JPS591710A - Poly(p-phenylene terephthalamide) fiber of novel structure and its preparation - Google Patents

Abstract

PURPOSE:A dope of poly(p-phenylene terephthalamide) is extruded into a noncoagulating fluid, then the coagulating bath and taken up under drafting to produce the titled fiber with high knot strength and resistance to fibrilation. CONSTITUTION:Poly(p-phenylene terephthalamide) is dissolved in sulfuric acid or a solvent mainly consisting thereof to make a spinning dope of more than 15wt% polymer concentration. The resultant dope is extruded through the spinneret into a noncoagulating fluid, then into the coagulating bath kept at a temperature lower than -5 deg.C and taken out of the bath at such a speed as the draft exceeds 1.5, washed with water, dried to produce the titled fiber of 1.41g/cm<3> density, lower than 30 deg. crystal orientation angle with no stripe patterns of high density in the direction perpendicular to the fiber-length direction on the observation with a polarization microscope.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a porous film having a novel microstructure. j (p-phenylene terephthalamide) (hereinafter sometimes abbreviated as PPTA) Ni fiber and its manufacturing method, and more specifically, it has an agglomerated structure and therefore has high strength, high Young's modulus, and nodule strength. The present invention relates to a PPTA fiber that has a large diameter and does not easily fibrillate, and a special method for producing the same.

PPTA is a polymer that has been known for a long time.
! It was expected that the +1 straight molecular structure would yield fibers with excellent heat resistance and mechanical properties. However, since it is poorly soluble in PPTA's organic solvent, Cipriani proposed a basic method of wet spinning using concentrated sulfuric acid as a solvent (Japanese Patent Publication No. 38-18573), but Cipriani's method itself was not industrialized. On the other hand, it has long been known both theoretically and experimentally that when a rigid polymer is dissolved in a solvent, it forms liquid crystals at a certain degree of polymerization, at a certain concentration, and at a certain temperature. (P
, J. Flory: Prec, Roy, Soc.
e73 (1956)). If a polymer solution exhibiting optical anisotropy in a liquid crystal state can be ejected from a nozzle and solidified without disturbing the orientation of the liquid crystal inside the nozzle as much as possible, it will have high strength, a high Young's modulus, and a highly It is easily expected that fibers with oriented molecular chains can be produced. In fact, Kuorek proposed a wet spinning method for a concentrated solution of these aromatic polyamides, which have a rigid and linear molecular structure, in the form of a liquid crystal forest. Ta. However, even with Kuwolek's method, the spun fibers need to be further heat-stretched in order to obtain useful high strength.
This thermal tension inevitably leads to an increase in strength and king rate, but on the other hand, it has the disadvantage of decreasing elongation.

Blaze is produced by spinning an optically anisotropic dope with a high concentration by air-discharge wet spinning.91
discloses that the fiber in the green state has high strength and improved elongation compared to the method of Kuwolek (Japanese Patent Application Laid-open No. 47-39
458 Publication), and furthermore, by subjecting this fiber to tension heat treatment, a high Young's modulus can be obtained (Japanese Patent Application Laid-Open No. 47-1999).
Publication No. 45419). Then, the PPTA fiber obtained by such a method is used as Kevlar or Kevlar 49 to cover the fabric.

However, the disadvantage of these fibers is that they are prone to fibrillation [e.g., S. L. Phoenix et al.: Text.
Res, J, December issue, page 934 (1974))
.

It is susceptible to buckling and a so-called kink band occurs [for example, M, G, Dobb et al.; Polymar Vol. 22, No. 960
Page (1981) 3, etc. have been pointed out.

Furthermore, the knot strength is extremely weak compared to the tensile strength, resulting in brittleness, which is thought to be unavoidable, and the knot strength has been improved by means of copolymerization. For example, Yabuki et al: f#! Journal of the Institute of Technology Vol. 34 No. T-5
42 pages (197B)).

The present invention differs from such a position, in manufacturing PPTA fibers by employing very special methods and conditions that have not been implemented in the past.
This is based on the knowledge that it has a unique microstructure not seen in A fibers, and therefore eliminates the above-mentioned drawbacks found in conventional high-strength PPTA fibers. I should mention the structure. Kevlar coated or Kevlar 491 known method (for example, the method disclosed in Japanese Patent Application Laid-open No. 47-39458)
Tane and Wei produced this by polarizing microscope observation (approximately 100
(~1000x magnification), a dense striped pattern is seen in the direction perpendicular to the fiber length direction, as shown in FIG. 1, without exception. This is what Dobb et al. (J. Polym. Sci.
Polym.

