GB2505387A - High tensile strength aramids - Google Patents

Abstract

Aramids, which in the undrawn state have high tensile strengths and tensile elongations, and which after drawing have in addition high tensile moduli, are made from units derived from selected 2,2'- disubstituted-4,41-bibenzoic acids, p-phenylenediamine, and terephthalic acid. The aramids are useful for ropes and composites.

Description

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TITLE --

HIGH TENSILE STRENGTH ARM4IDS

FIELD OP INVENTION

Aramid polymers, some of whose fibers and films are drawable, and before or after drawing possess a combination of very high tensile strength and tensile elongation and, after drawing a high modulus, are provided. Also provided is a process for drawing such fibers.

-flCHNICAL ACGROUND It is well known in the art that para-aramid polymers, such as those derived from terephthalic acid (T) nd p-phenylenedianiine (PPD) have a high modulus and relatively high tensile strength compared with conventional fibers. Such polymers are highly crystalline, and can be drawn very little, usually less than about 1%. Drawing and heat treating (annealing) of such polymers may result in large increases in modulus, but virtually no increase in tensile strength. It is desirable to provide polymers which are relatively high in modulus, and drawable (beyond 1%), and whose tensile strength and elongation are significantly increased before or after drawing. Thus, in the present invention, selected substituted 4,4'-bibenzoic acids are used in the present invention to replace specific amounts of T in PPD/T polymers to form drawable aramids.

It is also desirable to provide aramids, which in fiber or film form display outstanding toughness in the undrawn state. Disclosed herein are aramids which have relatively small amounts of 2,2'-disubstituted-4,4'---bibenzoic acid containing units display such properties.

H. W. Schmidt and D. Guo, Makromol. Client., vol. 189, p. 2029-2037 (1988) report the use of 2,2'-dimethyl-4,4'-bibenzoic acid units in an aromatic ent

S

polyester. No mention is made of the use of this compound in an aramid.

U.S. Patents 4,384,107 and 4,461,886 disclose aramids containing either stilbinyl and/or biphenylyl * 5 units. Mong the possible biphenylyl type units are those derived from 2,2 -disubstituted-4, 4 -bibenzoic acid, and specifically mentioned substituents are chloro, bromo, nitro and methyl. No mention is made of * the use of PPD/T units in a random copolymer.

U.S. Patent 4,843,141 discloses polyesteramides containing units derived from 2,2'-disubstituted-4,4'-bibenzoic acid, an aromatic aminophenol, and optionally an aromatic diacid, such as terephthalic acid, and also optionally an aromatic hydroxy acid or amino acid. -Specifically mentioned substituents include chioro, bromo, nitro and methyl. No mention is made of the use of these bibenzoic acids in aramids (as opposed to polyesteramides).

The drawing of incompletely or poorly oriented polymers in general is well known but the drawing of well oriented ararnids is more difficult. Certain aramids that are essentially noncrystalline may be readily drawn. But crystalline, well oriented aramids (such as P?D/T), which have the advantage of having relatively high tensile moduli and strengths are not readily drawable, that is they can normally be drawn only about * 1-2% or less without substantial improvement of tensile strength. Higher amounts of draw woul&be expected. to lead to still better alignment of the polymer chains and hence higher tensile strengths. Thus, it would be desirable to be able to draw aramids, as in the fiber * form, such that the "highlyTM drawn aramid would have improved tensile strength and have substantial crystallinity. S 3

SUMMARY OF THE INVENTION' -

An aramid random copolymer is provided which consists essentially of about 70 to 99 mole percent of units derived from PPD and T ("first units" herein) and S about 30 to 1 mole percent of units derived from 2,2'-disubstituted-4,4'-.bibenzojc acid and PPD ("second units" herein), wherein the 2,2' substituents are chlorine, bromine, nitro and methyl. Some of these polymers, especially in fiber form, may be drawn to give highly oriented crystalline fibers with much improved tensile strength, as well as high tensile modulus at a higher elongation beyond that usually obtained with flD/T polymer.

Accordingly, it is one objective of this invention to provide polymers which are relatively high in modulus, and drawable (beyond 1%), and whose tensile strength and elongition are significantly increased before or after drawing. Thus, selected substituted 4,4'-bibenzoic acids are used to replace specific amounts of T in PPD/T polymers to form drawable aranids.

It is another object of this invention to provide aramids, which in fiber or film form display outstanding toughness in the undrawn state. Aramids which have relatively small amounts of 2,2'-disubstituted-4,4'-bibenzoic acid containing units display such properties.

DETAILS OF TR INVENTION

This invention concerns an aramid-random copolymer consisting essentially of about 70 to 99 mole percent of a first unit of the formula 0 0 H -Hit ii

-N N-C C-

and about 30 to 1 mole percent of a second unit of the formula wherein X1 and X2 are independently selected from the group consisting of chlorine, bromine, nitro and methyl.

Polymers with relatively high amounts of first units have outstanding tensile strengths and elongations in the undrawn state, which yields exceptionally tough fibers and films, for example. It is preferred if about 97.5 to about 95 mole percent of first unit and about 2.5 to about 5 mole percent of second unit is present.

Undrawn polymers of the instant composition, in fiber form, frequently have tensile strengths of 15 g/denier or more combined with tensile elongation to break of 5% or more, and such fibers are preferred.

Aramids containing lesser amounts of first units are more readily drawable, and upon drawing give parts, for example fibers or films, with an outstanding combination of tensile strength, tensile elongation and tensile modulus. ThuS it is also preferred if the polymer contains about 75 to about 92 mole percent of first units and about 25 to about 8 mole percent of.

second units.

It is preferred if both 30 and X2 are identical.

It is more preferred if X1 and X2 are chlorine or nitro, and especially preferred if 30 and 3(2 are chlorine.

The 2,2'-disubstituted-4,4'-bibenzoic acids (or their acid halides, especially chlorides, which are often used in the polymerization process to make aramids) may be made by methods known to those skilled in the art. Synthesis of the acyl chlorides of 2,2'-dibrorno-and 2,2'-dinitro-4,4'-bibenzoic aci4s are described in U.S. Patent 4,384,107. Synthesis of the corresponding 2,2'-dimethyl compound is described in H. Schmidt and D. Guo, Makromol. Chem., vol. 189, p. 202 9-2037 (1988) 2,2'-Dichloro-4,4'-dicyanobiphenyl may be made by the procedure described in U.S. Patent 3,872,094 and then hydrolyzed in refluxing (atmospheric pressure) 20% aqueous NaOH, and then neutralized with acid to obtain the 2,2 -dichloro-4, 4 -bibenzoic acid.

