaders, nauter mixers, Banbury mixers, and multi-axis planetary kneaders.

In the production method of the present invention, the polyphosphoric acid used as the spinning dope solvent is particularly preferably polyphosphoric acid having a P ₂ O ₅ content of 80 to 84% by weight. The concentration of the polymer in the solution is preferably 5 to 25% by weight, more preferably 10 to 20% by weight. The solution forming the spinning dope is a lyotropic liquid crystal.

The production method of the present invention uses the spinning dope produced by the above method to produce rigid heterocyclic polymer fibers satisfying the following conditions (1) to (3).
(1) Extruding the dope from a spinneret installed in a spinneret holder controlled to a temperature range of 150 to 250 ° C.,
(2) The air gap length from the spinneret outlet to the coagulation bath is 1.0 cm or more,
(3) In the air gap portion, only the range from the spinneret outlet surface to the lower 3.5 cm is kept at a temperature of 30 to 250 ° C., or if the air gap length is less than 3.5 cm, the entire air gap portion Spinning is carried out at a temperature of 30 to 250 ° C.

  When the spinneret holder temperature is lower than 150 ° C., the viscosity of the dope becomes remarkably high and cannot be extruded from the spinneret, or the extruded dope is not sufficiently flexible and has a desired fineness and strength. Cannot be produced, which is not preferable. In addition, if the spinneret holder temperature is higher than 250 ° C., thermal degradation of the polymer becomes remarkable in the spinning process, which is not preferable. More preferably, the spinneret holder is controlled in a temperature range of 160 to 230 ° C.

Further, the distance from the spinneret outlet to the coagulation bath, that is, the air gap length is preferably 1.0 cm or more. The upper limit of the air gap length is not particularly limited, but is preferably 100 m (10 ⁴ cm) or less, more preferably 10 m (10 ³ cm) or less, still more preferably 5 m (5 × 10 ² cm) or less, and 1 m (100 cm) or less is even more preferable.

  Further, in the production method of the present invention, in the air gap portion, only the range from the spinneret outlet surface to the lower 3.5 cm is kept at a temperature of 250 ° C. or lower, or the air gap length is less than 3.5 cm. Spins while keeping the entire air gap portion at a temperature of 250 ° C. or lower. If the temperature range (hereinafter sometimes referred to as a hot zone) and the temperature range deviate from these ranges (including the case where the above range is maintained and other ranges are further maintained), the single yarn breaks in the spinning process. The spinning process becomes unstable and the fineness unevenness between the single yarns becomes remarkable, and the dope cannot be sufficiently stretched to the desired fineness. The temperature of the hot zone is preferably 30 ° C. or higher, more preferably 100 ° C. or higher, and further preferably 150 to 200 ° C.

  In the production method of the present invention, any method can be used as the method for keeping the hot zone above, for example, heated air or nitrogen is blown in a desired region between the spinneret outlet and the coagulation bath. A method of heating the cylindrical, slit-shaped or sandwich-shaped structure to a desired temperature to form a hot zone can be used.

  The atmosphere of the air gap may contain anything as long as it does not affect or interfere with solidification, and may be something like air, nitrogen, argon, helium, carbon dioxide.

  In particular, in the production method of the present invention, the air gap length is 3.5 cm or more, and the following range from the spinneret outlet surface to 3.5 cm below is kept at a temperature of 30 to 250 ° C. for spinning. Preferably, the heat retention temperature is more preferably 100 to 200 ° C.

  The dope extruded from the spinneret in the air gap is stretched. The maximum draft ratio (MDR) is used as a measure of whether or not the dope can be stretched. In the present invention, the MDR value is preferably 18.5 or more, and in the spinning process, it is preferable to perform spinning at a draft ratio of 2.0 or more. It is not preferred that the draft ratio during spinning is 2.0 or less because the obtained fiber does not have mechanical properties that can withstand practical use.

  The dope stretched at the desired draft ratio in the air gap enters the coagulation bath and is fiberized. A fluid that is not soluble in the rigid heterocyclic polymer is used for the coagulation bath, but it is preferable to use an aqueous solution in view of ease of handling and cost.