Phyo, Volume 15, Page 1i2201 (1977
)) It is presumed that this is related to the so-called pleated sheet structure. In addition, Kevlar coated with Kevlar or Kevlar 49% known methods (for example, JP-A-47
When the crystal structure of this product was examined by X-ray diffraction, large diffraction peaks were observed at 20-23 degrees and 20-21 degrees on the equator line, without exception. [Figure 2 l)], Takayanagi et al.
Appl, Polym.

It can be said to be a ■-type crystal according to the definition of ``Set.

Takayanagi et al. proposed the ■ type as another crystal form of PPTA. It also states that in the production of PPTA film, L-type or ■-type crystals are generated depending on the choice of coagulant, but nothing is mentioned about fibers.

The present invention can be applied to PPTA under special conditions that have not been implemented in the past.
Novel agglomerated structure when producing fibers.

In other words, it is based on the new knowledge that it has a structure in which dense horizontal stripes are not observed even when observed with a polarizing microscope, and that it preferably has a ■-type crystal shape. This invention is based on the unexpected discovery that although the Young's modulus is low, it has excellent nodule strength and is difficult to fibrillate. That is, the first aspect of the present invention is that the density of at least 1.411/flaw 3, 30° Poly(p-
This poly(p-phenylene terephthalamide) fiber is characterized by being made of scarlet fiber and having no dense striped pattern observed in a direction perpendicular to the fiber length direction when observed under a polarizing microscope. The second aspect of the present invention is that a dope in which p-phenylene terephthalamide (p-phenylene terephthalamide) is dissolved in sulfuric acid so as to have a concentration of sulfuric acid is placed in a non-coagulable fluid through a spinneret, and then maintained at a concentration of less than 5C. Poly(p-phenylene terephthalamide) fJI' fibers are extruded into a coagulating bath, drawn out from the coagulating bath at a draft of at least 1.5, washed with water and dried. Furthermore, the third aspect of the present invention is Bo! j (p-phenylene terephthalamide) in sulfuric acid or a solvent mainly composed of sulfuric acid.
The dope dissolved to a polymer concentration of 5% by weight is extruded through a spinneret into a non-coagulable fluid and then into a coagulation bath maintained at less than -5C and coagulated at a rate of at least 1.5% draft. After pulling out the coagulated filament from the bath and washing it with water, it was heated to 200 m
This is a method for producing poly(p-phenylene terephthalamide) 1 fiber, which is characterized by heat treatment at ~550C.

The fibers of the present invention consist essentially of PPTA. Here, "essentially" means 1. Polymers other than PPTA (for example, poly(m-phenylene terephthalamide)% poly(p-phenylene terephthalamide) iso7talamide)
S poly-(m-phenyleneiso7talamide), poly-
(polymethylene terephthalamide), aliphatic polyamide, alicyclic polyamide, polyester, polyimide, polyurethane, polyurea, etc.], P, PPT
Ag and other repeating units (for example, nuclear-substituted p-phenylene units, nuclear-substituted mata are unsubstituted biphenylene units, 0-phenylene units, 1m-phenylene units, (poly)methylene units, pyridylene units, and esters) , urethane, urea, ether, thioether, etc.)
may be copolymerized, or various additives and compounding agents (for example, dyes, antioxidants, ultraviolet absorbers, brighteners, pigments, etc.) may be added.

The fibers of the present invention should have a density of at least 1.41 flos''. If the density is less than 1.41 flos, the fiber will have many cracks and voids and will have an extremely high degree of crystallinity. Fibers with low density indicate that they have a non-uniform cohesive structure.

It may be obtained by wet spinning directly from a spinneret into a coagulation bath or by spinning with an extremely small draft. For strength and nodule strength to be at a very desirable level, PPT with a density of at least 1.45 t/(m")
Am fiber is preferred. The density of the PPTA fiber of the present invention can be measured by a conventional method using toluene and carbon tetrachloride at 25C using a density gradient tube. According to the method used, it should have a crystal orientation angle of 60° or less, as measured for the 2θ-26° diffraction peak. This is because PPTA fibers that do not satisfy this stability have low strength and Young's modulus.