This invention also concerns an essentially undrawn aramid fiber having the novel properties of a tensile strength of at least 15 grams per denier and a tensile elongation of at least 7%.

The polymers may be made by techniques that are known for making aramids, for example see British Patent 1,547,802 and U. S. Patent 3,673,143. The polymers, as made, should be of sufficient molecular weight so that fiber or films may be formed. Thus the polymers should have an inherent viscosity of about 4 or more (for the procedure for measuring inherent viscosity, see below).

Such polymers may be spun into fibers or made into other shapes by methods known for prior art aramids, see for example U.S. Patent 3,673,143, Example 2 for forming a film, and U.S. Patent 3,767,756 for spinning a fiber.

One preferred form of this composition is as an essentially undrawn fiber, whch has a Lensile strength of at least about 15 grams per denier and an elongation to break of at least about 5 percent.

Many of the instant polymers are drawable, and upon drawing exhibit substantially improved properties compared with undrawn polymer, particularly tensile modulus. In order for aranid polymers to be drawable, and upon drawing to exhibit optimal physical properties, 6 -it is believed, but Applicant does not wish to be bound by the hypothesis, that aramid polymers must have the following intrinsic properties: that they be soluble in a solvent for fiber spinning; that they be stable under the drawing conditions (especially high temperature); that they be largely amorphous in the as-spun (undrawn) state; and that they exhibit increased crystallinity and high orientation in the drawn state. Polymers are soluble in sulfuric acid. While many aramids may meet some of these conditions, Applicant believes that only a small fraction of all aramid polymers theoretically possible would meet all these conditions.

The drawable polymers of this invention are useful in fibers and films where high tensile strength and tensile modulus are important, as for ropes and composites.

The preferred temperature for drawing is about 350°C to about 575°C, most preferably about 400°C to about 520°C. The temperature needed for any particular arainid can be readily determined by heating the aramid (say a film or fiber) to a given temperature and trying to draw by band. If no draw is apparent, higher temperatures should be tried.

The force needed to draw the fiber is determined by relatively easy experimentation. The aranid can be drawn to a specific draw value, provided that the aramid does not break at that amount of draw. Alternatively the aramid can be drawn, by a certain td;ce (but less than that required to break the arainid)'. This force can be readily determined for any aramid and temperature by heating the aramid to drawing temperature and applying a just enough force to draw it whSle measuring the force with a tension gauge.

By the phrase "drawn at least X%" is meant the value computed by the following formula: (final length) -(original length) original length It is preferred if the aramid is drawn at least 1%. It is also preferred if the tensile strength of the drawn aramid is at least 1.25 times the tensile strength of the undrawn aramid. -The orientation angle of the drawn aramid is often 12° or less. The orientation angle may be measured (in fibers) by the following method: A bundle of filaments about 0.5 mm in diameter is wrapped on a sample holder with care to keep the filaments essentially parallel. The filaments in the filled sample holder are exposed to an X-ray beam produced by a Philips X-ray generator (Model 120458) operated at 40 kv and 40 ma using a copper long fine-focus diffraction tube (Model PW 2273/20) and a nickel beta-filter.

The diffraction pattern from the sample filaments * 20 is recorded on Kodak DEF Diagnostic Direct Exposure X-ray film, in a Warhus pinhole camera. Collimators in the camera are 0.64 mm in diameter. The exposure is continued for about fifteen to thirty minutes (or generally long enough so that the diffraction feature to be measured is recorded at an optical density of -1.0).

A digitized image of the diffraction pattern is recorded with a video camera. Transmitted intensities are calibrated using black and white references, and gray level (0-255) is converted into optical density.

The diffraction pattern of fibers of this invention has two prominent overlapping equatorial reflections at a scattering angle of approximat44 20° and 22°; the inner (-20°) reflection is used for the measurement of Orientation Angle. A data array equivalent to an azimuthal trace through *the two selected equatorial -peaks (i.e. the inner reflection on each side of the pattern) is created by interpolation from the digital image data file; the array is constructed so that one data point equals one-third.of one degree in arc.

The Orientation Angle is taken to be the arc length in degrees at the half-maximum optical density (angle subtending points of 50 percent of maximum density) of the equatorial peaks, corrected for background. This is computed from the number of data points between the half-height points on each side of the peak (with interpolation being used, that is not an integral number). Both peaks are measured and the Orientation Angle is taken as the average of the two measurements.

The apparent crystallite size of the drawn aramid is usually larger than that of the undrawn aramid.

Larger crystallite sizes are believed to denote increased crystallinity in the aramid, and an improvement in properties, especially tensile modulus.

The apparent crystallite size is measured by the following procedure: Apparent Crystallite Size is derived from X-ray diffraction scans, obtained with an X-ray diffractometer (Philips Electronic Instruments; cat, no. PW1075/00) in reflection mode, using a diffracted-beam znonochromator and a scintillation detector. Intensity data are measured with a rate meter End recorded by a computerized data collection and reduction system.

Diffraction scans are obtained using the instrumental settings: Scanning Speed: 1° 20 per minute Stepping Increment: 0.025° 20 Scan Range; 15° to 30° 20 Pulse Height Analyzer; Differential Diffraction data are processed by a computer program that smooths the data, determines the baseline, and measures peak locations and heights.

S The diffraction pattern of fibers from this invention is characterized by two prominent equatorial X-ray reflections. These peaks, occurring at approximately 200_210 and 22° 28 (scattering angle), overlap substantially and may be difficult to resolve.

Apparent Crystallite Size is calculated from the measurement of the half-height peak width of the first (lower scattering angle) equatorial diffraction peak.

Because the two equatorial peaks overlap, the measurement of the half-height peak width is based on the half-width at half-height. For the 200_2l0 peak, the positionS of the half-maximum peak height is calculated and the 20 value corresponding to this intensity is measured on the low angle side. The difference between this 26 value and the 26 value at maximum peak height is multiplied by two to give the half-height peak (or "line") width.

