HK1097014B - Para-aramid fibrid film - Google Patents

Description

Para-aramid fibrid film

The present invention relates to a para-aramid fibrid film (fibrid film), a composition comprising the fibrid film, a method for producing the fibrid film, and paper comprising the fibrid film.

Aramid fibrids are known in the art. For example, the preparation of fibrids of aramid polymers containing meta-bonds is disclosed in US 3,756,908. These fibrids can be designed as meta-aramid fibrids and can be used in the papermaking process, preferably in combination with meta-or para-aramid pulp and meta-or para-aramid floe.

Fibrids are small, non-particulate, non-rigid fibrous or film-like particles where in the film one of their dimensions is in the micrometer range and in the fibers the two dimensions are in the micrometer range. The term "fibrids" is well known in the art and is clearly understood by those skilled in the art. The skilled reader may further refer to US 2,999,788, wherein a precise definition is given, wherein the term "fibrids" is further defined as-fibrid particles must have the ability to form handsheets (watercrafts). It should further have the ability to incorporate a significant weight of staple fibers. The term "fibrid film" as used in the present invention always complies with the above definition for film-like particles, wherein the canadian freeness number is from 40 to 790. The term "para" relates to the aramid bonds of the polymer constituting the fibrids.

In addition to US 3,756,908, there are a number of other references which describe meta-aramid fibrids. However, no reference is known to describe para-aramid fibrids meeting the above definition.Unfortunately, the term "para-aramid fibrids" is sometimes used incorrectly to describe pulp that is fibrillated and does not have a film-like structure, nor does it entirely meet the above requirements. Thus, for example, US 6,309,510 mentions KevlarAnd (5) precipitating the fibers. Kevlar (R)Is a trademark of Dupont's para-aramid. However, the material is highly fibrillated and is therefore by definition a pulp.

Another example of misuse of the term "fibrids" can be found in WO 91/00272, in which example 8 mentions KevlarPPTA fibrids. From the context of this example and its title, it is clear that fibers are used instead of fibrids. Note also that the trade name KevlarThere were no commercially available fibrids. Us patent 4,921,900 is the only reference that does not immediately see if the para-aramid fibrids mentioned are indeed fibrids. However, when the examples of this reference are repeated, it appears that the polymerization step does not produce a clear solution, and that solidification of the solution produces polymer particles. These particles do not meet the above definition of fibrids. Furthermore, the resulting particles contain a high content (60%) of fines.

Although para-aramid fibrid membranes meeting the above definition have not been described, we believe that these fibrids have advantageous properties when used in place of the commonly used meta-aramid fibrids. In particular, improved paper properties are expected to be related to strength, porosity, high temperature resistance and moisture content. It is therefore an object of the present invention to obtain a process for the preparation of para-aramid fibrid film, as well as the fibrid film produced and the products made therefrom.

To this end, the invention relates to a para-aramid fibrid film wherein at least 95% of the bonds of the polymer are para-oriented.

One dimension of the fibrid film is in the micrometer range, while the length and width are much larger, preferably with an average length of 0.2-2 millimeters and a width of 10-500 micrometers.

Further preferred are fibrid films containing less than 40%, preferably less than 30% fines, where fines refer to particles having a length weighted length (LL) of less than 250 microns.

Para-oriented aramid (aromatic amide) is a polycondensate of a para-oriented aromatic diamine and a para-oriented aromatic dicarboxylic acid halide (hereinafter referred to as "para-aramid") and has heretofore been known to be used in various fields of fibers, pulp and the like because of its high strength, high elastic modulus and high heat resistance.

The term "para-aramid" as used in the present invention means a substance obtained by polycondensation of a para-oriented aromatic diamine and a para-oriented aromatic dicarboxylic acid halide, at least 95% of amide bonds of the repeating units of which are located at para-oriented or nearly para-oriented opposite positions of the aromatic ring, i.e., at coaxially or parallel aligned positions as in para-phenylene, 4' -biphenylene, 1, 5-naphthylene and 2, 6-naphthylene. More preferably, at least 99% of the amide linkages are para-oriented, and most preferably, 100% of the linkages are para-oriented.