  In order to remove the acid component remaining in the fiber obtained by coagulation and spinning, it is necessary to wash the fiber. In the washing step, the washing is usually carried out by bringing it into contact with a fluid that is not soluble in the above-mentioned rigid heterocyclic polymer. The fluid may be a gas such as water vapor, but preferably a liquid and more preferably an aqueous solution. The cleaning may be performed in a single step or a multi-step process. Any number of washing steps may be performed before or after winding. Further, it may be performed separately before and after winding.

  In the production method of the present invention, it is preferable that the amount of residual phosphorus in the washed fiber is 1.0% by mass or less. If the amount of residual phosphorus in the fiber after washing is 3.0% by mass or more, the storage stability of the produced fiber is particularly deteriorated, and it becomes difficult to maintain a desired strength.

  Any method can be used as a method of drying the washed fibers. As such a drying method, a method of passing through a superheated furnace, winding it around a superheated roller, or passing it through hot air or reduced pressure is used. Drying is preferably performed at a temperature of 300 ° C. or lower in order to avoid the influence of thermal degradation and oxidation degradation of the rigid heterocyclic polymer of the present invention.

  In the present invention, heat treatment can be performed as necessary. For example, there is a heat treatment method of polybenzazole that passes through a well-known heating furnace under tension, and the method shown in the example of US Pat. No. 4,554,119 (Chenevy) is used together. Can do.

  In the production method of the present invention, the above-mentioned rigid heterocyclic polymer fiber can be spun relatively stably. In the spinning process, it is preferable that spinning can be performed at least about 0.1 km or more without causing a single yarn breakage, more preferably 0.5 km or more can be spun without causing a single yarn breakage, and about 1 km or more More preferably, spinning can be performed without causing breakage. The average tensile strength of the rigid heterocyclic polymer fiber obtained by the production method of the present invention is preferably at least about 1800 mN / tex or more, more preferably at least about 2000 mN / tex or more, and further preferably 2200 mN / tex or more.

The details of the present invention will be described more specifically by the following examples. However, the present invention is not limited to these examples.
The specific viscosity (η _inh ) is a value obtained by the following formula based on the relative viscosity (η _rel ) measured at 25 ° C. of a solution dissolved in methanesulfonic acid at a concentration of 2.5 mg / 8 mL.
η _inh = (lnη _rel ) / C
(In the above formula, η _rel is relative viscosity and C is concentration)
The tensile strength of the obtained fiber was measured with a Tensilon universal testing machine 1225A manufactured by Orientec Corporation.
The MDR in spinning was calculated by the following formula from the take-up speed at the point where the dope extruded from the die outlet was cut while increasing the take-up speed under each condition.
MDR = dope take-up speed (m / min) ÷ average flow rate of dope in capillary (m / min)
The fineness is a value obtained by measuring the weight (gram) per 10,000 m of a single yarn (unit: decitex).
Further, the stability during spinning was determined based on the following evaluation criteria.
A: During spinning, continuous winding was possible without causing breakage of a single yarn over 0.1 km or more.
X: During spinning, single yarn breakage occurred at a continuous winding length of 0.1 km or less.

[Reference Example 1] (Synthesis of pyridinedicarboxylic acid / 4,6-diamino-1,3-benzenediol salt)
191 parts by weight of 4,6-diamino-1,3-benzenediol dihydrochloride was dissolved in 1400 parts by weight of water deaerated with nitrogen. 150 parts by weight of pyridinedicarboxylic acid was dissolved in 2670 parts by weight of a 0.7M aqueous sodium hydroxide solution and degassed with nitrogen. An aqueous solution of 4,6-diamino-1,3-benzenediol dihydrochloride is dropped into an aqueous solution of disodium pyridinedicarboxylic acid over about 1.5 hours, and pyridinedicarboxylic acid / 4,6-diamino-1,3- A white precipitate of benzenediol salt was formed. At this time, the reaction temperature was maintained at 70 ° C. The obtained salt was filtered, and the powder solid on the filter paper was washed with 4000 parts by weight of water deaerated with nitrogen, and then dehydrated under vacuum conditions for 3 hours. The obtained powder solid was dried at 70 ° C. for 16 to 24 hours under vacuum to obtain pyridinedicarboxylic acid / 4,6-diamino-1,3-benzenediol salt.

