JP3518643B2 - Method for producing polybenzazole fiber - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a fiber composed of a polybenzazole polymer such as polybenzoxazole or polybenzthiazole polymer.

[0002]

Polybenzazole fibers are obtained by extruding a dope containing a polymer and an acid solvent through a spinneret and stretching the dope filament until it is brought into contact with a coagulating fluid. During or after coagulation, the fiber bundle is converged into one or a plurality of yarns of various sizes.

When the spinning speed is increased to improve the productivity, the yarn breakage rate in the process is increased. It was a technical level that not only required labor for production due to yarn breakage but also reduced the production amount. On the other hand, when the spinning speed (process speed) was lowered in order to suppress the occurrence of yarn breakage, the productivity was not sufficient.

[0004]

SUMMARY OF THE INVENTION The present invention is intended to improve the process speed during the production of polybenzazole fiber, and relates to a production method for keeping the occurrence rate of yarn breakage low even if the spinning speed is increased.

[0005]

That is, the present invention is a method for producing fibers from a dope composed of polyphosphoric acid and a polybenzazole polymer by the following method. (a) The dope is extruded from the spinneret, (b) the extruded dope filament is stretched at least in the air gap, and (c) the dope filament is passed through a stress isolator in the air gap, and then (d) the dope is passed. Allow the filament to solidify. Further, the dope filament is drawn by a stress isolation device. Alternatively, the manufacturing method is characterized in that the spinning speed is about 600 m / min to 2000 m / min.

As shown in FIG. 1, a dope composed of polybenzoxazole, polybenzthiazole or polybenzazole polymer which is a copolymer of these is discharged from each hole of the spinneret 10 to form a dope filament 30. Let it form. Dope filament 3
0 can be converged during the process as shown as the fiber bundle 60.

The dope filament 30 is composed of 14 in FIG.
Then, a "gap" is run between the spinneret 10 and the coagulating liquid 74 as indicated by 16 in FIG. This gap is usually called the "air gap", but this part does not have to be air, and coagulability
It may be filled with a fluid that is not reactive or has little coagulation / reactivity.

The upper limit of the air gap length is not particularly limited, but it is desirable that it is not more than the self-weight cut length of the dope filament. Generally, the air gap length is at most about 100 m or less, more preferably 10 m or less, most preferably about 5 m or less. Further, the lower limit of the air gap length may be equal to or longer than the length capable of incorporating the stress isolation device. From the viewpoint that the dope deformation rate does not become too high and the stress becomes excessive, it is preferably at least 5 cm or more.

Reference numeral 20 in the figure represents a quench chamber. It can be provided just below the spinneret to partially cover the filament exiting the nozzle. It is preferable to provide the filament that has come out of the nozzle so as to be stretched under a relatively constant atmosphere, but it is not essential. The temperature of the fluid flowing into the quench chamber is approximately 0
It is preferable to keep the temperature from 100 ° C to 100 ° C. After leaving the quench chamber, the dope filament travels in the ambient atmosphere until it comes into contact with the coagulating liquid.

The dope filaments are stretched at least in the air gap to the desired thickness while the polymer orientation proceeds. Further, the filament may be converged on the yarn and then stretched, or may be stretched in plural times (in multiple stages). At this time, it may be stretched in multiple stages before it is converged, or may be brought into contact with the coagulating liquid in a wide width without being converged. In the case of stretching in multiple stages, generally, stretching is performed at a small magnification with respect to the first stretching immediately after exiting the nozzle. As long as the stretching is performed in the air gap, the stretching method, the arrangement and the type of the stretching device, etc. may be arbitrary. Since stretching is not easy after solidification, it generally reaches the winding speed in the air gap, and after solidification it is kept at the same speed until it is wound up.
The spin draw ratio, defined as the ratio of the discharge linear velocity from the dope nozzle and the winding velocity, is at least about 1.
It is preferably 0 or more, more preferably about 20 or more, still more preferably 40 or more. The spinning of the polybenzazole polymer can be carried out according to the known method as disclosed in US Pat. No. 5,296,185 or according to US Patent Application No. 207,989 filed on Mar. 8, 1994.

