MXPA06006515A - Methods and compositions for treatment of interferon-resistant tumors - Google Patents

Abstract

The present invention provides a method for the treatment of interferon resistant tumors through the use of recombinant vectors encoding interferon species. In particular it is noted that interferon species provided by recombinant vectors possesses properties not associated with the recombinantly produced interferon proteins. The present invention further provides compositions useful in the treatment of interferon resistant tumors using recombinant vectors encoding interferons.

Description

FIBRIDA FILM PARA-ARAMIDA DESCRIPTIVE MEMORY The present invention pertains to a fibrous para-aramid film, to compositions containing the same, and to a method for making the fibril film and to a paper containing said fibril film. Aramid fibrids are known in the art. Thus, in US 3,756,908, the preparation of aramid polymer fibrids with meta bonds was described. These fibrids can be designed as meta-aramid fibrids and can be used in the papermaking process, preferably when combined with meta or para-aramid pulp and meta-or para-aramid floc. Fibrids are small non-granular non-rigid particles or film-like particles, where in the films one of their dimensions is in the order of the microns and two-dimensional fibers are in the scale of microns. The term "fibrids" is well known in the art and is clear to those skilled in the art. The skilled reader should look in US 2,999,788 where a precise definition is provided and in which the term "fibrids" is further defined in which a fibril particle must possess a capacity to form a paper without sizing. It must also have the ability to bind a substantial weight of discontinuous fiber. The term "fibril film" as used in this invention consistently satisfies the above definition for film-like particles, wherein the Canadian drainage capacity is between 40 and 790. The term "para" is related to the bonds of aramid of the polymer of which the fibrid is constituted. In addition to US 3,756,908, many other references describing meta-aramid fibrids are available. However, there are no known references describing para-aramid fibrids that satisfy the definition given above. Unfortunately, the term "para-aramid fibrid" is sometimes misused to describe the pulp, which is fibrillated and does not have a film-like structure or meet all the requirements given here. Thus, for example, US 6,309,510 describes Kevlar® fibril. Kevlar® is a registered trademark of DuPont for para-aramid. However, this material is highly fibrillated and therefore a pulp by definition. Another example of misuse of the term "fibrid" is found in WO 91/00272 where the fibrides PPTA of Kevlar® are mentioned in example 8. It is evident from the context of this example and its heading that fibers are used, not Fibrids Note also that under the trademark Kevlar® there are no commercially available fibers. The United States patent no. 4,921, 900 is the only reference where it is not immediately clear if the para-aramid fibers mentioned are fibrid. However, by repeating the examples of this reference it was evident that the polymerization step does not lead to a clear solution and that the coagulation of this solution results in polymer particles. Those particles did not meet the above definition of a fibril. Furthermore, the particles obtained contained a high content (60%) of fine particles. Although fibrous para-aramid films according to the definition given above have never been described, it was believed that such fibrids could have beneficial properties when used as a replacement for common meta-aramid fibrids. In particular, better paper properties were seen in relation to strength, porosity, resistance to high temperatures and moisture contents. It was therefore an object of the present invention to obtain methods for preparing para-aramid fibril films and also for said prepared fibril films and products made therefrom. For this purpose the invention relates to a fibrous para-aramid film, wherein at least 95% of the polymer bonds are para-oriented. One dimension of the fibril film is in the scale in microns, while the length and width are much larger, preferably with an average length of 0.2-2 mm and a width of 10-500 μm. It is further preferred that the fibrid films comprise less than 40%, preferably less than 30% fine particles, where the fine particles are defined as particles having a length weighted length (LL) of less than 250 μm.

Para-oriented aramid (aromatic amide) is a condensation polymer of an aromatic diamine for oriented and hitherto known to be a para-oriented aromatic dicarboxylic acid halide (hereinafter abbreviated as "para-aramid") useful in various fields such as fibers, pulp and the like due to its high strength, high modulus of elasticity and high resistance to heat. As used in the present invention, the term "para-aramid" means a substance that is obtained by a polycondensation of a para-oriented aromatic diamine and a para-oriented aromatic dicarboxylic acid halide of which the recurring units have linkages of amide of at least 95% of which are located in the para-oriented or quasi-oriented positions of the aromatic ring, namely in such coaxially arranged or parallel positions as those of para-phenylene, 4,4'-biphenylene , 1, 5-naphthalene and 2,6-naphthalene. More preferably, at least 99% of the amide bonds are para-oriented and more preferably 100% of the bonds are for targeting. Concrete examples of said para-aramid include aramides whose structures have a poly-para-oriented form or a form close to it, such as poly (para-phenyleneterephthalamide), poly (4,4'-benzanilide terephthalamide) polyamide (para-phenylene acid) 4,4'-biphenylenedicarboxylic acid) and polyamide of (para-phenyl-2,6-naphthalenedicarboxylic acid). Among these para-aramides, the most representative is poly (paraphenylene terephthalamide) (hereinafter PPTA abbreviated).