This is because the value as an industrial fiber decreases. Preferably, the fibers have a crystal orientation angle of 256 degrees or less.

When the fiber wire of the present invention is observed under a polarizing microscope, it is important that no dense striped pattern is observed in the direction perpendicular to the fiber length direction.

As mentioned above, this is thought to be related to the pleated sheet-like aggregate structure. Although striped patterns can be recognized by ordinary optical microscopy, they can be observed using a polarizing microscope.
When observed in orthogonal Nicols or near orthogonal Nicols,
It is observed more clearly as stripes with various colors, as shown in Figure 1.

The magnification for polarized light microscopy is usually 100 to 100.
0 times is sufficient. Note that normal measures such as using an immersion liquid such as olive oil or methylene iodide may be used during observation. It is difficult to quantify the distance between fringes using only polarized light microscopic observation. Thus, "closely striated" means spacing that is less than % of the diameter of the fibers. It has been found that fibers produced by conventional methods typically have stripes spaced at or less than four fiber diameters apart, as shown in FIG. Although the claims specify that the direction of the striped pattern is "perpendicular to the fiber length direction," this does not mean that it is strictly perpendicular, but rather that it is approximately perpendicular. .

The fibers of the present invention have high density, high orientation, and do not have a striped pattern, so they have excellent characteristics such as high strength, high Young's modulus, excellent knot strength, and resistance to fibrillation. It can also be expected to have excellent buckling properties. In comparison, conventional PPTA fibers have some drawbacks in these respects. For example, Kepler, Kepler 49% Japanese Patent Application Publication No. 47-39458, Japanese Patent Application Publication No. 47-39458,
7-45419 % PPTAM' fibers obtained in Examples such as JP-A-122012 have a striped pattern in the direction perpendicular to the la fiber length direction, so they have poor knot strength. inferior and easily fibrillated. Furthermore, the PPTA fibers obtained by the method disclosed in Japanese Patent Publication No. 47-2489 and Japanese Patent Publication No. 50-8474 had a density of less than 1.41 t/()113 due to the disordered agglomerated structure, and had low strength. 9. The elongation is low and the knot strength is extremely low.

The fiber of the present invention preferably has a -type crystal structure.

This is because, surprisingly, the improvement in nodule strength becomes even more remarkable when the crystal structure of the ■type is partially present.Here, a method for determining the ■type and ■type will be described. A diffraction pattern is obtained by irradiating the sample PPTA fiber with X-rays from a direction perpendicular to the fiber length direction using a conventional method. Pay attention to the diffraction peak in the equatorial direction of the diffraction pattern (for example, the second
As shown in the figure, the diffraction intensity on the equatorial line is 20-16~3
(record within 0° range). At this time, in addition to the large diffraction peak at 2θ-23°, the one with a diffraction peak at 2θ-21° (Ca in Figure 2) is type I crystal, and (0 in Figure 2)
A crystal in which a diffraction peak appears at 20s18° is defined as a ■-type crystal. Note that when the ■-type and ■-type are present together, both the 2θ-1f and 20-23° diffraction peaks will be observed.

The fibers of the present invention have a logarithmic viscosity (ηi
nh; Dissolved in 98% sulfuric acid at 0.5fldJ degrees,
It is desirable to have a value measured using a conventional method at 25U. This is because fibers made of PPTA with a high degree of polymerization generally have a large strength. More preferably, ηi
nh≦4.0.

Although the fibers of the present invention are not particularly limited in their thickness, fibers having a diameter of 0.1 to 10 deniers are generally preferred because they have excellent strength and knot strength.

The fibers of the present invention have microstructural features such as density, crystal orientation angle, and no striped pattern observed under polarized light microscopy. Strong and thick, difficult to form into fibrils. Moreover, when it has a ■-type crystal structure, these characteristics become even more remarkable.

In addition to these characteristics, strength decreases at high temperatures.