The air gaps 14, 16 of FIGS. 1 and 2
Is provided with a stress isolation device 25, which is a pair of rollers 40 and 50 without a drive. After running over the surfaces of rollers 40 and 50, the dope yarn comes into contact with a liquid that is insoluble in the polymer. In FIG. 1, after coming into contact with the coagulation liquid 74 at the coagulation funnel 70, it is guided to the take-up device 85 and further wound up by the winder 110. In this case, the take-off device 85 includes drive rollers 90 and 100.
It is composed of. In FIG. 2, the dope yarn 60 is in contact with the coagulating liquid 74 in the coagulating bath 72 and the drive rollers 90 and 10
After traveling over 0, it is wound up by the winder 110.

In the method shown in FIG. 3, the dope filament 30 discharged from the spinneret 10 is converged on the dope yarn 60, and the dope filament 30 is passed through a take-up device 85 composed of drive rollers 42 and 44. The dope filament 30 discharged from the spinneret is stretched by the take-up device 85 until it has a desired thickness. The drive rollers 42 and 44 also function as a stress isolation device. The dope yarn 60 is a solidification funnel 70.
Contact with coagulation liquid at. The solidification yarn 80 is driven by the drive roll 9
It is guided to 0 and 100 and wound up by the winder 110. At this time, it is possible to form an independent stretching zone by making the number of rotations of the roller different between the take-up device 85 and the drive rolls 90 and 100.

Although not based on a strict theory, the effect of placing a stress isolation device in the air gap is considered as follows. When the filament comes into contact with the coagulating liquid, vortices generated in the coagulating liquid, turbulence of the liquid surface, and other disturbance factors occur. It is expected that the yarn breakage level will be improved in the long term by preventing such disturbance from being transmitted to the high temperature soft dope filament that has just been discharged from the nozzle. In the absence of a stress isolation device, it is necessary to reduce the process speed in order to suppress the disturbance to the stretched portion of the air gap generated in the portion in contact with the coagulating liquid. From the viewpoint of operability of production, the level of yarn breakage is preferably about 4 times or less, more preferably about 2 times or less, still more preferably about 1 time or less per 2 days on average.

The stress isolation device for reducing the disturbance that causes yarn breakage may be other than that shown in the figure. In general, it is important to reduce the disturbance transmitted to the position where the dope is separated from the nozzle, which is generated in the back side process such as contact with the coagulating liquid. Any device may be used as long as it has such a function.

An example of an effective stress isolation device is a solid wall, non-rotating guide ("Dic" by Hoechst Celanese).
tionary of Fiber & Textile Technology "1990 version 7
(As shown on page 4), shoes, single rolls, driven or non-driven rolls. The drive roll can function as a stretching device at the same time as the stress isolation function. As the material, an acid-resistant metal or ceramic, or a base material coated with an acid-resistant metal or ceramic can be used. The stress isolator may be used at any position from the extrusion of the dope to the solidification, but the optimum position is the process speed, the stretching condition,
It is determined according to various conditions such as the properties of the dope. Generally, it is preferably provided after or immediately after the dope is cooled and solidified. The position of the stress isolation device can be optimized by moving from the extrusion to the solidification and searching for the position where the yarn breakage is minimized.

The stretching before solidification may be performed by any device as long as it can stretch the dope filament that has been cooled and solidified. Generally, the purpose of stretching the dope filament is to obtain the desired thickness (fineness).
And improving the orientation of the polymer.
The size of the stretch is such that the desired fineness and physical properties can be achieved within the stretchable range. An example of an effective stretching device is a drive roll whose yarn contact portion is made of an acid resistant material. It is also possible to carry out multi-stage stretching in two or more sets of rollers. It is possible to converge the filaments either before or during the series of stretching devices or after exiting the group of rollers. In addition, the position of the roller group can be optimized according to various conditions, so that a specific setting can be made between the extrusion and the solidification.

The spinneret preferably has about 50 to about 1500 holes, more preferably about 100 to about 1000 holes, and even more preferably about 150 to about 750 holes. The single yarn denier is preferably about 1 to about 3 dpf, more preferably about 1 to about 2.5 dpf, more preferably about 1.5 dpf. Generally, the convergent yarn size is at least about 50 denier or more,
It is preferably about 350 denier or more, more preferably about 400 denier or more. Also, at most about 5,000 denier or less, preferably about 4500
It is denier or less, more preferably about 2500 denier or less. The preferred pore size is approximately 0.1 to 0.
It is 5 mm, preferably 0.15 to 0.25 mm.

