JPS6197355A - Production of polyamide fiber or film having high young's modulus - Google Patents

Abstract

PURPOSE:To obtain an arom. polyamide fiber or film having high Young's modulus, by preparing a dope comprising a polyamide, an alkali metal or alka line earth metal halide, an amide solvent and sulfuric acid and molding the dope in a wet process. CONSTITUTION:An optically anisotropic dope comprising a polyamide composed of repeating units selected from among those of formulas I, II and III, 0.1-5wt% (based on the quantity of polyamide) alkali metal or alkaline earth metal halide, 0.1-5wt% (based on the quantity of polyamide) amide solvent (C) and 98-100wt% sulfuric acid (D) is prepd. and molded in a wet process to obtain the desired polyamide fiber or film. When the polymer contains both repeating units of formulas I and II, they are present in an equimolar amounts. In the formulas, R, R', R' are each a bivalent group; n is 0, 1; at least 95mol% of R, R', R' consists of one rigid group contg. a chain extending bond or two or more rigid groups which are bonded to each other through a chain extending group or an azo or azoxy group.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a process for producing aromatic polyamide fibers or films with improved mechanical properties. More specifically, it relates to a method for producing aromatic polyamide fibers or films with mechanical properties, particularly high Young's modulus, from an optically anisotropic dope containing an alkali metal or alkaline earth metal halide and an amide solvent. It is.

BACKGROUND OF THE INVENTION Aromatic polyamides are already known polymers, and it is also known that fibers obtained from them have excellent heat resistance and mechanical properties because they have a rigid molecular structure. According to Japanese Patent Publication No. 47-39458, an aromatic polyamide-based polymer having a limited inherent viscosity was spun by aerial discharge wet spinning using sulfuric acid as a solvent and a dope containing a specific polymer. It has been described that fibers with exceptionally high tensile strength and Young's modulus can be obtained as is, ie without drawing or heat treatment.

However, although these aromatic polyamide fibers have an exceptionally high Young's modulus as they are spun, they cannot be used as advanced composite reinforcing materials for aircraft, space materials, etc., where particularly toughness is required. Compared to ceramics, graphite, boron, etc., Young's modulus is still insufficient, so it cannot be used as is. To this end, with the aim of obtaining improved high Young's modulus fibers useful as reinforced plastic composite materials, a method has been proposed in which the as-spun fibers are heat treated under tension to further improve the Young's modulus. It is disclosed in 1983-43419.

However, in this heat treatment method, in order to obtain fibers for use in advanced composite materials, the resulting fibers are once spun and subjected to heat treatment again, resulting in an extremely low productivity. This had the major disadvantage of causing a decrease in viscosity and tensile strength.

Further, a method for obtaining local Young's modulus fibers of para-oriented aromatic polyamide is disclosed in JP-A-52-12325 and JP-A-52-12326, and according to these publications, air discharge It is said that fibers with high strength and high Young's modulus can be obtained by pre-stretching the coagulated yarn as wet-spun and then heat-treating it at a temperature of 300° C. or higher.

According to the above-mentioned method, a fiber having a high Young's modulus of 1000 f/d or more can be obtained, but two steps of preliminary stretching and heat treatment are required to increase the Young's modulus, and the apparatus becomes complicated. Furthermore, since the heat treatment is carried out at a high temperature of 300° C. or higher, there is a serious drawback in that the amount of energy consumed is large.

It is generally known that the Young's modulus of fibers corresponds to the crystal orientation measured by X-ray diffraction, etc., and treatments such as hot stretching are effective as methods to improve the crystal orientation. Something has been proposed. Similarly, for fibers made of aromatic polyamide, it is disclosed that the method of stretching the fibers obtained by spinning them in a heated atmosphere as described above is extremely effective in improving the Young's modulus. On the other hand, in the spinning process, increasing the tension at the time of take-off has the same effect of improving crystal orientation as in the drawing process, but in general, the increase in the tension at the time of take-off causes destruction of the fiber structure and It has been said that the tensile strength usually decreases significantly, especially in wet spinning methods in which a polymer solution is introduced into a coagulation bath.