Examples of para-oriented aromatic diamines usable in the present invention include para-phenylenediamine, 4,4'-diaminobiphenyl, 2-methyl-para-phenylenediamine, 2-chloro-para-phenylenediamine, 2,6-naphthalene-diamine, 1.5- naphthalenediamine, and 4,4'-diaminobenzanilide. Examples of para-oriented aromatic dicarboxylic acid halides usable in the present invention include terephthaloyl chloride, 4,4'-dibenzoyl chloride, 2-chloroterephthaloyl chloride, 2,5-dichloroterephthaloyl chloride, 2-methylterephthaloyl chloride, chloride of 2,6-naphthalenedicarboxylic acid, and 1,5-naphthalenedicarboxylic acid chloride. Prior to this, PPTA was produced in polar amide salt / solvent systems in the following manner. Thus, PPTA is produced by carrying out a solution polymerization reaction in a polar amide solvent. PPTA is precipitated, washed with water and dried and once isolated as a polymer. Then, the polymer is dissolved in a solvent and converted into a PPTA fiber by the wet spinning process. In this step, concentrated sulfuric acid is used as the solvent for the spinning mass, since PPTA is not readily soluble in organic solvents. This spinning mass usually shows an optical anisotropy. Industrially, the fiber of PPTA is produced from a spinning mass using concentrated sulfuric acid as a solvent, - considering the performances as long fiber, in particular the strength and rigidity.

In accordance with the prior art process, a meta-aramid fibroid is made by beating a liquid suspension of the shaped structures by an interface forming process, by adding a solution of a polymer to a precipitator for the polymer, using a fibrizer, which is a rotor that generates shear, any method that applies sufficient shear stress on the polymer can also be used to make the para-aramid fibril films of this invention. In general, the methods for manufacturing the sharp skin of the invention comprise the steps: a. polymerizing a para-oriented aromatic diamine and a para-oriented aromatic dicarboxylic acid halide to an aramid polymer having only para-oriented bonds in a solvent mixture consisting of n-methylpyrrolidone or dimethylacetamide and calcium chloride or lithium chloride to obtain a mass in which the polymer dissolves in the solvent mixture and the polymer concentration is from 2 to 6% by weight, and b. converting the mass to a fibrous para-aramid film by using conventional methods known to make meta-aramid fibril. It should be mentioned that many polymerization processes are known to make para-aramid. However, none of these leads to a para-aramid fibril. Thus, EP 572002 describes a process that leads to pulp and fiber instead of fibril. This reference describes a different process than the present process, that is, the fibers are spun and then the pulp is produced in the common way when cutting the fiber to make short fiber, which is subjected to a refining process subsequent to this. US 2001/0006868 describes the manufacture of pieces of fiber but these contain non-para-oriented bonds (ie 3,4-diphenylether units). In US 6042941 the polymerization is carried out in sulfuric acid, in EP 302377 the polymerization is carried out in DMSO and also in US 4921900 no para-aramid fibrid is formed as explained above. In another embodiment of the invention, the polymerization is carried out such that at least part of the hydrochloric acid formed is neutralized to obtain a neutralized mass. In a particularly preferred embodiment the mass is converted to a para-aramid fibril film by: i. spinning the mass through a jet spinning nozzle to obtain a polymer stream, striking the polymer stream with a coagulant at an angle where the vector of the coagulant velocity perpendicular to the polymer stream is at least 5 m / s, preferably at least 10 m / s to coagulate the stream to fibrous para-aramid films, or ii. coagulate the mass by means of a rotor stator apparatus in which the polymer solution is applied through the rotor stator so that the polymer precipitates that precipitate are subjected to shear forces while in a deformable plastic stage. In the present invention 0.950-1.050 moles, preferably 0.980-1.030, more preferably 0.995-1.010 moles of para-oriented aromatic diamine is used for one mole of para-oriented aromatic carboxylic acid halide in a polar amide solvent in which 0.5 -4% by weight of alkali metal chloride or alkaline earth metal chloride is dissolved (preferably 1-3% by weight), with the concentration of para-amide obtained therefrom 2-6% by weight, more preferably 3-4.5% in weigh. In the present invention the polymerization temperature of para-aramid is -20 ° C to 70 ° C, preferably 0 ° C to 30 ° C, and more preferably 5 ° C to 25 ° C. In this temperature scale the dynamic viscosity is within the required scale and the fibride produced from it by spinning can have a sufficient degree of crystallization and degree of crystal orientation. An important feature of the present invention is that the polymerization reaction can first be improved and then stopped by neutralizing the polymer solution or solution forming the polymer by adding an inorganic base or strong organic base, preferably calcium oxide or lithium oxide. In this sense the terms "calcium oxide" and "lithium oxide" include calcium hydroxide and lithium hydroxide, respectively. This neutralization effects the removal of hydrogen chloride, which is formed during the polymerization reaction. The neutralization results in a drop in the dynamic viscosity with a factor of at least 3 (with respect to the corresponding non-neutralized solution). By mole of the amide group formed in the polycondensation reaction, after neutralization the chlorides are preferably present in an amount of 0.5-2.5 moles, more preferably in an amount of 0.7-1.4 moles. The total amount of chloride can originate from CaCl2, which is used in the solvent and from CaO, which is used as a neutralizing agent (base). If the calcium chloride content is too high or too low, the dynamic viscosity of the solution rises both to be suitable as a solution for spinning. Mass, and also the fibril film products obtained from it are essentially free of organic ions other than Ca2 +, L + and Cl. "The para-aramid liquid polymerization solution can be supplied with the aid of a pressure vessel to a Spinning pump for feeding a nozzle for spinning by 100-1000 μm jet to the fibrids The para-aramid liquid solution is spun through a spinning nozzle in a lower pressure zone In accordance with a preferred embodiment It performs jet spinning using a coagulating jet in the spinning nozzle, without using air to disperse the polymer stream.More preferably, the coagulant strikes the essentially perpendicular polymer stream. air at more than 1 bar, preferably 4-6 bar.The air is applied separately through a ring-shaped channel to the same area where urre the expansion of the air. Under the influence of the coagulant stream the liquid spinning solution is converted to fibril films. The coagulant is selected from water, mixtures of water, NMP and CaCl2, and any other suitable coagulant. Mixtures of NMP water and CaCl2 are preferred.