The fiber of the present invention, which has been found to have excellent performance such as chemical resistance, can only be produced by a specially specified method and conditions, and this manufacturing method is the second and second method of the present invention. PPTA
It is necessary to prepare a dope in which the polymer is dissolved in sulfuric acid or a solvent mainly composed of sulfuric acid to a polymer concentration of at least 15% by weight. At this time, PPTA, as mentioned earlier,
If necessary, a small amount of other components may be copolymerized or a small amount of blended with other polymers may be used. In addition, since PPTA causes a slight decrease in the degree of polymerization in the doped state, taking this into account,
It is sufficient to determine the degree of polymerization of In the fiber of the present invention, in order to ensure desired level of physical properties, l'P T
Preferably, A will have a logarithmic viscosity of about 3.5 or greater. PPTA, for example,
It can be obtained by the method described in Publication No. 99.

The solvent used to prepare the dope is sulfuric acid or a mixture based on sulfuric acid. The sulfuric acid is preferably concentrated sulfuric acid with a concentration of about 96M or more from the viewpoint of percent solubility. It may also be so-called fuming sulfuric acid.

Examples of substances that can be mixed with sulfuric acid include chlorosulfuric acid, fluorosulfuric acid, dichloroacetic acid, acetic acid, phosphorus pentoxide, and nitrobenzene. Polymer concentration is 15% by weight
It is necessary that it is above.

This is because fibers spun from dope generally have low density and low strength. The polymer concentration is preferably 1
It is 7% by weight or more. At such polymer concentrations,
Dope often needs to be slightly warmed. As the temperature increases, the rate of deterioration of the polymer in the dope increases, so it is undesirable to expose it to very high temperatures for a long time. usually.

Dopes with temperatures ranging from 120C to 120C are used. The dope used in the present invention exhibits optical anisotropy in most cases.

The dope may contain conventional additives 5 such as antioxidants, ultraviolet stabilizers, etc.

The dope thus prepared must be extruded through a spinneret into a non-coagulable fluid and then into a coagulation bath maintained at less than -5C. The dope is deaerated, filtered, and weighed before passing through the spinneret.It is preferable especially for industrial production.There are no particular restrictions on the shape of the spinneret, the number of holes, the size of the holes, etc. It's not something you can earn. The diameter of the holes used is usually 0.01 to 5 mm. The linear speed of the dope extruded from the spinneret is not particularly limited, and is mainly used to improve productivity and the required draft blade φ, which will be described later.
It may be decided based on the request of the case etc. It is essential that the dope stream extruded from the spinneret pass through a non-solidifying fluid. This is because when extruded from a spinneret into a solid coagulation bath without passing a non-coagulation fluid, the iT.

It is difficult to increase the draft by more than 1.5, because the resulting fibers have low density, strength, and elongation. Non-coagulable fluids may include gases such as air, nitrogen, argon% oxygen, and liquids such as toluene and heptane.

9-ki is most preferable due to its economic advantages and operability.

The appropriate thickness of the non-coagulable fluid is about 0.2 to 50 mm.

The dope stream extruded into the non-coagulable fluid must then be extruded into a coagulation bath held below -5C where it undergoes coagulation. In the present invention, the coagulation bath must be maintained at -5C or lower, and from this point of view, the types of coagulation liquid that can be used are limited. The coagulating liquid that can be used is, for example, 10 to
71. Sulfuric acid aqueous solution, ethylene glycol or ethylene glycol aqueous solution, or a mixture thereof with sulfuric acid, methanol or methanol aqueous solution, or a sulfuric acid aqueous solution with a concentration of 80%, preferably 15 to 60 M%. and sulfuric acid, acetone or acetone aqueous solution, or a mixture of these and sulfuric acid.

In carrying out the present invention, basically any kind of coagulating liquid can be used as long as the temperature can be lowered to 15C or less, but the above example is given from the point of view of ease of implementation.
An aqueous sulfuric acid solution is most preferred from the viewpoint of ease of industrial implementation and low cost.

It is extremely important that the coagulation bath temperature be below 15C. This is because only when the coagulation bath temperature is -5C or lower, PPTAfsy fibers with no so-called striped pattern, which is a characteristic of the fibers of the present invention, are formed, and the favorable property of high knot strength and resistance to fibrillation is achieved. Furthermore, the fibers of the present invention spun at a coagulation bath temperature of 15C or lower have excellent gloss.The coagulation bath temperature is preferably 110C or lower, more preferably 115C or lower. In such a case, the ■-type crystal structure becomes predominant, and the improvement in nodule strength becomes even more remarkable.