Specific examples of the para-aramid include aromatic polyamides having a structure in a poly-para-oriented form or a form close thereto, such as poly (p-phenylene terephthalamide), poly (4, 4 '-benzanilide terephthalamide), poly (p-phenylene-4, 4' -biphenylenedicarboxamide), and poly (p-phenylene-2, 6-naphthalenedicarboxamide). Of these para-aramids, poly (p-phenylene terephthalamide) (hereinafter abbreviated to PPTA) is most representative.

Examples of para-oriented aromatic diamines useful in the present invention include p-phenylenediamine, 4 '-diaminobiphenyl, 2-methyl-p-phenylenediamine, 2-chloro-p-phenylenediamine, 2, 6-naphthalenediamine, 1, 5-naphthalenediamine, and 4, 4' -diaminobenzanilide.

Examples of para-oriented aromatic dicarboxylic acid halides useful in the present invention include terephthaloyl chloride, 4' -bibenzoyl chloride, 2-chloroterephthaloyl chloride, 2, 5-dichloroterephthaloyl chloride, 2-methyl terephthaloyl chloride, 2, 6-naphthalenedicarboxylic acid chloride and 1, 5-naphthalenedicarboxylic acid chloride.

To date, PPTA has been made in a polar amide solvent/salt system in the following manner. For example, PPTA is made by solution polymerization in a polar amide solvent. The PPTA precipitated, washed with water and dried and isolated once as a polymer. The polymer is then dissolved in a solvent and made into PPTA fibers by wet spinning. In this step, concentrated sulfuric acid is used as a solvent for the spinning dope, because PPTA is not readily soluble in organic solvents. The dope usually exhibits optical anisotropy.

Industrially, PPTA fibers are produced from a spinning dope using concentrated sulfuric acid as a solvent, in consideration of properties as long fibers, particularly strength and rigidity.

The meta-aramid fibrids of the present invention are produced according to the conventional method by beating a liquid suspension of a shaped structure by an interfacial shaping method, by adding a polymer solution to a precipitant for the polymer, by using a fibrid-forming machine (a fibrid-generator, which is a rotor that generates shear), and the para-aramid fibrids of the present invention can also be produced by any method that applies sufficient shear to the polymer.

Generally, the method of making a fibrid film of the invention comprises the steps of:

a. polymerizing a para-oriented aromatic diamine and a para-oriented aromatic dicarboxylic acid halide in a solvent mixture consisting of N-methylpyrrolidone or dimethylacetamide and calcium chloride or lithium chloride to form an aramid polymer containing only para-oriented bonds, thereby obtaining a dope, wherein the polymer is dissolved in the solvent mixture and the polymer concentration is 2 to 6% by weight, and

b. the dope is converted to a para-aramid fibrid film using known conventional methods for making meta-aramid fibrids.

It should be noted that many polymerization processes for making para-aramid are known. However, none of these produced para-aramid fibrids. For example, EP 572002 describes a process which produces pulp and fibers rather than fibrids. This reference describes a different process than that of the present invention, namely spinning into fibers and then making pulp by cutting the fibers into staple fibers in the usual manner, which is then subjected to a refining process. US 2001/0006868 describes the production of chopped fibres, but these contain bonds that are not in the para-orientation (i.e. 3, 4' -diphenyl ether units). Polymerization in sulfuric acid in US 6042941, polymerization in DMSO in EP 302377 and also formation of para-aramid fibrids in US4921900 as previously described.

In another embodiment of the present invention, the polymerization is carried out such that at least a portion of the hydrochloric acid produced is neutralized to obtain a neutralized spin dope.