In this measurement, correction is made only for instrumental broadening; all other broadening effects are assumed to be a result of crystallite size. If B is the measured line width of the sample, the corrected line width S is fla (B2-b2)1/2 where b' is the instrumental broadening constant. b' is determined by measuring the line width of the peak located at approximately 28.5° 26 in the diffraction pattern of a silicon crystal powder sample.

The Apparent Crystallite Size is given by ACS (KX)/(A cos B), wherein K is taken as one (unity) is the X-ray wavelength (here 1.5418 A) S is the corrected line breadth in radians 0 is half the Bragg angle (halt of the 20 value of the selected peak, as obtained from the diffraction pattern).

It is preferred if the aramid to be drawn is in the form of a film or fiber, and especially preferred if the aramid is in the form of a fiber.

It is preferred if the aramid that is drawn consists essentially of about 70 to 99 mole percent of a first unit of the formula H Hil II

-N N-C C-

and about 30 to 1 mole percent of.a second unit of the formula

H

wherein X and X2 are independently selected from the group consisting of chlorine, bromine, iiitro and methyl.

Preferred compositions of aramids of this formula are as enumerated above.

The drawing of arainids in the present invention occurs in the substantial absence of water or other solvents. By substantial absence of water or other solvent is meant less than about 5% water or other 11' solvent, preferably less than about 2%. The molecular weight of the aramids should be high enough to be able to form a tibet.

Thus, the polymers should have an inherent viscosity of about 4 or more in sulfuric acid. A procedure for measuring inherent viscosity is given in U.S. Patent 3,673,143, column 17, lines 10 et. seq., which is hereby included by reference.

The apparatus useful for drawing the aramids may be quite varied. It may even be done by hand, but for production more automated continuous processes are desirable. Apparatus useful for such processes are disclosed in U.S. Patents 3,869,430 and 4,500,278, which are hereby included by reference.

In the following examples, fiber properties are measured by methods described in U.S. Patent 3,869,429, column 10 line 28 to column 11, line 10, which is hereby included by reference.

EXAMPLES

In the following examples, all chemicals were reagent grade and purchased from common vendors unless otherwise stated. Terephthaloyl chloride was distilled (90°C, 0.1 mm Bg), p-phenylenediamine was sublimed (80°C, 0.3 mm Hg), and calcium chloride was dried (400°C) under nitrogen prior to use. All reactions were conducted under an atmosphere of dry nitrogen or argon.

Melting points (all temperatures are reported in centigrade) were measured on a Thomas iiover Uni-Melt apparatus or a TA-9900 Computer-Thermal Analyzer DSC instrument. All melting points are uncorrected.

Infrared spectroscopy was performed on a Nicolet 60SX spectrophotometer. Thermogravimetric analysis was performed on a 2950 TGA TA instrument. Differential scanning calorimetry was performed on a 2910 DSC TA instrument.

EXA1LE 1 ___ 2.2' -Dichloro-4. 4 -hiphenyldicarbonyl-P?D-T copolymer Into a flame-dried glass resin kettle under argon purge fitted with an air-driven cage-type stirrer was $ added 110 rnL of anhydrous N-methylpyrrolidone and 8.62 g (77.7 mmol) of dried calcium chloride. The suspension was stirred for 15 mm, followed.by the addition of 3.00 g (27.7 mmol) of sublimed para-phenylenediamine.

The mixture was stirred for 5 mm with periodic gentle heating (heat gun) to aid in dissolution of the para-phenylenediamine. The reaction mixture was cooled in an ice bath, and a mixture of 4.67 g (23.0 mmol) of terephthaloyl chloride and 1.64 g (4.71 mmol) of 2,2'-dichloro-4, 4 -biphenyldicarbonyl chloride were added.

cooling was continued for 2 mm, after which time the ice bath was removed. The reaction mixture gelled after 9 mm, and crumbed after 11 mm. Stirring was continued for a total reaction time of 2 hours. The polymer was washed in a blender 4 times with distilled water and filtered. The copolymer was dried in a vacuum oven (80°C, 20 in Eg) for 3 days to afford 7.13 g product as a pale yellow crumb: IjrJi=4.SG (H2S04); Thermogravimetric analysis (TGA) indicates incipient weight loss at 4 97°C * in nitrogen, and at 472°C in air; Differential scanning calorimetry. (DSC) indicates an exotherm beginning at 318°C in nitrogen; lB (XBr) 3430, 1650, 1515, 1310, 1090.

EX}WLE 2 2.2 -DichlSro-4.4 -biphenvldicarbonvl-PPD.-T eotolvmer Into a flame-dried glass resin kettle under argon purge fitted with an air-driven cage-type stirrer was added 315 mL of anhydrous N-methylpyrrolidone and 24.71 g (0.2226 mol) of dried calcmuiii chloride. The suspension was stirred for 20 nUn, followed by the addition of 8.60 g (79.5 mmol) of sublimed pan-phenylenediamine. The mixture was stirred for 7 ntin with periodic gentle heating (heat gun) to aid in dissolution of the para-phenylenediamine. The reaction mixture was cooled in an ice bath, and a mixture of 12.109 g (59.64 mmol) of terephthaloyl chloride and 6.920 g (19.89 mmol) of 2,2'-dichloro-4,4'-biphenyl-dicarbonyl chloride were added. Cooling was continued for 2 mm, after which time the ice bath was removed.

The reaction mixture gelled after 2.5 mm, and crurnbed after 5.0 mm. Stirring was continued for a total reaction time of 2 hours. The polymer was washed in a blender with two portions of distilled water, once with 23 alcohol (ethanol/benzene), and twice more with distilled water. The 1:3:4 2,2'-dichloro-4,4'- biphenyldicarbonyl. chloride:terephthaloyl chloride:para-phenylenediamine copolymer was dried in a vacuum oven (80°C, 20 in Hg) for 4 days to afford 21.85 g product as a pale yellow crumb: TIii,J1a5.42 (E2S04); Thermogravimetric analysis (TGA) indicates incipient weight loss at 504°C in nitrogen, and at 494°C in air; Differential scanning calorimetry (PSC). indicates an exotherm beginning at 331°C in nitrogen; ZR (KBr) 3430, 2920,1650, 1510, 1100.

ZXA?eLE 3 2.2' -Dichloro-4. 4 -biphenyldicarbonyl-PPD-T copolymer Into a flame-dried glass resin kettle under argon purge fitted with an air-driven cage-type stirrer was added 110 rnL of anhydrous N-xnethylpyrr&lidone and 8.62 g (77.7 mmol) of dried calcium chloride. The suspension was stirred for15 mm, followed by the addition of 3.00 g (27.7 mmol) of sublimed para-phenylenediamine.