Regarding the coagulation bath temperature, prior literature generally states that low temperatures can be used, but these are only described as a general range and do not mention anything about its special properties or usefulness. do not have. Rather, it should be said that in the case of difficulty in implementation or industrial implementation, energy disadvantages could have been avoided. The temperature of the bath is -2
It is suitable that it is in the range of 5C to 28C. "However, although there are many examples, the coagulation bath temperature is 0 to 27C, and there are no examples where the temperature is less than 0. In the publication,
``About the temperature of the bath...
・・・・・・・・・・・・Preferably below room temperature, up to around the freezing point. ”, and all Examples were carried out at a coagulation bath temperature of 5C.

The shape of the coagulation bath is not particularly limited. however.

In industrial production, from the viewpoint of increasing the spinning speed to a high level, it is preferable to use a so-called v-shaped coagulation bath as shown in FIG. 3 of JP-A-55-122012.

The dope stream extruded into the coagulation bath undergoes coagulation in the coagulation bath, and then the coagulated thread is removed from the coagulation bath by at least 1.
It is necessary to draw out the draft at a speed of 1 force. Here, the draft is the value obtained by dividing the linear velocity of the coagulated filament when it is drawn out from the coagulation bath by the linear velocity of the dope passing through the spinneret. If the draft is less than 1.5, PPTA
The molecular chains are often poorly oriented, resulting in fibers with low strength and Young's modulus. Brat is preferably 2.0
That's all.

The coagulated filament drawn out from the coagulation bath needs to be washed with water. It is carried out in one or more stages of water washing, and
In order to do this efficiently, it may be combined with an alkaline aqueous solution such as caustic soda. It is preferable to extract and remove as much of the solvent as possible by washing with water. For example, when sulfuric acid is used as the solvent, it is preferable to reduce the residual amount to about 1% by weight or less. The method of washing with water is also not particularly limited, and may be performed using known techniques, for example,
A method of running water in a water bath, a method of spraying water on a rotating roller, a method of washing with water while it is wrapped around a bobbin or cloth,
The method may be selected from methods such as depositing the material on a net and sprinkling water on it, or a combination of these methods. Among these, the method of washing with water on a net is recommended from the viewpoint of improving the fatigue resistance of the fibers obtained, and among them, JP-A-55-1
In terms of dimensional stability and fatigue resistance of the fibers, it is most preferable to perform washing with water, steam treatment, and drying on the internet under the specific conditions disclosed in Japanese Patent Publication No. 22011 and Japanese Patent Application Laid-open No. 122012/1984. .

The washed fibers are treated with oil, etc., if necessary.
It is made into a product yarn by one of the following methods: (1) dried as it is, (2) dried and then heat treated, and (3) washed with water and heat treated. During this time, as described above, steam treatment or the like may be added if necessary.

Drying is performed using a known technique. Usually, the heating is carried out at room temperature or higher, preferably at 100°C or higher, for a period of time such that the moisture content of the fibers becomes several centimeters or lower. The method may be arbitrary, such as depositing it on a net, wrapping it around a bobbin or a whole, running it on a hot roll, etc. The reaction may be performed in two or more stages at the same or different temperatures or by the same or different methods.

Strictly speaking, drying and heat treatment cannot be differentiated, but in the present invention, drying refers to the act of applying temperature under no tension or low tension for the sole purpose of reducing the moisture in the fibers. Heat treatment is the act of applying temperature under tension for the purpose of significantly changing the elongation and Young's modulus of a material. Generally, in the present invention, the fibers produced according to claim 3, i.e., the dry fibers, have high elongation and are suitable for applications such as tire cords. On the other hand, the fibers produced by the method according to claim 4, that is, the fibers that are washed with water after drying or without drying and then directly heat treated, have a high Young's modulus and are effective in reinforcing plastics. The pressure is suitable.

Incidentally, regardless of the presence or absence of heat treatment, the PPTA fiber produced according to the method of the present invention, that is, the method of claim 3 or 4, can be manufactured according to claim 1.
The requirements listed in the section are met.

In the method of the invention, the heat treatment is at least 0.2r/
It needs to be done at 200-550°C under stress. This is because heat treatment that satisfies these conditions yields PPTA fibers with an extremely high Young's modulus, making them useful for reinforcing plastics and the like. The temperature is preferably 250-450°C. An appropriate heat treatment time depends on the temperature, but is usually selected between 0.1 seconds and 10 minutes. The atmosphere in which the heat treatment is performed may be air, but preferably inert nitrogen or argon.