An object of the invention is to provide compositions comprising the aforementioned para-aramid fibril. Another object of the present invention is to make an improved paper by using compositions having at least 2% of the para-aramid fibril films of this invention. Preferably, at least 5%, more preferably at least 10% (by weight) of para-aramid fibril film is used in papermaking compositions. Other components and such compositions are pulp, flocculent, fiber, discontinuous fiber, fillers, inorganic fibers, and the like, which may contain polymer for and / or meta-aramide or any other polymer for papermaking; This and other objects are achieved by a process for making a para-aramid polymer solution comprising the steps of at least partially neutralizing the hydrochloric acid to obtain a solution wherein the dynamic viscosity is at least a factor of three less that the dynamic viscosity of the polymer solution without neutralization, and wherein the concentration of p-aramid in the solution is from 2 to 6% by weight. The neutralization can be carried out during or after the polymerization reaction. According to another embodiment of the invention, a neutralized non-fibrous polymer solution of para-aramid has been made in a mixture of NMP / CaCl2, NMP / LiCI, or DMAc / LiCI wherein the polymer has a relative viscosity? Re? > 2.2.

Depending on the polymer concentration the mass exhibits anisotropic or isotropic behavior. Preferably, the dynamic viscosity Δ dyn is less than 10 Pa.s, more preferably less than 5 Pa.s at a shear rate of 1000 s "1. Neutralization, if carried out, takes place during or preferably after Polymerize the monomers that make up the para-aramid The neutralizing agent is not present in the monomer solution before the polymerization has begun Neutralization reduces the dynamic viscosity by a factor of at least 3. The neutralizing polymer solution can used for direct fibrillation film spinning using a nozzle, contacting the polymer stream with a coagulant or pressurized air in a lower pressure zone where the polymer stream is interrupted and coagulated to fibril films. air the polymer stream must be hit by a coagulant (preferably a mixture of water, NMP, and CaC). an angle wherein the vector of the coagulant velocity perpendicular to the polymer stream is at least 5 m / s, preferably at least 10 m / s to coagulate the stream to para-aramid fibril films. The para-aramid polymer solution of the present invention exhibits a low dynamic viscosity at a temperature of up to about 60 ° C on the shear rate scale of 100-10,000 s "1. For that reason the polymer solution according to the invention, it can be spun at a temperature below 60 ° C, preferably at room temperature.Furthermore, the para-aramid mass of the present invention is free of an extra component such as pyridine and can be conveniently produced from the industrial point of view in which the production process can be simplified and the process is free from the problem of corrosion of the devices by concentrated sulfuric acid compared to the masses using concentrated sulfuric acid as a solvent. In the present invention, the polymer solution can be spun directly and the product can be made in a direct fibril film. in mind, so that the production process can be greatly simplified. A para-aramid paper having a very high paper strength (which is measured as a high stress index) is already obtained before drying the paper at! apply the para-aramid fibril films of the invention. Such papers show very low porosity and very low moisture content. The fibril films of the present invention are useful as a starting material for para-aramid paper, friction materials including automotive brakes, various packaging, electronic documents (for example for electronic purposes, since it contains very low amounts of ions compared to the para-aramid pulp made from sulfuric acid solutions), and the like. The present invention will now be explained by means of the following non-restrictive examples.The methods for testing and evaluation and judgment criteria used in the examples and comparative examples were as follows.