[Reference Example 2] (Synthesis of 2,5-dihydroxyterephthalic acid / 4,6-diamino-1,3-benzenediol salt)
150 parts by weight of 4,6-diamino-1,3-benzenediol dihydrochloride was dissolved in 1100 parts by weight of water deaerated with nitrogen. 139 parts by weight of 2,5-dihydroxyterephthalic acid was dissolved in 2860 parts by weight of 0.5 M aqueous sodium hydroxide solution and degassed with nitrogen. An aqueous solution of 4,6-diamino-1,3-benzenediol dihydrochloride is dropped into an aqueous solution of disodium salt of 2,5-dihydroxyterephthalate over about 1.5 hours, and 4,6-diamino-1,3-3- A yellow precipitate of benzenediol / 2,5-dihydroxyterephthalate was formed. At this time, the reaction temperature was maintained at 70 ° C. The obtained salt was filtered, and the powder solid on the filter paper was washed with 4000 parts by weight of water deaerated with nitrogen, and then dehydrated under vacuum conditions for 3 hours. The obtained powdered solid was dried at 70 ° C. for 12 to 24 hours under vacuum to obtain 2,5-dihydroxyterephthalic acid / 4,6-diamino-1,3-benzenediol salt.

[Reference Example 3] (Preparation of polycondensation reaction and spinning dope)
450 parts by weight of pyridinedicarboxylic acid / 4,6-diamino-1,3-benzenediol salt obtained in Reference Example 1, 2,5-dihydroxyterephthalic acid / 4,6-diamino-1,3 obtained in Reference Example 2 -248 parts by weight of benzene diol salt, 1400 parts by weight of polyphosphoric acid, 900 parts by weight of diphosphorus pentoxide, and 4.96 parts by weight of tin chloride dihydrate were charged into a polymerization apparatus (biaxial planetary kneader) and replaced with vacuum nitrogen. Then, the polymerization apparatus was stirred for 30 minutes under the condition of the polymerization apparatus heat medium temperature of 80 ° C. Thereafter, the temperature of the heating medium was increased by 150 ° C. over about 90 minutes and stirred for about 1 hour and at a heating medium temperature of 160 ° C. for 1.5 hours. Thereafter, the dope temperature was raised to 160 ° C., and the mixture was further stirred for 3 hours at a dope temperature of 170 ° C. for 3 hours. The obtained dope was a viscous liquid. A part of the dope was collected, and the specific viscosity of a polymer sample obtained by reprecipitation using water as a poor solvent was measured to be 15.5 dL / g.

[Example 1]
The spinning dope obtained in Reference Example 3 was coagulated from a cap having a capillary diameter of 0.1 mm, a capillary length of 0.15 mm, and 100 holes using a gear pump (0.14 cc / rotation, 10 rotations / min) for quantitative extrusion. Extruded into the bath. The extruded dope was wound up in a washing bath at 26 m / min to obtain a fiber. At this time, the average flow rate of the dope in the capillary was 1.78 m / min. The distance (air gap) from the spinneret outlet to the coagulation bath was 66 cm, the spinneret holder temperature was set to 185 ° C., and a cylindrical part with a built-in heater was provided in the range from the spinneret to 3.5 cm below, 180 It was set to ° C. (Hot Zone 1). Table 1 shows MDR under these conditions, physical properties of the obtained fiber, stability during spinning, and the like.

[Example 2]
The spinneret holder temperature was set to 190 ° C., a cylindrical part with a built-in heater was provided in the range from the spinneret to 3.5 cm below, and it was set to 187 ° C. (hot zone 1). The operation was performed. The results are shown in Table 1.