In addition to the characteristics of conventional PPTA fibers such as high strength and high Young's modulus, the fibers of the present invention are expected to have characteristics such as high knot strength and resistance to fibrillation, and are also expected to have excellent buckling properties. Utilizing these properties, it is useful as a reinforcing material for rubber such as tire cords and various belts, and as a reinforcing material for plastics. When the fibers of the present invention are used to reinforce these rubbers and plastics, they are usually used in the form of multifilaments; however, the fibers of the present invention are not limited thereto, and include monofilaments, roving yarns, It can also be used in the form of cloth, chopped strands, etc., as a reinforcing material for ropes, woven fabrics, plastics, metals, cement, ceramics, etc., and as cotton.

Example 1 and Comparative Example 1 A logarithmic viscosity of 5.80 PPTA was obtained according to the reference example of JP-A-55-122012.

PPTA Gold was dissolved in 99.6% sulfuric acid at 75° C. to a polymer concentration of 18% by weight, and defoamed under reduced pressure for about 2 hours. While filtering the dope kept at 75-80℃,
．． It was extruded through a spinneret having 100 pores with a diameter of
% by weight aqueous sulfuric acid solution.

The coagulation bath temperature and draft were varied. The coagulation bath, water washing, and drying steps were performed using the apparatus and method conditions of Example 1 of JP-A-55-122012 (that is, a steam treatment step was added between the water washing step and the drying step).
, PPTA fibers were obtained.

Table 1 lists the varying conditions and properties of the obtained fibers.
Shown below. The strength, elongation, and Young's modulus of the fiber are the values measured for the multifilament, and the knot strength is the value measured by tying one filament into a knot and performing a tensile test. Observation of the striped pattern was carried out by setting the polarizing microscope at or near crossed Nicols, placing the PPTA fiber soaked in the immersion liquid at an angle of approximately 45° to the polarization plane of the polarizer, and using a magnification of 400x. Those in which a dense striped pattern in the direction perpendicular to the fiber length direction as shown in FIG. In addition, the crystal structure has a scattering intensity curve on the equator line in X-ray diffraction of the fiber of 20 = 16 ~ 506
K, 2θ-, 21° as shown in Figure 2 (a)
Tube crystal structure “I”, which shows a busy diffraction peak, (
As shown in b), those exhibiting a diffraction peak at 20ζ18° are listed in Table 2 as crystal structure rIIJ. In addition, 20
Those exhibiting diffraction peaks at both −21° and 20° and 18° are described as “mixture of ■ and ■.”

The fibers of the invention (Examples 1-A-E) are considerably superior in knot strength compared to the fibers based on the prior art (Comparative Examples 1-a-b). Further, since the draft during spinning is too small, the fibers other than the present invention (Comparative Example 1-C), which have a low fiber density, are considerably low in both strength and knot strength.

When the fibers were cut with a safety razor blade, the fibers of Comparative Example 1-a%b cracked and fibrillated near the cut portion, whereas the fibers of Example 1-A-E #1! Observation with an optical microscope revealed that the amount of fibers was relatively small.

Example 2 The PPTA fiber obtained in Example 1-E was heat treated.

The heat treatment was performed while the fibers were run for about 5 seconds in a cylindrical heating furnace in which nitrogen was flowed. Tension was applied by adjusting the ratio of the speed of row 2 on the fiber feeding side to that on the winding side.

The heat treatment conditions and results (structural characteristics and physical properties of the fibers) are shown in Table 2. Note that no striped pattern was observed for any of the fibers.
The crystal was of type ■.

Example 3 PPTA with a logarithmic viscosity of 6.3 and 99. Ofy's sulfuric acid was extruded from a spinneret with a polymer concentration of 19% by weight through a spinneret with 50 holes with a diameter of 0.08111, and after passing through a 15cm air layer, (A) 20% by weight at -10°C. The coagulation bath was introduced into a funnel-shaped coagulation bath filled with an aqueous sulfuric acid solution and (B) a 45% by weight aqueous sulfuric acid solution at −35° C., and was rolled up with a draft of 5.5. The coagulated thread wound around the bobbin was immersed in a 0.1 titanium soda aqueous solution for about 1 hour, and then washed day and night with ion-exchanged water. Next, it was dried overnight in a hot air dryer at 120° C. while being wrapped around a bobbin. In addition, some of the fibers obtained by spinning under the conditions (5) are
Immediately after washing with water, it was heat treated at 400° C. and 0.8 r/d.