Test methods Relative viscosity The sample was dissolved in sulfuric acid (96%) at room temperature at a concentration of 0.25% (m / v). The flow time of the sample solution in sulfuric acid was measured at 25 ° C in a Ubbeiohde viscometer. Under identical conditions, the flow time of the solvent is measured in the same way. The viscosity ratio is then calculated as the ratio between the two flow times observed.

Dynamic viscosity Dynamic viscosity is measured using capillary rheometry at room temperature. When using the Powerlaw coefficient and the Rabinowitsch correction, the shear velocity in real wall and the viscosity are calculated.

Measurement of fiber length A fiber length measurement was performed using Pulp Expert ™ FS (from Metso). As length we used the average length (AL), the length weighted in length (LL), the length weighted in weight (WL). The subscript 0.25 means the corresponding value for particles with a length > 250 microns. The amount of fine particles was determined as the fraction of particles having a length-weighted length (LL) < 250 microns. That instrument needs to be calibrated with a sample with a known fiber length. The calibration is carried out with commercial pulp available as indicated in table 1.

TABLE 1 A Kevlar® 1 F539, Type 979 B Twaron® 1095, Load 315200, 24-01 -2003 C Twaron® 1099, Ser. No. 323518592, Art. No. 108692 Determination of specific surface area (SSA) The specific surface area (m2 / g) was determined using nitrogen adsorption using the BET specific surface area method, using a Gemini 2375 manufactured by Micromeretics. The wet pulp samples were dried at 120 ° C overnight, followed by nitrogen washing for at least one hour at 200 ° C.

Value CSF Tappi 227 Dispose 3g (dry weight) of pulp that has never dried in 11 water for 1000 cycles of blow in a blaster Lorentz and Wettre. You get a very open pulp. The value of Canadian drainage capacity (CSF) is measured and corrected for slight differences in pulp weight (Tappi 227).

Paper strength Hand sheets (70 g / m2) made of 100% fibril or 50% fibril material and 50% Twaron® 6 mm (Twaron ® 1000) fiber were made. The tension index (Nm / g) was measured in accordance with ASTM D828 and Tappi T494 om-96 on dry paper (120 ° C), where the sample width is 15 mm, the sample length 100 mm, and the test speed 10 mm / min at 21 ° C / 95% HA.

Optical anisotropy evaluation (liquid crystal state) Optical anisotropy is examined under a polarization microscope (bright image) and / or seen as opalescence during agitation.

EXAMPLE 1 Polymerization of para-phenyleneterephthalamide (PPTA) was carried out using a Drais 160 L reactor. After sufficient drying of the reactor, 63 I of NMP / CaCl 2 (N-methylpyrrolidone / calcium chloride) were added at a concentration of CaCl2 2.5% by weight. Subsequently, 1487 g of paraphenylenediamine (PPD) were added and dissolved at room temperature. Subsequently, the PPD solution was cooled to 10 ° C and 2772 g of TDC were added. After the addition of the TDC, the polymerization reaction continued for 45 min. Then the polymer solution was neutralized with a calcium oxide / NMP suspension (766 g of CaO in NMP). After the addition of the CaO suspension the polymer solution was stirred for at least another 15 min. This neutralization was carried out to eliminate hydrogen chloride (HCl), which is formed during polymerization. A gel-like polymer solution with a PTA content of 4.5% p and having a relative viscosity of 3.5 (in 0.25% H2SO4) was obtained. The obtained solution exhibited optical anisotropy and was stable for more than one month. The solution was diluted with NMP until a polymer concentration of 3.6% was obtained. The solution was spun through a jet spinning nozzle (spin hole 350 microns) at 5 kg / hour (room temperature). Water at 1400 l / hour was added through a ring-shaped channel at an angle in the direction of polymer flow. The water velocity was 14 m / s.