On the other hand, the solubility of para-oriented aromatic polyamides is extremely poor, and the only good solvent system known is concentrated sulfuric acid or its similar compounds11.
No. 39458 discloses at least 98-concentration sulfuric acid and chlorosulfuric acid, fluorosulfuric acid and mixtures of these acids;
Alternatively, if necessary, these acids can be added to hydrofluoric acid, halogenated alkyl sulfonic acid, halogenated aromatic sulfonic acid, halogenated acetic acid, halogenated lower alkyl alcohol, and halogenated ketone or aldehyde, trifluoromethane. A mixture of sulfonic acid, sulfone, chlorinated phenol, and nitrope/ze/ as additives containing up to about 30% of the total weight of the solvent and additives is used as a solvent to form an optically different material from para-oriented aromatic polyamide. A directional dope is made and fibers or films are obtained from the dope. In order to obtain molded products such as fibers or fillets with excellent mechanical properties from such sulfuric acid dope, a dope in which a highly polymerized, highly oriented aromatic polyamide is dissolved in a high concentration is actually required. , the moldability decreased as the dope concentration increased.

On the other hand, as a method to improve solubility and moldability, it was proposed to create a dope composition consisting of a loosely oriented aromatic polyamide, sulfuric acid, and a metal heptadide (Japanese Patent Laid-Open No. 50-4
However, with such dopes, the decomposition of the unevenly oriented aromatic polyamide is promoted as well as the solubility, and the degree of monopolymerization is lowered, so that the dope cannot exhibit sufficient effects. Ta.

Problems to be Solved by the Invention In the process of researching the formability of highly concentrated sulfuric acid dope for individually oriented aromatic polyamide, the present inventors unexpectedly found that by adding conventional It was predicted that solubility would decrease.

It was discovered that by adding a specific amount of both a metal halide and an amide solvent, the solubility was not reduced and the fluidity and moldability were excellent, and the fibers obtained from the dope were They also discovered that the orientation of the film was extremely superior to that obtained from the conventionally known Dogue, and as a result of further improvement research, they found that excessive stretching, heat treatment, or spinning after spinning or film formation Alternatively, they discovered that polyamide fibers or films with extremely excellent orientation and high Young's modulus could be efficiently produced by simply spinning or forming a film without applying a high degree of tension during film formation, and completed the method of the present invention. This is what I did.

The constitution of the invention, that is, the present invention, consists of units of the following formula: l
may be the same or different and represent a divalent group, n
is 'O or an integer 1, and all groups R, R' in the polymer
and at least about 95 moles of R" consist of one hard group with a chain linkage or a series of such hard groups connected to each other by a chain linkage either directly or through an azo or azoxy group.) In producing a fiber or film consisting of a polyamide consisting essentially of repeating units selected from the group consisting of: the polyamide, an alkali metal or alkaline earth of 0.1% to 5% by weight based on the polyamide; An optically anisotropic dope is prepared from a metal halide, an amide solvent in an amount of 0.1 to 5 by weight relative to the polyamide, and sulfuric acid at a concentration of 98 to Zoo weight %, and the dope This is a method for producing polyamide fibers or films with a high Young's modulus, which is characterized by wet molding.

Preferred Embodiments The polyamide used in the present invention has a group of the following formula (in the above formula,
The units l and I, when present in the polymer, are present in substantially equimolar amounts, the groups RSR' and R# may be the same or different and represent divalent groups, n is 0 or an integer, and at least about 95 moles of all groups RSR' and R'' in the polymer are one rigid group with extended chain bonds or a series of such groups directly bonded to each other by extended chain bonds. consists essentially of repeating units selected from the group consisting of hard groups.

Furthermore, the azo group -N-N- and the azoxy group ↑ -N-N- can serve to link two hard cyclic groups. A substantial portion of the polymer thus consists of polyamide units (including polyoxamide units where n is 00) giving a rigid chain.