The properties of the obtained fibers were as follows.

Fiber obtained by spinning under prison conditions; strength: 2 sy/ds elongation: 4.
9chi, Young's modulus 4 B 0 r/d, knot strength 5.3!
/ / d, no stripes even when viewed with a polarizing microscope, density 1
．． 44 y/CC, orientation angle 21°, "mixed I-type and ■-type" crystal structure.

Fiber obtained by spinning under (B) conditions; strength 21 f/d, elongation 5.1%, Young's modulus 440 f/d, knot strength 5.6 y
/d, no striped pattern even when viewed with a polarizing microscope, density 1.44
f/QC, orientation angle 25°, ■-type crystal structure.

(Fiber spun under At conditions, washed with water, and heat treated; strength 24
r/a, elongation 2.4%, Young's modulus 950 f? /
d% Nodule intensity 4.7 f / d % No stripes under polarized light microscope, density 1,457/CC, orientation angle 11°
, “mixture of type I and type ■” crystal structure.

Example 4 A dope with a polymer concentration of 20.4% by weight was prepared from PPTA with a logarithmic viscosity of 6.9 and 99.8% sulfuric acid, and a spinneret heated to about 85° C.
It was extruded from the coagulation bath at a draft of 6.5, and was then wound around a bobbin. The solvent was removed by washing with water for about 2 days and nights, and then air-dried.

The obtained fiber has a strength of 19? /d, elongation 4.8 inches, Young's modulus 510ff/dx knot strength s, o7. /a, no striped pattern observed by polarizing microscope, density 1.44y/c
c% orientation angle was 20°.