The fibrid was collected under a filter and was characterized as having a WL0.25 mm of 1.85 mm, final particle content of 18% and an SSA of 2.11 m2 / g with a CSF value of 330 ml. A paper was made that consisted of 100% fibrid that resulted in TI of 10.0 Nm / g.

EXAMPLE 2 The polymerization of para-phenylterephthalamide was carried out using a Drais 160L reactor. After drying the reactor sufficiently, 63 I of NMP / CaCl2 (N-methylpyrrolidone / calcium chloride) was added with a CaCl2 concentration of 2.5% by weight. Then, 1506 g of para-phenylenediamine (PPD) was added and dissolved at room temperature. After this the PPD solution was cooled to 10 ° C and 2808 g of TDC was added. After the addition of TDC, the polymerization reaction was continued for 45 min. The polymer solution was then neutralized with a calcium oxide / NMP suspension (776 g of CaO in NMP). After addition of the CaO suspension the polymer solution was stirred for at least another 15 min. This neutralization was carried out to remove the hydrogen chloride (HCl), which is formed during the polymerization. A gel-like polymer solution with a PPTA content of 4.5% p and having a relative viscosity of 3.2 (in 0.25% H2SO4) was obtained. The obtained solution showed optical anisotopy and was stable for more than one month. The solution was diluted with NMP until a polymer concentration of 3.6% was obtained. The solution was spun through a jet spinning nozzle at 4.3 kg / hour. The nozzle had a nozzle height of 350 μm. Air was blown through a ring-shaped channel with 5.9 Nm3 / h (normal cube per hour) (7 bar) perpendicular to the polymer flow, then water was added at 724 l / ha through a ring-shaped channel at an angle in the direction of the polymer stream. The water velocity was 16 m / s. The fibrid was collected through a filter and characterized by having a WL0.25 mm of 1.63 mm, fine particle content of 19% and an SSA of 3.6 m2 / g, CSF value of 215 ml.

EXAMPLE 3 The polymerization of para-phenyleneterephthalamide was carried out using a Drais reactor of 2.5 m 3. After the reactor was sufficiently dried, 1140 I of NMO / CaCl2 (N-methylpyrrolidone / calcium chloride) was added with a CaCl2 concentration of 2.5% p. Subsequently, 27.50 kg of para-phenylendinamine (PPD) was added and dissolved at room temperature. After this the PPD solution was cooled to 5 ° C and 51.10 kg of TDC were added. After addition of TDC the polymerization reaction continued for 45 min. Then the polymer solution was neutralized with a suspension of calcium oxide / NMP (14.10 kg of CaO in 28 I NMP). After the addition of the CaO suspension the polymer solution was stirred for at least another 15 min. This neutralization was carried out to eliminate the hydrogen chloride (HCi), which is formed during the polymerization. A gel-like polymer solution having a PPTA content of 4.5% p and having a relative viscosity of 2.2 (in 0.25% H2SO4) was obtained. The solution was diluted with NMP until a polymer concentration of 3.1% was obtained. The obtained solution showed optical anisotropy and was stable for more than one month. The solution was spun through a jet spinning nozzle (hole 350 microns) at 25 kg / hour. Water was added through a ring-shaped channel flowing perpendicular to the polymer flow at 840 l / h. The water velocity was 30 m / s. The fibrid was collected on a filter and characterized by having a WL0.25 mm, fine particle content of 28% and a 1.09 mm, SSA of 1.76 m2 / g and a CSF value of 70 ml. A paper was made that consisted of 100% fibrid resulting in TI of 24 Nm / g. In the case that 50% Twaron® 1000 6 mm fiber and 50% of fibrids were used, an IT paper of 38 Nm / g was obtained.