The term "hard group" herein refers to (a) cyclic groups: monocyclic or fused polycyclic aromatic carbocycles or heterocycles;
-(2,2,2)-bicyclooctylene, and (b)
Linear unsaturated group: means vinylene-〇H=CH- and ethenylene-〇=C-. It should be noted that monomers containing amino groups directly bonded to linear unsaturated groups are not stable and therefore vinylene or ethenylene cannot serve as part of the group R'' bonded to R' or -N-. It is to be understood that the term "extended chain bond" refers to substantially coaxial (e.g.
, and a bond that extends the molecular chain of the group facing in the opposite direction (whether or not the molecular chain is extended is determined by actually measuring the bond angle). These polymer structures are further characterized by the formation of anisotropic or liquid, crystalline phases when mixed with certain strong protic acid solvents.

This will be explained in detail later.

Suitable groups with extended chain bonds, which are suitable for RSR' and R'', include trans-1,4-cyclohexyl and trans-vinylene, ethynylene, azo or azoxy-linked 1,4-phenylene radicals. Furthermore, R is trans-vinylene, ethynylene, trans, trans-1.
The 4-butadienylene radical can also serve as R".

RSR' and R'' may be substituted and/or unsubstituted groups. Substituents, if present, are preferably non-reactive during subsequent processing of the polymer (such as during heat treatment of its molded article). The reactivity of the substituent should be such that it causes branching and crosslinking of the polymer and adversely affects the properties of the dope and/or fiber. Suitable non-reactive substituents include halogen (e.g. chloro, bromo and fluoro), lower alkyl (e.g. methyl, ethyl and isopropyl), methoxy, cyan and nitro groups. Preferably, two (more preferably at most one) suitable substituents of high bulk are present per group. More preferably, groups RSR' and R"020 or less in the polymer are substituted. should be R”.

Preferred types of polymers of the group described above are those in which R and R' are groups 1.
4-phenylene, 4,4'-biphenylene, 2,6-naphthylene, 1,5-su7tyrene, and trans-1,4
-cyclohexylene, where R is further a group 2,5-
selected from pyridylene and trans-vinylene: R“
is 1,4-phenylene: and at least 50 moles of the total of R and R' are completely aromatic (n = 1'). Among the preferred polymers of this type, the most preferred are those in which R is the group 1,4-phenylene, 4,4'-biphenylene, 2,6-naphthylene, 2.
selected from 5-pyridylene, trans-1,4-cyclohexylene, and trans-vinylene: R' is trans-1,4-cyclohexylene, 1,4-phenylene N
and U1*+-yx dilene and 4,4' of less than 50 molti
- selected from mixtures with biphenylene: R" is 1.4
-phenylene: and (a) at least 75 moles of the total of R and R' are completely aromatic; and (
b) at least 75 moles of either R or R' is 1
．． It is a polymer that satisfies the condition that it is 4-phenylene.

The linear condensation polymer chains of the present invention may contain up to about 5 moles (on a molar basis) of groups not in accordance with the above description, such as groups that do not have extended chain bonds or are not rigid.

It should be understood that groups that do not meet these conditions will have different effects on the properties of the as-spun product. That is, hard groups such as m-phenylene/, in which the chain-extending bonds are neither coaxial nor parallel and opposite, and very soft groups such as hexamethylene and decamethylene, are usually used in small amounts, whereas 4 , 4'-bipendylene can be used in higher amounts, exceeding 5%, to produce fibers that still exhibit the unusual properties of the product of the present invention, an excellent combination of substances. A minor portion of the amide units in the linear condensation polymer chain may be replaced, if desired, by other stable non-amide-forming units, such as ester-forming units or urea- or sulfonamide-forming units, although this is not preferred. .

The polymer to be spun may be a homopolymer, a random copolymer, an ordered copolymer or a mixture of homopolymers and/or copolymers. The fibers and films of the present invention may also incorporate conventional additives such as dyes, growth agents, deglazing agents, UV stabilizers, antioxidants, and the like.