In a particularly preferred embodiment, the dope is converted to a para-aramid fibrid film as follows:

i. spinning the dope through a jet spinning nozzle to obtain a polymer stream, impinging the polymer stream with a coagulant at an angle, wherein the coagulant velocity vector perpendicular to the polymer stream is at least 5 m/s, preferably at least 10 m/s, thereby coagulating the polymer stream into a para-aramid fibrid film, or

Coagulating the dope using a rotor stator device, wherein the polymer solution is applied by the rotor on the stator, thereby applying shear forces to the precipitated polymer fibrids while they are in a plastically deformable stage.

In the present invention, the para-oriented aromatic diamine is used in an amount of 0.950 to 1.050 mol, preferably 0.980 to 1.030, more preferably 0.995 to 1.010 mol, per 1 mol of the para-oriented aromatic carboxylic acid halide in the polar amide solvent in which 0.5 to 4% by weight of an alkali metal chloride or an alkaline earth metal chloride is dissolved, preferably 1 to 3% by weight, so that the concentration of the resulting para-aromatic polyamide is 2 to 6% by weight, more preferably 3 to 4.5% by weight. In the present invention, the polymerization temperature of the para-aramid is-20 ℃ to 70 ℃, preferably 0 ℃ to 30 ℃, more preferably 5 ℃ to 25 ℃. In this temperature range, the dynamic viscosity is in a desired range, and the fibrids produced therefrom by spinning may have a sufficient degree of crystallinity and a sufficient degree of crystal orientation.

An important feature of the present invention is that the polymerization reaction can be first enhanced and thereafter stopped as follows: the polymer solution or the solution forming the polymer is neutralized by adding an inorganic or strong organic base, preferably calcium oxide or lithium oxide. In this regard, the terms "calcium oxide" and "lithium oxide" include calcium hydroxide and lithium hydroxide, respectively. This neutralization removes hydrogen chloride formed during the polymerization reaction. Neutralization results in a reduction in dynamic viscosity by a factor of at least 3 (relative to the unneutralized corresponding solution). The chloride is preferably present in an amount of 0.5 to 2.5 moles, more preferably 0.7 to 1.4 moles, per mole of amide group formed in the polycondensation reaction after neutralization. The total amount of chloride may be derived from CaCl used in the solvent₂And CaO used as a neutralizing agent (alkali). If the calcium chloride content is too high or too low, the dynamic viscosity of the solution is excessively increased and thus it is not suitable as a spinning solution. The spinning dope, and the fibrid film product obtained therefrom are substantially free of Ca²⁺、Li⁺And Cl^-Inorganic ions other than ions.

The liquid para-aramid polymerization solution may be supplied to a spinning pump via a pressure vessel to be introduced into a nozzle of 100-1000 μm for jet spinning to produce fibrids. The liquid para-aramid solution is spun through a spinneret into a zone of lower pressure. According to one embodiment of the invention, the use in spinning nozzlesThe coagulation jets perform jet spinning without using air to disperse the polymer stream. More preferably, the coagulant impinges the polymer stream substantially vertically. In another embodiment, air jet spinning at over 1 bar, preferably 4-6 bar, is used. Air is separately fed through the annular channel into the same zone where it expands. The liquid spinning dope is converted into a fibrid film under the influence of a coagulant stream. The coagulant is selected from water, NMP and CaCl₂Mixtures of (a) and any other suitable coagulating agent. Preferred are water, NMP and CaCl₂A mixture of (a).

It is an object of the present invention to provide a composition comprising the above para-aramid fibrids.

It is another object of the present invention to produce improved paper using a composition containing at least 2% of the para-aramid fibrid film of the present invention. Preferably, at least 5%, more preferably at least 10% (by weight) of the para-aramid fibrid film is used in the papermaking composition. Other components in these compositions are conventional pulp, floe, fiber, staple fiber, filler, inorganic fiber, etc., which may contain para and/or meta aramid polymer, or any other suitable papermaking polymer.