The mixture was stirred for 5 mm with periodic gentle beating (heat gun) to aid in dissolution of the pan-phenylenediamine. The reaction mixture was cooled in an ice bath, and a mixture of 5.069 g (24.97 mmol) of terephthaloyl chloride and 0.965 g (2.774 irimol) of 2,2' -dichloro-4, 4 * -biphenyldicarbonyl chloride were added. Cooling was continued for 2 mm, after which time the ice bath was removed. The reaction mixture gelled after 8 mm, and crumbed after 13 mm. Stirring was continued for a total reaction time of 2 hours. The polymer was washed in a blender with five portions of distilled water. The 1:9:10 2,2'-dichloro-4,4'- biphenyldicarbonyl chloride:terephthaloyl chloride:para-phenylenediamine copolymer was dried in a vacuum oven (80°C, 20 in Hg) overnight to afford 5.14g product as a pale yellow crumb: lflnh=S.35 (H2504); Thermogravimetric analysis (TGA) indicates incipient weight loss at 4 63°C in nitrogen,. and at 477°C in air; Differential scanning calorimetry (DSC) indicates an exotherm beginning at 335°C in nitrogen; IR (lear) 3420, 1650, 1510, 1310, 1105.

EXNLE 4 2.2' -Dichloro-4. 4 * -bivhenvldicarbonyl-PPD-T conolymer Into a flame-dried glass resin kettle under argon purge fitted with an air-driven cage-type stirrer was added 360 mL of anhydrous N-methylpyrrolidone and 28.45 g (0.2563 mol) of dried calcium chloride. The suspension was stirred for 15 mm, followed by the addition of 9.88 g (91.36 mmol) of sublimed para-phenylenediamine. The mixture was stirred for 5 mm with periodic gentle heating (heat gun) toaid in dissolution of the para-phenylenediamiñe. The reaction * mixture was cooled in an ice bath, and a mixture of 18.085 g (89.08 mmol) terephthaloyl chloride and 0.795 g (2.284 mmol) of 2,2 -dichloro-4, 4'-biphenyldicarbonyl chloride were added. Cooling was continued for 2 mm, after which time the ice bath was removed. The reaction mixture gelled after 2 mm, and crumbed after 7 nUn.

Stirring was continued for a total reaction time of 2 hours. The polymer was washed in a blender with two portions of distilled water, once with 23 alcohol (ethanol/benzene), and twice more with distilled water.

The 2.5:97.5:100 2,2'-dichloro-4, 4'-biphenyldicarbonyl chloride:terephthaloyl chloride:para-phenylenediamine copolymer was dried in a vacuum oven (80°C, 20 in Hg) overnight to afford 22.86 g product as a pale yellow crumb: T1j.Jr4.38 (112504).

General Proeedure for Making Soin * Dote and Spinnina On the day before the spin, the polymer to be used was poured into a flat pan and heated under vacuum to about 80-100°C, overnight in the vacuum oven. A double helix mixer made by Atlantic Electric was assembled and placed under an inert purge for 6 to 24 hr. A basin that fits over the bowl of the mixer was put in place and filled with dry ice. A cylinder containing 40 ml of fuming sulfuric acid (100.1%) and öovered with parafilm was weighed, and then the acid was poured into the mixer by means of a large funnel. The mixer was started at low speed (one quarter turn of the crank from the lowest * possible speed), and the cylinder and parafilm were reweighed to give an accurate weight of acid. The dry ice was broken up with a spatula, allowing it to settle, then more was added. The weight of the acid and the desired solids content were used to calculate the polymer needed. A bottle and small plütic funnel were placed on the balance and tared, then the polymer was removed from the oven and added until the weight reached the desired amount plus about 0.05 grains. The tunnel was removed, the bottle was removed and capped, and the balance was reset to zero, then the sealed bottle was weighed. By this time, the mixer bad usually reached - 13 to -18°C, and the sulftiric acid had formed "snow". ent

If this had not yet happened, the dry ice was resettled.

The polymer was added only after the acid was snowed".

The mixer was stopped, and the polymer was added to the mixer via a large funnel. The mixer was then resealed and restarted, and the bottle and cap were reweighed to give the weight of polymer added. The solids concentration was calculated from the actual polymer and acid weights.

The dope was allowed to mix for five to ten minutes in the dry ice bath, then it was removed and the mixer was left to come up above 0°C, still stirring at a low rate of speed (about 18 to 20 rpm). Once the mixer warmed to just above 0°C, the heater hoses were connected and the heater was started, set at the temperature which yielded a mixer temperature of 70°C.

Heating to 70°C took about half an hour. At the end of this time, the dope clinging to the sides and blades of the mixer was scraped down into the bottom of the mixer until it was all being mixed. The scraping was repeated as necessary during this stage of mixing. The mixer speed was increased to 55 rpm, and the dope was mixed at this speed and temperature for an hour and a half. At the end of this time, the heater set-point was turned up to the temperature which would yield aznixer temperature of 80°C. It took about ten to fifteen minutes for the mixer to warm to 80°C; dnce at temperature, mixing continued fora half hour to an hour.

During mixing, the electronic equjpment (including the components) was started and set up ready to spin.

Also, small beakers (800 ml) were each filled with 1-2 g of sodium bicarbonate and distilled water to the brim.

After mixing was completed, the mixer speed was lowered to a half-turn from bottoming out at the lowest speed.

The mixer was then turned of 1, and the alien bolts on the base plate were loosened. The spinning tell was 1 ant positioned beneath the mixer so that the opening containing the piston was directly beneath the mixer opening. Then the mixer base plate was slid open and the mixer was restarted, allowing the dope to flow down S into the cell. Once the cell was full, the mixer was resealed and the base plates of the cell were attached.

The cell was then turned right side up, and the piston depressed. Then the space above the piston was filled with water and the top plate was attached. The cell was set in place in the spinning unit and the necessary hookups were made; the pressure sensor was calibrated.