Suitable polyamides include poly(p-phenylene terephthalamide); poly(p-phenylene p,p'-biphenyldicarpoxamide); poly(p-phenylene 1.
5-naphthalenedicarpoxamide); poly(trans,
trans-4,4'-dodecahydrobiphenylene terephthalamide); poly(trans-1,4-cinnamamide); poly(p-phenylene 4,3-quinolinedicarboxamide); poly(1,4-(2,2, 2)-picyclooctylene terphthalamide); copoly(p-phenylene 4,4'-azoxybenzenedicarboxamide/tele7thalamide); poly(p-phenylene 4,4'-trans-stilbenzylcarboxamide); poly(p
-phenylene acetylene carboxamide).

Specifically, the alkali metal or alkaline earth metal halides used in the present invention include heptafluorides of lithium, sodium, potassium rubidium, cesium, heptaranthicum, beryllium, magnesium, calcium, strontium, barium, and radium. , chloride, bromide, and iodide. Among these, halides of lithium, magnesium, and calcium, particularly chlorides, are preferably used.

In the DOG of the present invention, these alkali metal or alkaline earth metal halides are used together with the amide solvent described below to achieve the excellent moldability of the present invention.
It forms a dope that provides highly oriented fibers or films, and the amount thereof is selected within the range of 0.1% by weight or more and 5% by weight or less based on the polyamide. The reason why this range is selected is that below 0.1 Kin, fibers or films with a high Young's modulus M with sufficient formability and high orientation cannot be obtained, and when above 5 Kin, the polyamide causing a decrease in the solubility of
This is because it is not a stable molding dope.

A preferable example of the alkali metal or alkaline earth metal halide is 0.2* to 4 weight, more preferably 0.5 M to 31 weight.

In this range, the dope of the present invention has excellent moldability and becomes a highly effective molding dope that provides highly oriented fibers or films. Further, within this range, these alkali metal or alkaline earth metal halides may be used alone or in a mixture of two or more.

In addition, in the dope of the present invention, these alkali metal or alkaline earth metal halides are
It is thought that some or all of it reacts with sulfuric acid, which is one of the components forming the dope, to form hydrogen halide and alkali metal or alkaline earth metal sulfates, but with the current analytical technology, However, it must be understood that this cannot be quantitatively understood.

The amide solvent used in the present invention refers to a linear or cyclic N-substituted amide of an aliphatic carboxylic acid, and specifically,
Examples include N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, hexamethylphosphorotriamide, 2,5-dimethy//imidazolidinone, nato-2methylurea, etc. 5, especially N-methyl-2
-Pyrrolidone is preferred in the present invention.

In the dope of the present invention, these amide solvents are preferably selected in a range of 0.1% by weight or more and 5% by weight or less based on the polyamide. That is, below 0.1 weight,
Although there are no particular problems in terms of moldability, the initial purpose of the dope, which can provide highly oriented fibers or films, cannot be fully achieved. On the other hand, if it is more than 5 mls, the seedling stability of the polyamide decreases and the viscosity of the dope increases rapidly, which is not preferable because it significantly reduces the moldability. If too much amide solvent is contained, the polyamide loses its solubility and eventually precipitates. A suitable amount of the amide solvent is 0.2M to 5% by weight, more preferably 4'M to 4% by weight, based on the polyamide.

In this range, the dope of the present invention has excellent moldability, particularly dope stretchability, and provides a fiber or film with high Young's modulus and high orientation. Within this range, the amide solvents may be used alone or as a mixture of two or more.

The sulfuric acid used in the present invention needs to have a blood volume of 98 or more and 100% by weight or less. If the concentration of sulfuric acid is less than 98% by weight, the dissolving power for the polyamide used will decrease, making it difficult to obtain a high-concentration dogu, which is important for molding. 1o
This is because if the amount of sulfuric acid exceeds the amount of polyamide, the trivalent sulfur itself acts as a non-solvent for the polyamide, thereby reducing the solubility.