Example 5 and Comparative Example 2 PPTA with a logarithmic viscosity of 5.5 was mixed with 97.0 sulfuric acid and P2O
Dopes with various polymer concentrations were prepared by dissolving Pt0a in a mixture of 5 (Pt0a: 4% by weight based on sulfuric acid). Spinning was carried out under almost the same conditions as in Example 1-E (draft depth changed to 0)
It was done. Table 3 shows the properties of the obtained fibers.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of a striped pattern observed when a poly(p-phenylene terephthalamide) fiber produced using a conventional technique is observed using a fully polarizing microscope. A diffraction intensity curve on the equatorial line in X-ray diffraction is shown. Procedural auxiliary device August 6, 1980, Patent Office Commissioner Kazuo Wakasugi, Indication Patent Application No. 57-103891, Title of Invention: Poly(p-phenylene terephthalamide) fiber with a new structure and amendment to its manufacturing process. Relationship with Patent Applicant (003) Asahi Kasei Industries Co., Ltd. Agent, Toranomon Sangyo Building 5th Floor 6, 2-29 Toranomon-chome, Minato-ku, Tokyo Contents of the Amendment The statement in the specification is amended as follows: 111. "Agglomerated structure" on page 2, line 19 is corrected to "novel agglomerated structure." (21, [Pre c, J on page 3, line 15 is corrected to [Proc, J.
and correct it. (4), page 6, lines 6-7, insert the following statement next to "It can be seen." ``For example, Simens et al. published the observation results when the Keplerian fiber was placed in the same direction as the polarization plane of the polarizer with a polarizing microscope in the crossed Nicol state (J, Polym, Set
, Polym, Phys, Vol. 18, p. 871 (1980)]. ” (5), “Phyo, j” on page 6, line 8 is corrected as “Phys, j.” (6), “Shishyo” on page 6, line 9 is corrected as “proposal”. Correct "It's okay to stay." to "It means it's okay to stay." (8), Correct “1.41 Yoshi” on page 9, line 19 to r 1.41 F/bias 3, button, (9), “Striped pattern is” on page 11, line 4. ``The striped pattern seen in fibers produced using conventional methods'' is corrected. aα, page 11, lines 5-7, “Using a polarizing microscope...
When observed in ...... "Using one or both of the polarizer and analyzer of the polarizing microscope, we made sure that the polarization plane of the polarizer and analyzer did not match the fiber length direction (#lI fiber length direction and polarization plane were 30
~90° is preferred. )," aD1, page 12, line 2, "means." is corrected as follows. "It doesn't make any sense, but depending on the polarizing microscope observation method, it may look like a spiral with a slight inclination from the vertical direction." αTsu corrected "2θ chi 23°" on page 13, line 15 to "20t21°" do. Q3), "ηinh≦4.0" on page 14, line 2 is corrected to "ηinh≧4.0", (14), 14th jj, 15th line t: D "Intensity decrease" is changed to "Intensity decrease is "Less," he corrected. a! 9, page 15, line 4, "PPTA is dope" is corrected to "l'-PPTA is generally dope." aυ, page 18, line 2, insert the following statement next to "Aqueous sulfuric acid solution." This is because "obtained" is separated from "aqueous sodium sulfate solution, potassium sulfate aqueous solution, caustic acid aqueous solution, caustic potash aqueous solution," aη, page 18, line 19. ” he corrected. Cod, "Brat" on page 20, line 16 is corrected to "draft." In line 7 of page 21, "preferable. Washing with water" is changed to "preferable. Washing with water."
and correct it. Kan, page 21, line 9, ``rotating roller'' is corrected to ``rotating roller on which a threaded material is running.'' (21), “Reinforcement, etc.” in line 6 of page 25 is corrected to “for reinforcement, etc.” @, page 24, 1
Correct "Orifu," in line 3 to "Orifu ya." (c) On page 26, lines 1 and 2, ``The polarizing microscope is set at or near crossed Nicols'' is corrected to ``The polarizing microscope is used without an analyzer, only with a polarizer.'' @, on page 27, line 5, amend "to a lesser extent" to "to a lesser extent." (c) In Table 1 on page 28, the density unit “'I/
(: G is corrected as "1/Sono 3". (20, in Table 1 on page 28, "orientation angle" is corrected as "crystal orientation angle", (5), in Table 2 on page 60 , unit of density “1/c
c” is corrected to “1/crIL3”. (c) In Table 2 on page 30, "orientation angle" is corrected to "crystal orientation angle." Kan, "Immerse," on page 31, line 10, is corrected to "immerse." (7), "y /ccs orientation angle" on page 51, line 19 is corrected to "7/Sono 3, crystal orientation angle". 0υ, page 32, line 4, change "? /cc, orientation angle" to "1/en 3, crystal orientation angle"
and correct it. cla, No. 323 (Correct "S'/cc, orientation angle" in line 8 to "rr/crystal orientation angle for river 3", (c), page 33, line 2, ff/cc, orientation angle" is corrected to "27 Sono 3, crystal orientation angle". (B) In Table 3 on page 34, the unit of density rf/c
Correct cJ to "1/certain 3". (To), in Table 5 on page 34, "orientation angle" is corrected to "crystal orientation angle".

Claims (1)

[Scope of Claims] (11) A poly(p-phenylene terephthalamide) fiber having a density of at least 1,4197 m'' and a crystal orientation angle of 60° or less, and which has a direction perpendicular to the fiber length direction as observed by polarizing microscopy. A poly(p-phenylene terephthalamide) fiber characterized in that no dense striped pattern is observed. (2) A patent claim characterized in that it partially or entirely has a ■-type crystal structure. The poly(p-phenylene terephthalamide) fiber according to item 1. (31!/(p-phenylene terephthalamide)) is dissolved in sulfuric acid or a solvent mainly composed of sulfuric acid to a polymer concentration of at least 15% by weight. The dope is passed through a spinneret into a non-coagulable fluid and then extruded into a coagulation bath maintained at below 15 C, the coagulated filament being withdrawn from the coagulation bath at a speed such that a draft of at least 1.5 is applied; Poly(p-phenylene tele 7j) with water washing and drying as %t
1 Ruamide) Fiber manufacturing method. (4) A dope of poly(p-phenylene terephthalamide) dissolved in a solvent mainly composed of total sulfuric acid or L sulfuric acid to a polymer concentration of at least 15% by weight is poured into a non-coagulable fluid from a spinneret. The coagulated filament is then extruded into a coagulation bath maintained at less than 15 C, and the coagulated filament is drawn out from the coagulation bath at a rate of at least 1.5 draft, and after washing with water,
200~ with a tension of at least 0.2 f/d
A method for producing poly(p-phenylene terephthalamide) fiber, characterized by heat treatment at 550C.