The dope filament is solidified by extracting the solvent from the filament using a fluid which is a non-solvent for the polymer and which can dilute the solvent. Preferred coagulating liquids include water and phosphoric acid aqueous solution. The coagulation can be carried out by bringing the dope filament and the coagulating liquid into contact with each other to efficiently extract the solvent from the filament.
Generally, the coagulation step can be carried out by passing the thread through a coagulation funnel or spray or bath. The coagulation process is performed according to US Pat. Nos. 4,896,860 and 4,298,565, and US Patent Application No. 08/11.
The method described in No. 0,149 etc. can be used.

After being solidified and solvent-extracted and converged on the yarn, it is dried, and these steps can be carried out by a known method. Further, a heat treatment step may be carried out for the purpose of improving the elastic modulus of the fiber. These steps are described in U.S. Pat. Nos. 5,288,452 and 5,288,455 and U.S. Pat. App. No. 162,724 (199).
(November 3, 2013) and U.S. Patent Application No. 142,5
No. 26 (filed on November 2, 1993) and the like can be used.

The process speed of coagulation or extraction is set to the highest speed after optimizing the performance of the product. Generally, the process speed does not exceed about 10,000 m / min, preferably about 5000 m / min or less, more preferably about 2000 m / min or less. Further, it is about 200 m / min or more, more preferably 400 m / min or more, and further preferably about 600 m / min or more.

The present invention relates to a lyotropic liquid crystalline polybenzazole polymer, namely polybenzoxazole,
A spinning stock solution containing polybenzothiazole or a copolymer thereof is used. The polybenzazole polymer used here is the "Liquid Crystalline" by Wolfe et al.
Polymer Compositions, Process and Products '' USPa
tent 4,703,103 (October 27,1987); Wolfe et al., "Liqui.
d Crystalline Polymer Compositions, Process and Pro
ducts ”US Patent 4,533,692 (August 6,1985) ； Wolfe
Et al. `` Liquid Crystalline Poly (2,6-Benzothiazole)
Compositions, Process and Products '' US Patent 4,5
33,724 (August 6,1985); Wolfe et al., "Liquid Crystall"
ine Polymer Compositions, Process and Products '' U.
S.Patent 4,533,693 (August 6,1985); Evers "Thermox
datively Stable Articulated p-Benzobisoxazole p-Be
nzobisthiazole Polymers '' US Patent 4,359,567 (Nov
ember 16,1982) ； "Method for Making Hete by Tsai et al.
rocyclic Block Copolymer Compositions, Process and
Products "USPatent 4,578,432 (March 25,1986); 1
1 Ency.Poly.Sci. & Eng., `` Polybenzothiazoles and Po
lybenzoxazoles '', 601 (J. Wiley & Sons 1988) and W.
W. Adams et al. `` The Materials Science and Engineering
of Rigid-Rod Polymers '' (Materials Research Societ
y 1989) and random, sequential, block copolymers of PBO, PBT and PBO, PBT.

The polymer can be AB type as represented by chemical structural formula 1 (a) and / or AA / BB type units as represented by chemical structural formula 1 (b).

[0023]

[Chemical 1]

[0024]

[Chemical 2]

[0025]

[Chemical 3]

In the formula, each Ar represents an aromatic group selected from lyotropic liquid crystal polymers (that is, forming a liquid crystal domain above the critical concentration point) polybenzazole polymer. The aromatic group may be a heterocycle such as a pyridinylene group, but preferably forms a ring with carbon. The aromatic group may be a condensed polycyclic group ring or a non-condensed polycyclic group, but one 6-membered ring is preferable. Although the size is not limited, the aromatic group preferably contains 18 or less carbon atoms, more preferably 12 or less carbon atoms, and further preferably 6
It preferably contains up to 4 carbon atoms. Ar1 of the AA / BB type unit preferably has a 1,2,4,5-phenylene structure or an analog thereof. Ar of the AB type unit preferably has a 1,3,4-phenylene structure or an analog thereof. Each Z is independently an oxygen atom or a sulfur atom. Each DM is a divalent organic structure selected from polybenzazoles which are directly bonded or lyotropic liquid crystal polymers independently of each other. As the divalent structural unit, the above-mentioned aromatic group (Ar) is preferable. Especially 1,
A 4-phenylene structure or its analogue is preferred. The nitrogen atom and Z structure of each azole ring are bonded to the carbon atom of the adjacent aromatic group to form a condensed form of the 5-membered azole ring and the aromatic group. The azole ring of AA / BB type unit is described in 11 Ency.Poly.Sci. & Eng., “Polybenz.
othiazoles and Polybenzoxazoles '', 601 (J. Wiley & S
ons 1988).