The reason why the dope in the present invention maintains high boiling properties and gives excellent formability, that is, stringability, and gives high orientation when made into fibers or films is estimated as follows. That is, in the dope of the present invention, the alkali metal or alkaline earth metal halide exists in a highly dissociated state, and at the same time, together with the amide solvent ionized in sulfuric acid, the amide of the polyamide It is thought that the bonding strength between amide bonds is weakened by the orientation of the amide bonds.As a result, compared to conventional sulfuric acid-based dopes, it becomes possible to fluidize with less stress, especially during molding, that is, during flow and stretching. Therefore, in the dope used in the method of the present invention, either an alkali metal or alkaline earth metal halide, or an amide solvent is used. However, the effect cannot be fully exerted, and high moldability and excellent orientation can only be achieved by including both.

At this time, it is expected that the ratio of the alkali metal or alkaline earth metal halide and the amide solvent will affect the characteristics of the dope used in the present invention, but the inventors' According to the results of detailed research,
The range of the combination of both amounts for the polyamide described above does not have any particular influence, and the effects of the present invention can be fully exhibited.

In the present invention, it is important that the dope has optical anisotropy. Here, whether or not the dope has optical anisotropy can be measured, for example, by the method described in Japanese Patent Publication No. 50-8474. The fact that the dope has optical anisotropy is considered to correspond to the fact that it forms a liquid crystal.The reason why the dope of the present invention should have optical anisotropy is as follows. should be understood. In other words, it is difficult to think that the fact that the dope has optical anisotropy itself is directly related to the superior mechanical properties of the molded article (fiber or film); rather, the high polyamide concentration in the dope is important. Therefore, it should be considered that such a high polyamide concentration produces optical anisotropy in the doped state and excellent mechanical properties in the molded product. It is important as an index showing the substitute characteristics of .

The range of the polyamide concentration that exhibits optical anisotropy varies slightly depending on the degree of polymerization (intrinsic viscosity) of the polyamide, the temperature of the dope, the sulfuric acid concentration, the amount of alkali metal or alkaline earth metal halide, amide solvent, etc. However, as will be explained in detail later, it is about 10% by weight or more.

The intrinsic viscosity of the polyamide used in the present invention is not particularly limited, but is usually 1.0 or more lO0 as measured by the method described below.
θ or less, preferably 3', 0 or more and 7.0 or less is appropriate. The polyamide concentration of the dope may be any concentration that forms an optically anisotropic dope; specifically, the total solution (sulfuric acid, alkali metal or alkaline earth metal halide, amide solvent, and polyamide) Defined in terms of weight percent, it is suitable to be about 10 to 25 weight %, preferably 14 to 20 weight %.

In preparing the dope used in the method of the present invention, the alkali metal or alkaline earth metal halide and amide solvent may be added at any time when the polyamide is being dissolved, or after the polyamide has been mixed, swollen, or dissolved in sulfuric acid. and then add both at their respective stages, or dissolve them in sulfuric acid in advance and then add the polyamide, or add the halide and/or amide solvent in advance. After adhering to polyamide,
A method such as dissolving in sulfuric acid is used. When dissolving the polyamide in the above solvent, hydrogen fluoride, hydrogen chloride, fluorosulfuric acid, chlorosulfuric acid, antimony trifluoride, antimony trifluoride, boron trifluoride, phosphorus trifluoride, etc. may be used as a dissolution aid. You can also use more than one of them.

Fibers or films produced from the dope of the present invention include:
Known additives such as antioxidants, heat stabilizers, ultraviolet absorbers, colorants, flame retardants, matting agents, etc. may be added according to known formulations.

In order to produce fibers from the dope in the method of the present invention, a technique similar to the conventional wet spinning method can be used.The above-mentioned dope is degassed and filtered as necessary, and then passed directly into the coagulation medium through Oliice. or once passed through a non-coagulating medium such as air, extruding into a coagulating medium and solidifying into fibers in the coagulating medium.Water is preferably used as the coagulating medium, but methyl alcohol , monohydric or polyhydric alcohols such as ethylene glycol, glycerin, and ingropanol, mixtures of water and the above alcohols, acids such as sulfuric acid, alkalis such as ammonium hydroxide, and various salts such as calcium chloride are used. During this wet spinning, the temperature of the dope or coagulation medium is
Although there are no particular limitations, it is generally desirable that the temperature be in the range of -10 to 100°C.