The air line was then turned on, and a small amount of dope was pumped out of the cell before *the spinneret plate was attached. The coagulant bath was slid under the cell, and the air gap and guides were adjusted. The water spray was turned on and the traverse was started, then the spin was begun. The fiber was strung up to a waste bobbin as conditions were adjusted, then moved to a collection bobbin when they were set. The first and last fiber collected on the waste bobbin (cleaned periodically throughout the spin) was set aside for inherent viscosity testing. It was placed in bottles and treated as the bobbins below.

Once bobbins had been filled, they were removed to beakers containing the sodium bicarbonate solution.

They remained in those beakers overnight, then were washed for 40 minutes in running distilled water. After that, they were set to air dry in the hood..

EXMeLE S The spin dope was prepared as follows: a double helix mixer (made by Atlantic) was prechilled with a dry ice bath, then 72.08 g of 100.05% fuming sulfuric acid was poured in and the mixer turned on slowly while maintaining a nitrogen purge. The acid was chilled to -5°C with the external dry ice bath. At this point the sulfuric acid had formed a "snow" and 17.426 g of --polymer was added to the mixer. The polymer was made as in Example 1. This polymer had an average inherent viscosity of 4.97 dl!;. The polymer was mixed with the sulfuric acid snow for twenty minutes to provide good solid-solid mixing. During this time 0.645 g of additional sulfuric acid was added to bring the polymer concentration to 19.33%. The dry ice was removed and the mixer dipped in warm water to bring its temperature above freezing before connecting and turning on the heating unit, since this unit uses water as the circulating fluid. The heater was turned on and set at 75°C and the stirring speed set at 20 rpm. In a half hour, the mixer temperature had reached 70°C, the stirring speed was increased from 20 to 55 rpm and the spin dope adhering to the sides of the mixer was scraped into the bowl. During scraping, the mixer temperature increased to 72°C and the heater setpoint was turned down to 72°C to maintain the mixer temperature at 70°C.

The dope mixed under these conditions for 90 minutes and then the bath setpoint was increased to 82°C. After reaching 79°C, the dope was mixed for an additional 45 minutes. The mixer speed was reduced to 20 rpm and a preheated spinning cell was filled via the mixer base plate.

All fiber was spun into a stagnant water bath at 0-5°C with a 1 cm air gap. The bobbins were placed in a sodium bicarbonate solution overnight, washed in distilled water and air dried the following day.

Spinning conditions are givenbelow. Fibers 1-8 were spun with a spinneret with diameter and length of 0.004" x 0.012". Fibers 9-14 were spun with a 0.003" x 0.009" spinneret.

Jet Temp Tenacity Elongation M0du1u3 Thax Fiber (rrpm) 5SF 1°C) (god) (god) god 1 31.7 3.56 74.7 15.7 7.37 362 17.3 2 33.0 4.50 75.4 15.9 6.99 405 18.5 3 23.6 4.96 76.4 17.0 7.33 408 17.8 4 19.7 8.32 76.8 15.7 7.05 382 16.5 $ 11.2 9.65 76.9 17.3 7.12 412 18.4 6 11.8 7.11 77.0 16.5 7.4 426 18.5 7 12.1 11.11 77.0 13.0 5.19 437 17.0 8 12.0 14.04 77.0 11.0 4.84 385 16.5 9 43.0 5.35 74.8 16.6 6.58 436 17.8 45.6 2.81. 75.2 15.0 7.21 362 16.6 11 43.8 7.61 76.0 12.9 5.6 393 14.2 12 43.3 1.52 75.9-14.4 8.51 317 15.2 13 42.5 4.16 76.6 15.6 7.52 382 16.5 14 44.7 8.91 76.B 12.9 5.62 395 14.7 All tensile measurements were made on 1" samples.

The inherent viscosity of fiber collected before sample 3. was 4.49. The inherent viscosity of fiber collected after sample 14 was 4.45 dug.

Fiber sample 3 was drawn' continuously at 450°C with a 2.1% draw to give drawn fiber with T/E/N/Thax of 22.6/4.0/606/24.3.

Fiber sample 5 was drawn. continuously at 400°C with a draw of 1.4% to give drawn fiber with T/t/24/Tmax of 20.0/3.9/590/21.2.

* Optical microscopy of sample 14 showed a disruption of the pleat structure typical of PPD-T.

Fiber 2 was back wound, then drawn on hot pins. An approximately six inch length of the fiber was taped with glass tape to two metal spatulas, then measured on a ruler marked in hundredths of an inch. It was passed over the hot pin several times and then remeasured.

Draw was calculated as a percentage. The first drawing attempt was at 550°C, making four passes with the fiber.

Three of these four samples broke; one was retained as sample 1. The hot pin temperature was reduced to 500°C, three samples were made, none broke. Another trial was done at 550°C with only two passes per fiber over the hot pin. This produced the best draw and none of the samples broke. The results of sample testing are shown below.

Tenacity Elongation Modulus Sample Temp Ct) % Draw qpd % qpd 550 2.2 25.0 4.0 650 16 500 1.8 21.4 4.5 536 17 500 2.0 22.0 4.4 590 * 18 500 2.2 18.7 3.8 591 19 550 2.5-2.6 22.9 3.9 635 550 3.4 20.1 3.8 618 2]. 550 2.8 22.3 4.0 646 EXMLE 6 The polymer of Example 4 had an inherent viscosity of 4.38 dl/g. The polymer was mixed with fuming sulfuric acid into a 19.4% solids dope as above. Set-up started with a 1.3 cm air gap into chilled water, using a 3 nil spinneret (Samples 1-6). In the middle of the spin, the spinneret was changed for a 2 mu spinneret (samples 7-13) and then at the end of the spin a 3 nil spinneret (samples 14-16) was used to finish the spin.

-

Jet Temp Tenacity Elongation Modulus ThLax Fiber (mprn) 5SF (C) tgpd) % tcpd) 3. 30.7 2.4 70.6 17.8 6.8 329 20.9 2 32.1 3.4 70.9 19.6 6.7 357 24.5 3 31.8 3.0 10.1 20.5 7,4 321 22.9 4 31.3 2.1 70.3. 18.1 7.3 290 22.0 3.7.1 3.8 10.6 18.4 7.3 293. 21.0 6 19.9 2.5 71.0 18.9 1.3 309 21.8 7 14.4 3.4 72.7 17.2 6.0 362 19.3 8 14.5 7.9 73.8 17.5 4.7 488 19.6 9 14.6 5.5 74.1 20.0 5.5 462 25.0 14.3 2.6 75.1 14.7 5.6 344 17.2 12. 30.7 3.8 75.5 16.9 5.6 388 18.3 12 30.8 5.0 75.7 16.8 5.9 360 19.0 13 29.9 2.5 76.0 15.8 6.5 294 17.6 14 34.1 5.1 74.5 15.9 5.6 360 18.3 34.3 2.9 75.1 18.0 8.0 259 19.4 16 35.6 6.5 76.1 14.4 5.9 303 16.6 The density of samples 8 and 9 were measured to be 1.4378 g/cc.