The polymerization of para-phenyleneterephthalamide was carried out using a Drais 2.5 m3 reactor. After the reactor was sufficiently dry, 1145 I of NMP / CaCl2 (N-methylpyrrolidone / caycinium chloride) with a CaCl2 concentration of 2.5% p. Were added to the reactor. Subsequently, 27.10 kg of para-phenylenediamine (PPD) was added and dissolved at room temperature. After this the PPD solution was cooled to 5 ° C and 50.35 kg of TDC were added. After the addition of TDC the polymerization reaction continued for 45 min. Then the polymer solution was neutralized with a calcium oxide / NMP suspension (13.90 kg of CaO in 28 I NMP). After the addition of the CaO suspension the polymer solution was stirred for at least another 15 min. The neutralization was carried out to remove the hydrogen chloride (HCl) that is formed during the polymerization. A gel-like polymer solution having a PPTA content of 4.5% p and having a relative viscosity of 2.0 (in 0.25% H2SO4) was obtained. The solution was diluted with NMP until a polymer concentration of 3.6% was obtained. The obtained solution exhibited optical anisotropy and was stable for more than one month. Fibers were spun with different lengths using a four-hole jet spinning nozzle (350 μm) where NMP / CaCl2 / water (30% p / 1.5% p / 68.5% p) flows through perpendicular ring-shaped channels to the polymer flow. When changing the speed of coagulants (27-53 m / s) the length of the fibrids is changed. Papers were made from 50% Twaron® 1000 6 mm fiber and 50% fibrid. See Table 2 for characteristics of fibril and paper.

TABLE 2 EXAMPLE 7 A solution of PPTA in NMP / CaCl2 was diluted 3.1% (same solution as in Example 3). The relative viscosity was 2.2. The solution was added to a rotor stator coagulator. The data of the fibers 7a and 7b (which have the rotor speeds indicated in the table) are summarized in Table 3. A role was made that consisted of 100% fibril that resulted in IT as indicated in Table 3.

TABLE 3 Coagulator: Unitika Flow polymer solution 60 g / hr. Coagulant flow: 1200 L / h Coagulant: water / NMP (20%) / CaCl2 (1%) Rotor speed: Ex 7a 3000 rpm Ex 7b 5400 rpm

Claims (11)

NOVELTY OF THE INVENTION CLAIMS

1. - A film of para-aramid fibrid, where at least 95% of the polymer bonds are para-oriented.

2. The fibril film according to claim 1, further characterized in that the polymer is poii (para-phenyleneterephthalamide).

3. The fibril film according to claim 1 or 2, further characterized in that the fibril film has an average length of 0.2-2 mm and a width of 10-500 μm.

4. The fibril film according to any of claims 1-3, further characterized in that it comprises less than 40%, preferably less than 30% fine particles, wherein the fine particles are defined as particles having a length-weighted length (LL) less than 250 μm.

5. The fibrid film according to any of claims 1-4, further characterized in that it is essentially free of inorganic ions other than Ca2 +, Li + and CI ions. "

6. A composition comprising the fibril film for - Aramid of any of claims 1-5 - A paper made of constituents comprising at least 2% by weight, preferably 5% by weight, more preferably at least 10% by weight of the fibril film for - Aramid of any of claims 1-5 - A method for manufacturing the fibril film according to any of claims 1-5, comprising the steps of: a) polymerizing a para-oriented aromatic diamine and a Aromatic dicarboxylic acid halide para-oriented to an aramid polymer having only para-oriented bonds in a solvent mixture consisting of N-methylpyrrolidone or dimethylacetamide and calcium chloride or lithium chloride to obtain a mass in which the polymer is dissolved in the solvent mixture and the polymer concentration is 2 to 6% by weight, and b) to convert the mass to a para-aramid fibril film by using known methods for making a fibril meta-aramid. 9. The method according to claim 8, further characterized in that at least part of the hydrochloric acid formed is neutralized to obtain a neutralized mass. 10. The method according to claim 8 or 9, further characterized in that the mass is converted to a para-aramid fibril film at: i. spinning the mass through a jet spinning nozzle to obtain a polymer stream, striking the polymer stream with a coagulant at an angle where the vector of the coagulant velocity perpendicular to the polymer stream is at least 5 m / s, preferably at least 10 m / s to coagulate the stream to fibrous para-aramid films, or ii. coagulate the mass by means of a rotor stator apparatus wherein the polymer solution is applied through the stator in the rotor so that the precipitating polymer bribers are subjected to shear forces while in a deformable plastic stage. 11. The method according to claim 9 or 10, further characterized in that the? Rel (relative viscosity) of para-aramid polymer is between 2.0 and 5.0.