These and other objects can be achieved by a process for producing a para-aramid polymer solution, comprising the step of at least partially neutralizing hydrochloric acid to obtain a solution, wherein the dynamic viscosity is two-thirds lower than that of the unneutralized polymer solution, and wherein the concentration of para-aramid in the solution is from 2 to 6% by weight. Neutralization may be carried out during or after the polymerization reaction.

According to another embodiment of the present invention, para-aramid has been made in NMP/CaCl₂Non-fiber neutralized polymer solution in NMP/LiCl or DMAc/LiCl mixture, wherein the polymer solution has η_relRelative viscosity > 2.2.

Depending on the polymer concentration, the dope exhibits anisotropySexual or isotropic properties. Preferably, at 1000 s^-1Dynamic viscosity at shear rate of_dynLess than 10pa.s, more preferably less than 5 pa.s. If neutralization is performed, it is performed during or preferably after the polymerization of the monomers to form the para-aramid. No neutralizing agent was present in the monomer solution before the start of polymerization. Neutralization reduces the dynamic viscosity by at least two thirds. The neutralized polymer solution can be used for direct fibrid film spinning using a nozzle, where the polymer stream is contacted with a coagulant or compressed air in a region of lower pressure, where the polymer stream is broken up and coagulated into a fibrid film. When air is used, a coagulant (preferably water, NMP and CaCl) should be used thereafter₂The mixture of (a) and (b) impact the polymer stream. The coagulation is carried out at an angle wherein the coagulant velocity vector perpendicular to the polymer stream is at least 5 m/s, preferably at least 10 m/s, thereby coagulating the polymer stream into a para-aramid fibrid film.

The para-aramid polymer solution of the present invention is at a temperature of up to about 60 ℃ for 10,000 seconds^-1Exhibit low dynamic viscosity over a range of shear rates. Thus, the polymer solution of the invention can be spun at a temperature below 60 ℃, preferably at room temperature. Further, the aramid spinning dope of the present invention does not contain an additional component such as pyridine and can be advantageously produced from an industrial point of view because the production process can be simplified and the process is free from the problem of corrosion of equipment by concentrated sulfuric acid as compared with the existing spinning dope using concentrated sulfuric acid as a solvent.

Further, according to the method of the present invention, the polymer solution can be directly spun, and the product can be made into a fibrid film, thereby greatly simplifying the manufacturing process.

Using the para-aramid fibrid film of the present invention, para-aramid paper having very high paper strength (measured at high tensile index) is obtained before the paper is dried. These papers further exhibit very low porosity and low equilibrium moisture content. The fibrid film of the present invention can be used as raw materials for para-aramid paper, friction materials (including automobile brakes), various gaskets, E-paper (e.g., for electronic use because it contains a very low amount of ions compared to para-aramid pulp made from a sulfuric acid solution), and the like.

The invention will now be illustrated by the following non-limiting examples.

The test and evaluation methods and judgment standards used in the examples and comparative examples are as follows.

Test method

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 in an Ubbelohde viscometer at 25 ℃. Under the same conditions, the flow time of the solvent was measured. The viscosity ratio was then calculated as the ratio between the two observed flow times.

Dynamic viscosity

Dynamic viscosity was measured at room temperature using capillary rheometry. The actual wall shear rate and viscosity were calculated using the power law coefficients and the Rabinowitsch correction.

Fiber length measurement

Using Pulp Expert^TMFS (ex Metso) fiber length measurements were performed. As the length, an Average Length (AL), a length-weighted length (LL), and a weight-Weighted Length (WL) are used. Subscript 0.25 refers to the individual values for particles > 250 microns in length. The amount of fines refers to the fraction of particles having a length weighted length (LL) < 250 microns. The instrument needs to be calibrated with a sample of known fiber length. Calibration was performed with the commercially available pulp shown in table 1.