[Example 3]
The spinneret holder temperature was set to 195 ° C., a cylindrical part with a built-in heater was provided in the range from the spinneret to 3.5 cm below, and it was set to 193 ° C. (hot zone 1). The operation was performed. The results are shown in Table 1.

[Example 4]
The same operation as in Example 3 was performed except that the air gap was 30 cm. The results are shown in Table 1.

[Example 5]
The same operation as in Example 3 was performed except that the air gap was 18 cm. The results are shown in Table 1.

[Example 6]
The same operation as in Example 3 was performed except that the air gap was 4 cm. The results are shown in Table 1.

[Comparative Example 1]
The spinning dope obtained in Reference Example 3 was coagulated from a cap having a capillary diameter of 0.1 mm, a capillary length of 0.15 mm, and 100 holes using a gear pump (0.14 cc / rotation, 10 rotations / min) for quantitative extrusion. Extruded into the bath. At this time, the average flow rate of the dope in the capillary was 1.78 m / min. The air gap was 66 cm, the spinneret holder temperature was set to 185 ° C., and a cylindrical part with a built-in heater was provided in the range from the spinneret to 3.5 cm below it, and set to 182 ° C. (hot zone 1). Further, a cylindrical part with a built-in heater having a length of 60 cm is provided below the hot zone 1, and the temperatures of the areas equally divided into three parts from the upper part to the lower part of the cylindrical part are respectively 190 ° C., 140 ° C., 90 ° from the upper part. It was set to ° C. (Hot Zone 2). Under these conditions, cutting of the extruded dope was frequently observed, making it impossible to produce fibers. The results are shown in Table 1.

[Comparative Example 2]
The same operation as in Example 1 was performed except that the dope pushed out from the spinneret installed in the spinneret holder set at 185 ° C. without winding a hot zone was wound up in a washing bath at 17 m / min. . The results are shown in Table 1.

  The production method of the present invention enables extremely stable production of rigid heterocyclic polymer fibers suitable for use in industrial materials such as rubber and plastic reinforcements, heat-resistant felt, and protective applications such as fire-fighting clothes and safety gloves. To do.

Claims (3)

The following formulas (A) and (B)

(N is an integer of 1 to 4, X is O, S or NH, Ar ¹ is a tetravalent aromatic group having 4 to 20 carbon atoms, and Ar ² is composed of 4 to 20 carbon atoms. And (n + 2) valent aromatic group)
And at least one first repeating unit selected from the group consisting of repeating units each represented by:
Formulas (C) and (D) below

(X is O, S or NH, Ar ³ is a tetravalent aromatic group having 4 to 20 carbon atoms, and Y ¹ and Y ² are N or CH, provided that at least one of Y ¹ and Y ² Either one is N),
In a method for producing a fiber from a spinning dope in which a rigid heterocyclic polymer composed of at least one second repeating unit selected from the group consisting of repeating units represented by each of the above is dissolved in polyphosphoric acid, the following (1) A method for producing a rigid heterocyclic polymer fiber, which satisfies the conditions (3) to (3).
(1) Extruding the dope from a spinneret installed in a spinneret holder controlled to a temperature range of 150 to 250 ° C.,
(2) The air gap length from the spinneret outlet to the coagulation bath is 1.0 cm or more,
(3) In the air gap portion, only the range from the spinneret outlet surface to the lower 3.5 cm is kept at a temperature of 30 to 250 ° C., or if the air gap length is less than 3.5 cm, the entire air gap portion Spinning is carried out at a temperature of 30 to 250 ° C. The rigid heterocyclic polymer according to claim 1 is represented by the following formula (i):
0.1 ≦ (a + b) / (c + d) ≦ 10 (i)
(A, b, c and d are the number of moles of each repeating unit represented by the above formulas (A), (B), (C) and (D), respectively)
And a specific viscosity measured at 25 ° C. of a solution dissolved in methanesulfonic acid at a concentration of 2.5 mg / 8 mL is 10.0 dL / g or more.   The production method according to claim 1 or 2, wherein the maximum draft ratio (MDR) during spinning is 18.5 or more.