In a preferred embodiment of the use of the dope of the present invention, the dope is spun into a non-coagulating atmosphere and the spun fiber stream is then solidified into fibers in a coagulating medium. In addition to this, it is desirable to form the fibers by a so-called downward tension spinning method, in which a coagulating medium is allowed to flow down in the spinning direction of the fibers, and tension is applied to the fiber stream by friction generated between the coagulating medium and the fiber stream.

Further, if necessary, treatments such as stretching can be performed at each stage of spinning.

As the non-coagulating medium, a gas such as air or nitrogen or a liquid immiscible with the dope such as a hydrocarbon liquid is used, and as the coagulating medium, those exemplified above are used. The fibers wound up at an appropriate spinning speed are treated with a cleaning solution such as water or a chemical solution, and then dried with air at 90 to 15 lt for an appropriate period of time.

Depending on the case, heat treatment at an appropriate temperature can also be performed.

Films can also be formed from the dope of the present invention in the same manner as fibers.

Effects of the present invention According to the method of the present invention, fibers or films having a high Young's modulus can be easily obtained without drawing, high-temperature heat treatment, etc., and the excellent fluidity and moldability of the dope make it possible to As a result of being able to stably stretch the fibrous or film-like dope extruded from a die or the like at a high ratio, it is possible to obtain high-quality fibers or films with extremely small irregularities in thickness or thickness.

In addition, the fibers or films produced by the method of the present invention have high strength and Young's modulus, as well as good heat resistance.Because of these characteristics, the fibers are suitable for many industrial applications.
For example, it is useful as a reinforcing material for rubber products such as tire cords, rubber belts, and hoses, or as a fiber reinforcing material for various fiber-reinforced plastics, or as industrial fibers such as ropes, ν cloth, and various covers, and as clothing fibers such as sewing thread. Moreover, the film is suitably used for electrical insulating films, magnetic tapes (computer tapes, video tapes, cassette tapes, etc.), microfilms, motion picture films, transparent films, packaging strings, and the like.

Hereinafter, the present invention will be described in detail with reference to Examples and comparative examples thereof.

In addition, the intrinsic viscosity (η1nh) used in the examples is:
It is expressed by the following formula.

d1nh=m(ηr)/C In the above formula, C is the concentration of the polymer solution (solvent 100 - medium coalescence or fiber or film 0.5 f), and ηr
(Relative viscosity) is determined by dividing the flow time of the polymer solution, measured at 35° C. in a capillary viscosity tube, by the flow time of the pure solvent. The solvent here is concentrated sulfuric acid (95-9
8% by weight) is used.

In addition, in the examples, poly(p-phenylene terephthalamide) (
(hereinafter abbreviated as PPTA), the embodiments of the present invention and the effects thereof are not limited to the examples.

<Measurement method of strength and elongation properties of fibers and films> Measurement of strength, elongation and Young's modulus of fiber threads is in accordance with JIS standards.
Prior to measurement, the yarn that had been twisted 98 times per 10 strands was tested using a constant speed elongation strength and elongation tester at 20 grip lengths.
Draw a load-elongation rate curve at a tensile rate of 50%/min,
It was read or calculated from that, and the number of measurements was 20.
Expressed as the average value.

The strength, elongation and Young's modulus of the film are measured using the width Row
A test piece with a length of 50 m was cut out, a load-elongation rate curve was drawn using a constant-speed elongation strength/elongation tester at a speed of 100%/min, and the average value of 10 measurements calculated from the curve was expressed.

Measuring method of orientation angle (OA)> The orientation angle (OA) of fibers can be measured using, for example, an X-ray generator (RU-200PL) manufactured by Rigaku Corporation or a fiber measuring device (FS-
3), carried out using a goniometer (SG-9R) and a scintillation counter. For measurement, CuKa (λ=1.5418 A
).

The fibers of the invention are generally characterized by having two major reflections on the equator. Orientation angle measurement is performed using high angle 2θ
Use reflections with . The 20 reflections used are determined from the equatorial diffraction intensity curve.