Optical microscopy onsample 5 showed the pleated structure found in conventional PPD-T samples.

Fiber 11 was hand-drawn 2% at 450°C. (An approximately six inch length of fiber was taped with glass tape to two metal spatulas, then measured with a ruler marked in hundredths of an inch, drawn at the specified temperature and then remeasured.) The drawn fiber had T/E/M/Trnax of 18.5/4.2/419/21.2 All tensile measurements were made on 2.54 cm samples.

EXAMPLE 7

A 19.3% solids spin dope was prepared from several polymer samples made by the procedure 0! Example 3. A 3 mil spinneret was used throughout the spin. ?nt

C

F

Temp tenacity Elongation Modulus Tinax Satr1e (nin) 5SF (C) (qpd) (qpd) qpd 1 62.7 2.9 13.2 16.0 6.4 420 1.6.8 2 50.0 3.3 75.3 16.0 6.4 428 17.9 3 54.2 3.7 75.5 16.0 6.3 429 17.0 4 52.9 2.5 75.4 14.1 6.5 362 15.6 33.8 4.9 76.6 15.7 6.6 402 19.0 6 33.8 8.3 76.9 11.2 6.4 416 19.3 7 32.0 3.1 77.1 17.0 7.4 405 18.3 8 31.9 3.8 77.8 17.2 6.8 425 11.8 9 34.1 6.1 77.8 17.2 6.8 416 18.9 21.0 4.3 77.8 15.7 6.5 416 18.0 13. 21.3 9.4 77.8 17.1 6.0 436 20.2 12 21.1 12.8 77.6 12.6 5.0 364 14.1 13 20.6 11.2 76.8 17.5 6.]. 442 19.6 14 20.4 6.3 76.9 17.1 6.4 437 19,0 34.3 6.0 76.5 17.6 6.2 444 18.8 The inherent viscosity of fiber collected before sample 1 was 4.21 dug; fiber collected after sample 15 had an inherent viscosity of 4.32 dug.

A series of hot pin drawings were done on fiber 15.

The fiber was taped, measured, drawn and remeasured as described above. Fibers which drew within 0.5% of each other at the same temperature were grouped together as a single sample for tensile testing.

Temp 1 Tenacity Elongation Modulus Tmax Sample (°C) Draw qpd qpd qpd 16 300 1.7 20.9 4.0 568 22.6 17 350 2.0 20.3 4.2. .468 20.8 18 350 1.3 18.7 3.8 485 18.7 19 400 2.2 16.6 3.3 507 21.5 450 1.6 19.6 3.8 536 22.8 21 450 2.2 20.4 35 64$ 20.4 22 500 1.5 23.8 4.1 581 23.8 23 500 2.1 23.2 4.2 541 23.9 24 550 2.7 21.5 3.5 570 22.4 600 2.8 18.4 2.3 639 23.0 26 600 2.4 22.0 3.4 645 24.8

EXAMPLE B

A 19.3% solids spin dope of polymer from Example 2 was prepared. A 3 mu spinneret was used for sample 1, a 4 mil for samples 2-7and a threemil for 8-15.

Jet Temp Tenacity Elongation Modulus Thax Sample (mpm) 55? (°C) (qpd} % (qpd) pd 3. 40.0 2.5 73.0 17.0 8.3 368 18.6 2 42.2 2.B 15.3 13.5 8.3 293 14.7 3 31.0 2.2 76.3 13.4 8.5 305 15.3 4 30.7 4.0 77.5 13.9 7.1 320 14.0 24.3 2.9 17.9 15.4 8.4 340 18.2 6 20.9 6.4 78.1 14.7 7.5 355 16.7 1 17.9 3.9 78.2 16.4 8.3 362 18..4 8 41.8 2.4. 77.0 15.1 8.1. 358 16.9 9 41.6 4.0. 17.3 15.3 6.8 385 17.2 40.5 5.7 77.3 13.6 6.6 373 15.8 11 28.3 2.7 76.5 14.8 8.0 342 17.3 12 27.3 5.0 76.6. 15.6 1.0 400 11.9 13 9.6 3.2 77.2 16.2 8.3 356 17.2 14 8.8 6.1 77.4 13.4 6.7 345 16.4 4.8 3.6 77.9 15.0 8.1 311 18.6 Fiber collected before sample 3. had an inherent viscosity of 4.94 dl/g and fiber collected after sample had an inherent viscosity of 4.50 dug.

sample 1 was hand drawn as described in Example 7 and had the following properties: Terp Tenacity Elongation Modulus Tmax Sample (C) Draw qpd qpd qpd 16 475 2.1 22.4 4.1 528 22.4 17 475 3.6 24.9 4.4 553 24.9 18 475 3.1 23.5 4.4 533 24.4 19 500 3.7 22.3 4.0 535 21.4 500 3.1 21.8 3.9 517 21.8 21 525 2.8 23.9 4.2 600 25.6 22 525 3.7 23.5 4.4 516 24.2 23 550 3.5 23.9 4.2 520 25.1 24 575 3.7 24.4 4.4 486 25.5 575 3.1 21.0 4.0 420 21.0 26 600 3.6 19.3 3.7 495 22.8 27 450 3.2 21.7 4.5 439 24.0 28 400 2.7 21.7 4.6 454 23.3 29 350 3.1 22.8 4.4 520 23.2 350 3.9 23.0 4.7 434 23.2 31 -300 3.6 18.1 3.9 459 18.1 32 300 4.1 22.8 4.8 448 23.0 33 250 4.3 23.6 4.8 450 24.1 34 250 3.4 21.7 5.0 371 21.7 250 1.6 21.7 4.9 405 21.7 36 250 3.2 22.3 4.6 465 22.3 37 250 1.1 21.7 4.5 486 21.7 38 250 1.8 23.3 4.4 543 23.5 sample B was drawn continuously through a nitrogen purged oven. The draw roll was maintained at 1.99 25.