TABLE 1

A Kevlar1F539, type 979

B Twaron1095，Charge 315200，24-01-2003

C Twaron1099，Ser.No.323518592，Art.No.108692

Specific Surface Area (SSA) determination

The specific surface area (square meter/gram) was measured by the BET surface area method using nitrogen adsorption using Gemini 2375 manufactured by Micromeretics. The wet pulp sample was dried at 120 ℃ overnight and then purged with nitrogen at 200 ℃ for at least 1 hour.

CSF value Tappi 227

During 1000 beatings in a Lorentz and Wettre disintegrator, 3 g (dry weight) of pulp from the undried pulp were dispersed in 1 l of water. A fully opened pulp is obtained. Canadian Standard Freeness (CSF) values were measured and corrected for slight differences in pulp weight (Tappi 227).

Strength of paper

From 100% fibrid material or from 50% fibrid and 50% Twaron6 mm fibre (Twaron)1000) Making handsheets. Tensile index (Nm/g) was measured on dry paper (120 ℃ C.) according to ASTM D828 and Tappi T494 om-96, with a sample width of 15 mm, a sample length of 100 mm, and a test speed of 10 mm/min at 21 ℃/65% relative humidityThe conditions of (1).

Optical anisotropy evaluation (liquid Crystal State)

The optical anisotropy (bright image) was evaluated under a polarizing microscope and/or observed as opalescence during stirring.

Example 1

Polymerization of p-phenylene terephthalamide (PPTA) was carried out using a 160 liter Drais reactor. After the reactor was sufficiently dried, 63 liters of CaCl having 2.5 wt.% were added to the reactor₂Concentration of NMP/CaCl₂(N-methylpyrrolidone/calcium chloride). Then 1487 g of p-phenylenediamine (PPD) were added and dissolved at room temperature. Thereafter the PPD solution was cooled to 10 ℃ and 2772 g of TDC were added. After addition of TDC, the polymerization reaction was continued for 45 minutes. The polymer solution was then neutralized with a calcium oxide/NMP slurry (776 grams CaO in NMP). After the addition of the CaO slurry, the polymer solution was stirred for at least 15 minutes. This neutralization is carried out to remove hydrogen chloride (HCl) formed during the polymerization. A PPTA content of 4.5% by weight and a relative viscosity of 3.5 (at 0.25% H) was obtained₂SO₄In (b) is added. The resulting solution exhibits optical anisotropy and is 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 spinneret (350 micron orifice) at 5 kg/hour (room temperature). Water was added at 1400 l/h through the annular channel at an angle to the direction of polymer flow. The water velocity was 14 m/s. Collecting the fibrids on a filter, characterized by having a WL of 1.85 mm_0.25Fine content of 18%, SSA of 2.11 m/g, CSF value of 330 ml. Paper containing 100% fibrids was made, yielding a TI of 10.0 Nm/g.

Example 2

Polymerization of p-phenylene terephthalamide was carried out using a 160 liter Drais reactor. After the reactor had been sufficiently dried, 63 liters of CaCl having 2.5% by weight were charged into the reactor₂Concentration of NMP/CaCl₂(N-methylpyrrolidone/calcium chloride). Then 1506 g of p-phenylenediamine (PPD) was added and dissolved at room temperature. Thereafter the PPD solution was cooled to 10 ℃ and 2808 g of TDC were added. After addition of TDC, the polymerization reaction was continued for 45 minutes. The polymer solution was then neutralized with a calcium oxide/NMP slurry (776 grams CaO in NMP). After the addition of the CaO slurry, the polymer solution was stirred for at least 15 minutes. This neutralization is carried out to remove hydrogen chloride (HCl) formed during the polymerization. A PPTA content of 4.5% by weight and a relative viscosity of 3.2 (at 0.25% H) was obtained₂SO₄In (b) is added. The resulting solution exhibits optical anisotropy and is 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 spinneret at 4.3 kg/h. The nozzle had a spinning head of 350 microns. Perpendicular to the polymer flow through the annular passage at 5.9Nm³Air was blown in at/h (normal cubic/hour). Water was thereafter added at 724 l/h through the annular channel at an angle to the polymer flow direction. The water velocity was 16 m/s. Collecting the fibrids on a filter, characterized by having a WL of 1.63 mm_0.25Fine content of 19%, SSA of 3.6 m/g, CSF value of 215 ml.