The polymer is preferably composed of AB-PBZ repeating units or AA / BB-PBZ repeating units, more preferably essentially AA / BB-PBZ repeating units. The azole ring in the polymer is preferably an oxazole ring in which Z is an oxygen atom.

The repeating unit used in the present invention has the structural formula (a)-
Those shown in (h) are preferred. More preferably structural formula
Those shown in (a)-(f) are preferred, and more preferably the structural formula
Those shown in (a)-(d) are preferable.

The PBZ polymer preferably has at least about 25 or more repeating units on average, more preferably at least about 50 or more repeating units, and further preferably at least about 1 or more.
It is preferable to have a repeating unit of 00 or more. AA /
The intrinsic viscosity of the BB-PBZ rigid linear chain is preferably at least about 10 dl / g or more, more preferably at least about 15 as measured by methanesulfonic acid at 25 ° C.
It is preferably dl / g or more, more preferably at least about 20 dl / g or more. For some applications, the intrinsic viscosity is optimally at least about 25 or 30 dl / g. The intrinsic viscosity is 60
It may be dl / g, but is preferably 40 dl / g.
The intrinsic viscosity of the semi-rigid AB-PBZ polymer is preferably at least about 5 dl / g, more preferably at least about 10 dl / g, and even more preferably at least about 15 dl / g. Something is preferable.

This polymer or copolymer is dissolved in a solvent to prepare a solution or dope. Polybenzoxazole and polybenzothiazole can be dissolved in cresol,
It is preferable to use a soluble acid as the solvent. The acid has good non-oxidizing property. As an example of a preferable solvent, polyphosphoric acid,
Methane sulfonic acid, sulfuric acid and mixtures thereof may be mentioned. More preferably, the acid is polyphosphoric acid and / or methanesulfonic acid. Polyphosphoric acid is more preferable.

The dope concentration is preferably sufficient to form filaments after spinning and solidification in spinning. More preferably, the concentration is sufficient to form a lyotropic liquid crystal phase. Preferably, the polymer concentration is at least about 7 weight percent or greater, more preferably at least about 10 weight percent or greater, and even more preferably at least about 14 weight percent or greater. Maximum polymer concentration is primarily constrained by workability such as polymer solubility and dope viscosity. Rarely dopes with a polymer concentration of 30 weight percent are used, and typically 20 weight percent or less are used.

[0032]

The following examples are for purposes of illustration only, and are not limiting on either the specification or the claims of the present invention. All quantities and percentages are by weight unless otherwise noted.

The intrinsic viscosity is 23 ° C. after being dissolved in methanesulfonic acid which is almost like an anhydride at a concentration of 0.046 g / dL.
It was measured at. The phosphorus concentration in the fiber was measured by the fluorescent X-ray method.

Example 1 and Comparative Example 1 A polyphosphoric acid solution prepared by dissolving 14% by weight of a cis-polybenzoxazole polymer having an intrinsic viscosity of about 33 dl / g was maintained at 178 ° C. in a 42-hole pore size 0.22 mm spinneret. From 0.24 g / min per single hole.

Through a free roller installed at a position 142 cm from the spinneret, a coagulation bath storing room temperature ion-exchanged water at a position 282 cm away from the spinneret was introduced at a spinning speed of 200 m / min. . The driving roller speed provided in the coagulation bath was set to 200 m / min. From the coagulation bath, the yarn was passed through a washing bath and a drying device and wound up (Example 1). Frequency of thread breakage (spinnability)
Was 0.02 times / hour, which was extremely good.

An experiment was conducted in the same manner as in Example 1 except that the free roller of Example 1 was not provided and that the distance between the spinneret and the coagulating bath was 43 cm (Comparative Example 1). The frequency of yarn breakage (spinnability) in this method was 0.04 times / hour.

The values of strength, elastic modulus and elongation of the fibers obtained in Example 1 and Comparative Example 1 are shown in Table 1.

[0038]

[Table 1]

In this example, it can be seen that by installing a stress isolation device in the air gap, spinnability is improved without changing fiber properties.

Examples 2 and 3 and Comparative Examples 2 and 3 The same apparatus as in FIG.
% Polyphosphoric acid solution kept at 170 ° C.
It was extruded from a nozzle having a hole shape of 0.18 mm at a discharge rate of 39.5 g / min. Single hole discharge rate at this time is 0.24 g /
Min, the shear rate on the hole wall surface was about 3500 per second. The dope filament was passed through a pair of godet rolls 44 provided at a position 70 cm from the spinneret, and then passed through a coagulation bath filled with ion-exchanged water at room temperature provided at a position 142 cm from the spinneret. The process speed was 200 m / min and the spin draw ratio was about 42 (Example 2). The frequency of yarn breakage at this time was 0.02 times / hour.