The xm generator operates at 40KV 90mA. Attach the fiber sample to the fiber measuring device so that the single yarns are parallel to each other. It is appropriate that the thickness of the sample be approximately 0.5 □. Set the goniometer to the 2θ value determined by preliminary experiments. X-rays are incident perpendicularly to the fiber axes of these fibers arranged in parallel (beam perpendicular transmission method)
. The azimuthal direction is scanned from -30° to +30°, and the diffraction intensity is recorded on recording paper using a scintillation counter. Furthermore, the diffraction intensities at −1800° and +180° are recorded. At this time, the scanning speed is 4°/m, the chart speed is 1.0α/-, and the time constant is 2 or U5s.
ec collimation 1'-1+18φ, receiving slit length and width are both 10.

To determine the orientation angle from the obtained diffraction intensity curve, ±18
Take the average value of the diffraction intensity obtained at 00 and draw a horizontal line. Vertical from the top of the peak to the baseline #i! , and find the midpoint of its height. Draw a horizontal line through the midpoint. The distance between the intersection of this horizontal line and the diffraction intensity curve is measured, and the value obtained by converting this value into an angle (0) is defined as the orientation angle (OA).

Example 1 After adding 99.8% by weight sulfuric acid 25BOf KN-methyl-2-pyrrolidone 12.9f and dissolving with stirring, PPT
Add A(ηinh = 7.9) 624 f,
The temperature was maintained at 70-75°C and the mixture was stirred for about 1.5 hours to dissolve. Then, while maintaining the temperature, powdered anhydrous calcium chloride 12.9 F was added and stirred for about 30 minutes to obtain a glossy optically anisotropic dope. The solution viscosity of this dope is 8400 poise (78°C) fC, and this dope is transferred to a spinning device whose temperature is kept at 75 to 78°C.
After about 2 hours of vacuum degassing, a 0.06 rigφ×50
It is applied to a Hall spinneret and extruded vertically into water at 3°C through an air layer of 10III at various linear discharge speeds.
It was taken out by applying a draft (take-up speed/discharge linear speed) and wound onto a bobbin.

After washing the obtained fibers with the bobbin by immersing them in running water overnight,
It was dried at 0° C. for 2 hours to obtain dry fibers.

Further, 8.8 f of the defoamed dope was stretched on a glass plate kept at 75°C to a thickness of 0 to 25 m, and then poured into water. After drying for a while, a film was obtained.

The results are shown in Table 1.

Margin table below 1 Comparative Example 1 2580 t of 99.8 wt% sulfuric acid was added with PPTA (η1
nh=7.9) 624t was added, the temperature was maintained at 70 to 75°C, and the mixture was stirred and dissolved for about 2 hours to obtain a glossy optically anisotropic dope. The solution viscosity of this dope was 7900 poise (76°C). Example 1 using this dope
Fibers and films were produced using spinning equipment and conditions including long draft measurements. Table 2 shows the results obtained at this time.
Shown below.

From the comparison of Tables 1 and 2, it can be seen that the dope of the present invention (I 1) has a maximum draft, that is, a maximum elongation rate, in which the spinnability is also an important factor, compared to that of the conventional sulfuric acid dope (Table 2). It was demonstrated that the moldability was high at all linear discharge speeds, and that the moldability was excellent. In addition, the orientation of the obtained fibers and films is higher and better than that of fibers and films obtained from conventional sulfuric acid-based dopes.As a result, in terms of physical properties, while maintaining high strength, It was recognized that the fiber and film had extremely excellent Young's modulus.

Margin table below 2 Example 2 2280 tons of 98.5% by weight sulfuric acid was added with PPTA (η1
nh=6.8) 518f was added and stirred for about 1.5 hours while maintaining the temperature at 75°C to obtain a dope (dope marked positive in Table 3; Comparative Example 2). This dope was a dope exhibiting glossy optical anisotropy.

Similarly, dopes were prepared from sulfuric acid and PPTA of the same concentration in the above-described manner, and each dope, KN-methyl-2-pyrrolidone and calcium chloride, was added in the amounts shown in Table 3 and dissolved with stirring.