meters per minute. The teed roll was varied from 1.88 --to 1.91 mpnt to give a draw of 4.4-5.9%. The results are shown below: Teup % Tenacity Elongation Modulus Tmax Sample 1°C) Draw qpd % qpd qpd 39 400 4.7 23.1 4.6 534 25.4 400 5.6 23.5 4.2 567 26.5 41 450 4.4 24.8 4.5 625 26.1 42 500 4.4 23.1 4.6 529 26.3 43 500 5.5 22.8 4.4 560 24.7 44 525 4.6 21.6 4.1 585 25.0 525 5.9 24.1 4.4 505 27.8 X-ray analysis showed the following: Samnle ACS. A B 10° 27 41 8.7° 24 8.6° .25 EXA?WLE 9 2.2 -Diehloro-4. 4 -biphenyldicarbonvi-PPD-T ecqolymer Into a flame-dried glass resin kettle under nitrogen purge fitted with an air-driven stirrer was added 145 niL of anhydrous N-methylpyrrolidone and 14.24 g (0.1283 mol) of dried calcium thloride. The suspension was heated until dissolution of the calcium chloride was complete. The solution was cooled to room temperature and 9.910 g (91.64 minol) of sublimed para-phenylenediamine was added and stirred at room temperature until completely dissolved. The reaction mixture was cooled in an ice bath. A mixture of 18.419 g (90.73 mmcl) of terephthaloyl chloride and 0.319 g (0.917 mmol) of 2,2'-dichloro-4,4'-biphenyl-dicarbonyl chloride, was added in two portions, 45 seconds apart. Cooling was continued for 70 seconds, after which time the ice bath was removed. The reaction mixture gelled after 2 mm, and crumbed after 3.75 mm.

Stirring was continued for a total reaction time of 2 hours. The polymer was washed In a blender with two portions of distilled water, once with 28 alcohol (ethanol/benzene), and twice more with distilled water.

The 1:99:100 2, 2'-dichloro--4, 4 -biphenyldicarbonyl chloride: terephthaloyl chloride:para-phenylenediaxnine copolymer was dried in a vacuum oven (80°C, 20 in Hg) overnight to afford 22.3 g product as a pale yellow crumb: linh 4.33 (112504).

EXXPLE 10 2.2 -dinitro-4,4!-biphenvldiearbonvl-PPD-T copolymer Into an oven-dried resin kettle equipped with an air-driven basket stirrer, a drying tube, and a nitrogen inlet was added, in the glovebox, 11.660 g (0.1078 rnol) of para-phenylenediamine and 240 g of a calcium chloride/NM? premix containing 20.7 g (0.187 inol) of calcium chloride. The mixture was removed from the glovebox and stirred under a rapid nitrogen flow for * 2 h, then cooled in an ice bath approximately 5 mm. To the cooled mixture was added 7.680 g (37.83 amol) of terephthaloyl chloride. Stirring was continued 5 mm, the ice bath was removed, and a mixture of 13.716 g (67.56 mrnol) of terephthaloyl chlorideand 0.997 g (2.70 mmol) of 2,2 -dinitro-4, 4 -biphenyldicarbonyl chloride was added. The acid chloride was used in a 0.27% molar excess. After stirring at medium speed for one minute, the reaction mixture was stirred at full speed. The reaction mixture opalesced after 73 a, gelled after 153 T, and crumbed after 220 s. stirring was continued for 15 in following crumb formation. The 2.5:97.5:100 2,2 -dinitro-4,4 -biphenyldicarbonyl chloride:terephthaloyl chloride:para-phenylenediamine copolymer crumb was washed and filtered three times with distilled water, once with -1.5% NaOH (ag), and twice more with distilled water, then dried in the oven (1400C, air) overnight to afford 25.97 g of the product as a yellow crumb: fljrJt 6.2.0 dL/g (112504).

EXAMPLE 11

2.2 -dinitro-4. 4 -hiphenvldicarbonyl-PPD-T coDolymer Into a flame-dried resin kettle equipped with an air-driven basket stirrer, a drying tube, and a nitrogen inlet was added, in the glovebox, 11.660 g (0.1078 znol) of para-phehylenediamine and. 240 g of a calcium chloride/N}'a' premix containing20.7 g (0.187 mol) of calcium chloride. The mixture was removed from the glovebox and stirred under a rapid nitrogen flow for 1.5 h, then cooled in an ice bath approximately 5 rain.

To the cooled mixture was added 7.680 g (37.83 mrnol) of terephthaloyl chloride. Stirring was continued 5 rain, the ice bath was removed, and a mixture of 13.170 g (64.87 mxnol) of terephthaloyl chloride and 1.995 g (5.40 rnmol} of 2,2 -dinitro-4,4 -biphenyldicarbonyl chloride was added. The acid chloride was used in a 0.28% molar excess. After stirring at medium speed for one minute, the reaction mixture was stirred at full speed. The reaction mixture opalesced after 80 s, gelled after 160 a, and crumbed after 240 a. Stirring was continued for 15 in following crumb:formation. The 5:95:100 2,2 -dinitro-4,4 -biphenyldicarbonyl chloride:terephthaloyl chloride:para-phenylenediaxnine copolymer crumb was washed and filtered three times with distilled water, once with -1.5% NaOH (ag), and twice more with distilled water, then dried in the oven (100-110°C, 20-25 mm Hg, N2) overnight to afford 25.64 g product as a yellow crumb: jjth= 6.05 dL/g (112804); Thermogravimetric analysis (TGA) indicates incipient weight loss at 4 14°C and rapid weight loss at 5 66°C in nitrogen, and incipient weight loss at 394°C and rapid weight loss at 555°C in air; Differential scanning S calorimetry (DSC) indicates an exotbernt beginning at 296°C (358°C max., 121 JIg) in nitrogen, a broad melting point at 459°C (second heat), and Tg at 219°C.