Example except that a spinning funnel supplied with the same coagulating liquid as in Example 2 was provided at a position 70 cm from the spinneret and the coagulated filaments exiting the funnel were passed through a pair of godet rolls 100 for spinning. An experiment was performed under the same conditions as in 2 (Comparative Example 2). The frequency of yarn breakage at this time was 0.04 times / hour.

The same apparatus as in Example 2 was used, but the pore size was 0.21 m.
The same experiment as in Example 2 was carried out with respect to Example 3 and Comparative Example 2 except that a m 166-hole nozzle was attached and the dope discharge amount was doubled to 0.48 g / min per single hole to make the spinning speed 400 m / min. An experiment in which the same changes were made will be referred to as Comparative Example 3.

Even when the process speed was increased to 400 m / min, the yarn breakage frequency of Example 3 was 0.04 times / hour and the spinnability was good, whereas in Comparative Example 3, The yarn breakage frequency was 0.08 times / hour and the spinnability was insufficient. As shown in Table 2, there is no significant difference in the fiber physical properties even when the stress isolator is a driving roller.

[0044]

[Table 2]

Examples 4, 5 A device similar to that shown in FIG.
% Polyphosphoric acid solution kept at 170 ° C.
It was extruded from a nozzle having a hole shape of 0.18 mm at a discharge rate of 39.5 g / min. Single hole discharge rate at this time is 0.24 g /
Min, the shear rate on the hole wall surface was about 3500 per second. The dope filament goes through a pair of godet rolls rotating at a surface speed of 180 m / min provided at a position 70 cm from the spinneret, and further rotates at a surface speed of 200 m / min provided 30 cm below the spinneret. After passing through a pair of godet rollers, it was passed through a coagulation bath filled with ion-exchanged water at room temperature provided at a position of 142 cm. The spin draw ratio was about 38.2, and the draw ratio between the two pairs of godet rolls was about 1.1 times (Example 4). The frequency of yarn breakage at this time was 0.04 times / hour.
The speed of the godet roll near the spinneret is 200m /
Example 5 is an experiment in which the spin draw ratio is about 42, and the draw ratio between two pairs of godet rolls is about 1.0. The frequency of yarn breakage at this time was 0.04 times / hour.

[0046]

[Table 3]

Spinning in a stable state with less frequency of yarn breakage
It can be stretched. Regarding the physical properties of the fiber, as shown in Table 3, the strength and elastic modulus are improved by stretching before solidification.

[Brief description of drawings]

FIG. 1 is a schematic view of an example of a manufacturing process of the present invention.

FIG. 2 is a schematic view of an example of a manufacturing process of the present invention.

FIG. 3 is a schematic view of an example of a manufacturing process of the present invention.

[Explanation of sign]

10: Spinneret, 14, 16, 17: Air Gap, 20: Quench Chamber, 25: Stress Isolator, 30: Dope Filament, 40, 50: Roller without Drive, 60: Dope Yarn, 7
0: coagulation funnel, 72: coagulation bath, 74: coagulation liquid,
80: coagulated yarn, 90, 100: drive roller, 11
0: Winder

Front Page Continuation (72) Inventor Michael E. Mills 48642 Midland Avalon Street, Michigan, USA 1604 (72) Inventor Douglas Etrek 48642 Midland Arbutus Court, Michigan, USA 2575 (56) Reference JP-A-8-49156 (JP, 49,156) A) International publication 94/12701 (WO, A1) James F. Wolfe, Encyclopedia of polymer science and eng inering 2nd edition, USA, 1988, Vol. 11,625-628 (58) Fields investigated (Int.Cl. ⁷ , DB name) D01F 6/74 D01D 5/06

Claims (3)

(57) [Claims] 1. A method for producing fibers from a dope composed of polyphosphoric acid and a polybenzazole polymer by the following method. (a) The dope is extruded from the spinneret, (b) the extruded dope filament is stretched at least in the air gap, and (c) the dope filament is passed through a stress isolator in the air gap, and then (d) the dope is passed. Allow the filament to solidify. 2. The manufacturing method according to claim 1, wherein the dope filament is drawn with a stress isolation device. 3. A spinning speed of about 600 m / min to 20.
Claim 1 characterized in that it is 00 m / min.
The manufacturing method according to the item.