All of these dopes showed optical anisotropy, but the dope containing only calcium chloride at 5% by weight based on PPTA (mt) and the dope containing only N-methyl-2-pyrrolidone at 6% by weight relative to PPTA
All of the dopes to which heavy ft% was added (No. 6) had poor luster compared to other dopes, and were on the verge of devitrification.

These dopes were spun using the same spinning apparatus and conditions as in Example 1, washed with water, and dried to obtain fibers. These results are shown in Table 3.

The fibers obtained by the method of the present invention all have extremely high orientation and are high Young's modulus fibers, and in order to obtain such high Young's modulus fibers, it is necessary to It was recognized that both compound and amide solvents were required.

Example 3 99.3 weight polysulfuric acid 3444 f, 15.2P N,
After adding and dissolving N-dimethylacetamide, 75
PPTA (η1nh=7.2)75 while keeping the temperature at ℃.
61F was added and dissolved with stirring for about 2 hours. Then, while maintaining this temperature, 7.61 g of anhydrous calcium chloride was added and dissolved with stirring to obtain an optically anisotropic dope (solution viscosity: 396° poise/76° C.).

This dope was transferred to a spinning device whose entire temperature was kept at 75 to 78°C, and after vacuum degassing for about 3 hours, it was passed through a conduit with a built-in filter using a gear pump.
It was extruded from a Hall spinneret at a linear discharge speed of 2 m/min. This dope flow 'if 5° through the air layer
It is guided vertically into water maintained at ℃, and taken out along with the crossbars through a glass tube with an inner diameter of 4 mm and a length of 20 mm installed downward at a depth of 20 m from the surface of the crossbars, passed through Nelson rolls, and then bobbined at a speed of 600 m/minute. I rolled it up. The rolled fibers were then immersed in running water for washing while still wound around the bobbin, and then dried in a hot air dryer at 120°C. After stretching it to a thickness of 0.125 m, it was poured into water, and -
After washing with running water, it was dried in a hot air dryer at 120°C.

The physical properties of the obtained fibers and films are as shown in Table 4.
The fibers and films were excellent in both strength and Young's modulus.

Table 4 Example 4 99.6% sulfuric acid 2590f, PPTA (
Optically anisotropic dope (viscosity 63
7o voids/74°C). This dope was spun and film-formed using the same spinning equipment and conditions as in Example 3 to obtain fibers and films. The physical properties of the fiber and film are shown in Table 5 together with the results of Example 5.

Example 5 2590 t of the same sulfuric acid used in Example 4.

PPTA 608 t, N-methyl-2-pyrrolid 7
12.2f and anhydrous magnesium chloride 12.2f
Then, optically anisotropic dope (viscosity 680
0 poise/74°C). This dope was spun and film-formed using the same spinning equipment and conditions as in Example 3 to obtain fibers and films.

Below margin

Claims (2)

[Claims] (1) Units for the following formulas ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (I), ▲ Mathematical formulas,
Chemical formulas, tables, etc. ▼(II) and ▲Mathematical formulas, chemical formulas, tables, etc. ▼(III) and the groups R, R' and R
″ may be the same or different and represents a divalent group,
n is 0 or an integer 1, and groups R, R' and R in the polymer
At least about 95 mol % of the total amount of `` is composed of one hard group having extended chain bonds or two or more hard groups connected to each other by extended chain bonds directly or through an azo or azoxy group. ) In producing a fiber or film made of a polyamide consisting essentially of repeating units selected from the group consisting of Halides of similar metals, 0 for the polyamide
．． A high Young's modulus characterized in that an optically anisotropic dope is prepared from an amide solvent of 1% by weight or more and 5% by weight or less and sulfuric acid at a concentration of 98% or more and 100% by weight or less, and the dope is wet-molded. Method for producing polyamide fiber or film (2) The alkali metal or alkaline earth metal halide is one or more selected from lithium chloride, magnesium chloride, and calcium chloride, and the amide solvent is N
-Methyl-2-pyrrolidone A method for producing a polyamide fiber or film having a high Young's modulus according to claim 1