EXA14PL 12 2.2 -din itro-4.4 -biphenyldicarborivl-PPD-T eooclvmer Into an oven-dried resin kettle equipped with an air-driven basket stirrer, a drying tube, and a nitrogen inlet was added, in the glovebox, 11.660 g (0.1078 mol) of para-phenylenediamine and 240 g of a calcium chloride/NM? premix containing 20.7 g (0.187 mol) of calcium chloride. The mixture was removed from the glovebox and stirred under a rapid nitrogen flow for 2 h, then cooled in an ice bath approximately 5 mm. To the cooled mixture was added 7.680 g (37:83 wmol) of terephthaloyl chloride, Stirring was continued 5 mm, the ice bath was removed, and a mixture of 12.072 g (59.5 mmol) of terephthaloyl chloride and 3.990g (10.8 mmcl) of 2,2'-dinitro-4,4'-biphenyldicarbonyl chloride was added. The acid chloride was used in a 0.28% molar excess. After stirring at medium speed for one minute, the reaction mixture was stirred at full speed. The reaction mixture opalesced after 85 s, gelled after 131 s, and crunted after 248 s. Stirring was continued for 15 a following crumbformation. The 1:9:10 2,2 -dinitro-4, 4 -biphenyldicarbonyl chloride:terephthaloyl chloride:para-phenylenediamine copolymer crumb was washed and filtered three times with distilled water, once with -1.5% NaOH (aq), and twice more with distilled water, then dried in the oven (140°C, air) overnight to affoid 27.84 g of the product as a yellow crumb: flinh 4.58 dL/g (22504).

-H

* 29 --Although preferred embodiments of the invention have been described hereinabove, it is to be understood that there is no intention to limit the invention to the precise constructions herein disclosed, and it is to be further understood that the right is reserved to all changes coming within the scope of the invention as defined by the appended claims. * * -,

Claims (21)

1. CR-8982CLAIMS1. A drawable aramid random copólymer, consisting essentially of about 70 to 99 mole percent of a first unit of the formula 0. 0 H Hit II -N / N-C C-and about 30 to 1 mole percent of a second unit of the formula wherein X1 and X2 are independently selected from the nitro group consisting of chlorine, bromine,bnd methyl.
2. 2. Anaramidas recited in Claim 1 which contains about 75 to about 92 mole percent of said first units and about 25 to about 8 mole percent of said second units.
3. 3. An aram.td as recited in Claith 1 wherein said X1 and said X2 are identical.
4. 4. An aramid as recited in claim 3 wherein said xt and said X2 are chlorine.S
5. 5. An aramid as recited in Claim 2 wherein said X1 and said X2 are identical.
6. 6. An aramid as recited in Claim 2 wherein said X1 and said DC2 are chlorine.ofClaimsl to6
7. 7. An aramid as recited in any one.(that is drawn.
8. 8. An ararnid as recited in Claim 2 that is drawn.
9. 9. An aramid as recited in Claim 6 which is drawn.
10. 10. An arantid as recited in Claim 2. which contains -about 97.5 to about 95 mole percent of said first units and about 2.5 to about 5 mole percent of said second units.
11. 11. An aramid as recited in Claim 3 wherein said X1 and said DC2 are chlorine or nitro.
12. 12. An aramid as recited in Claim 2 wherein said X1 and said DC2 are chlorine or nitro.
13. 13. An aramid as recited in Claim 10 wherein said DC1 and DC2 are identical.
14. 14. Anaraxnid as recited in Claith 13 wherein said DC1 and said DC2 are chlorine or nitro.
15. 15. An aramid as recited in Claim 14 wherein said DC1 and said X2 are chlorine.ofclaimsl to6or 10 to 15
16. 16. An arajuid as recited in any one Airt the form of an essentially undrawn fiber, said fiber having a -32 -tensile strength of at least about 15 g per denier and a tensile elongation to break of at least about 5%.
17. 17. An aramid as recited in Claim 10 in the form of an essentially undrawn fiber, said fiber having a tensile strength of at least about 15 g per denier and a tensile elongation to break of at least about 5%.of Claims 1 to 15
18. 18. An ararnid as recited in any one tin the form of a fiber or film.
19. 19. An aramid fiber, said fiber having a tensile strength of at least about 15 g per denier and a tensile elongation to break of at least about 7%. - * 20. An arainid copolymer substantially as hereinbefore described in any one of the Examples.-21. An aramid fiber substantially as hereinbefore described in any one of the Examples.Amendments to the claims have been filed as followsCCLAIMS1. A drawable aramid random copolymer, consisting essentially of 70 to 99 mole percent of a 2irst unit of the formula 0 0 H -HI! II -N\/N-C \/C and 30 to 1 mole percent of a second unit of the formula ---ç-wherein X1 and X2 are independently selected from the group consisting of chlorine; bromine,äOmethyl.2. An aramid as recited in Claim 1 which contains 75 to 92 mole percent of said first units and 25 to 8 mole percent of said second units.3. An araraid as recited in Claith 1 wherein said X1 and said X2 are identical.4. An aramid as recited in Claim 3 wherein said X1 and said X2 are chlorine.5. An aramid as recited in Claim 2 wherein said 17. X1 and said X2 are identical..6. An aramid as recited in Claim 2 wherein said X1 and said X2 are chlorine.ofclairnslto6 7. An aramid as recited in any one,4that is drawn.8. An ararnid as recited in Claim 2 that is drawn.9. An aramid as recited in Claim which is drawn.10. An.aramid as recited in Claim 1 which contains 97.5 to 95 mole percent of said first units and 2.5 to 5 mole percent of said second units.11. An aramid as recited in Claim 3 wherein said X1 and said X2 are chlorine or nitro.12. An aramid as recited in Claim 2 wherein said X1 and said X2 are chlorine or nitro.13. An aramid as recited in Claim 10 wherein said X1 and X are identical.14. An aramid as recited in Clai 13 wherein said X and said X2 are chlorine or nitro.15. An aramid as recited in Claim 14 wherein said X1 and said X2 are chlorine.of Claims 1 to 6 or Q to 15 16. An aramid as recited irv any one Ain the form of an essentially undrawn fiber, said fiber having a tensile strength of at least 15 g per denier and a tensile elongation to break of at least 5%.* 17. An aramid as recited in Claim 10 in the form of an essentially undrawn fiber, said fiber having a tensile strength o at least 15 g per denier and a tensile elongation to break of at least 5%.of Claims 1 to 15 18. Art aramid as recited in any one /in the form of a fiber or film.19. An undrawn aramid fiber according to Claim 16 or Claim 17 having a tensile elongation to break of at least 7%.-* c*.
20. 20. An aramid copolymer substantially as hereinbefore described in any one of the Examples.
21. 21. An aramid fiber substantially as hereinbefore described in any one of the Examples.