Example 3

Polymerization of p-phenylene terephthalamide was carried out using a 2.5 cubic meter Drais reactor. After the reactor had been sufficiently dried, 1140 liters of CaCl having 2.5 wt.% were charged into the reactor₂Concentration of NMP/CaCl₂(N-methylpyrrolidone/calcium chloride). Then, 27.50 kg of p-phenylenediamine (PPD) was added at room temperature and dissolved. Thereafter the PPD solution was cooled to 5 ℃ and 51.10 kg of TDC were added. After addition of TDC, the polymerization reaction was continued for 45 minutes. The polymer solution was then neutralized with a calcium oxide/NMP slurry (14.10 kg CaO in 28L NMP). After the addition of the CaO slurry, the polymer solution was stirred for at least 15 minutes. This neutralization is carried out to remove hydrogen chloride (HCl) formed during the polymerization. A PPTA content of 4.5% by weight and a relative viscosity of 2.2 (at 0.25% H) was obtained₂SO₄In (b) is added. The solution was diluted with NMP until a polymer concentration of 3.1% was obtained. The resulting solution exhibits optical anisotropy and is stable for more than one month.

The solution was spun through a jet spinneret (350 micron hole) at 25 kg/h. Water was added through the annular channel at 840 litres per hour perpendicular to the polymer flow. The water velocity was 30 m/s. Collecting the fibrids on a filter, characterized by having a WL of 1.09 mm_0.25Fine content of 28%, SSA of 1.76 m/g, CSF value of 70 ml. Paper containing 100% fibrids was made, yielding a TI of 24 Nm/g. In the case of using 50% TwaronWith 10006 mm fibres and 50% fibrids a paper with a TI of 38Nm/g is obtained.

Examples 4, 5 and 6

Using 2.5 cubicThe MiDrais reactor was used to polymerize p-phenylene terephthalamide. After the reactor was sufficiently dried, 1145 liters of CaCl having 2.5 wt.% were charged into the reactor₂Concentration of NMP/CaCl₂(N-methylpyrrolidone/calcium chloride). Then, 27.10 kg of p-phenylenediamine (PPD) was added at room temperature and dissolved. Thereafter, the PPD solution was cooled to 5 ℃ and 50.35 kg of TDC was added. After addition of TDC, the polymerization reaction was continued for 45 minutes. The polymer solution was then neutralized with a calcium oxide/NMP slurry (13.90 kg CaO in 28L NMP). After the addition of the CaO slurry, the polymer solution was stirred for at least 15 minutes. This neutralization is carried out to remove hydrogen chloride (HCl) formed during the polymerization. A PPTA content of 4.5% by weight and a relative viscosity of 2.0 (at 0.25% H) was obtained₂SO₄In (b) is added. The solution was diluted with NMP until a polymer concentration of 3.6% was obtained. The resulting solution exhibits optical anisotropy and is stable for more than one month.

Different lengths of fibrids were spun using a 4-hole (350) micron jet spinneret in which NMP/CaCl was spun₂Water (30 wt%/1.5 wt%/68.5 wt%) was passed through an annular channel perpendicular to the polymer flow. The length of the fibrids was varied by varying the coagulant speed (27-53 m/s). From 50% Twaron10006 mm fiber and 50% fibrid. See table 2 for fibrid and paper properties.

Example 7

Will be in NMP/CaCl₂The PPTA solution in (1) was diluted to 3.1% (same solution as in example 1). The relative viscosity was 2.2. The solution was added to a rotor stator condenser. The data for the fibrids 7a and 7b (with the rotor speeds shown in the table) are summarized in table 3. Paper containing 100% fibrids was made, yielding TI as shown in table 3.

TABLE 3

A condenser: unitika

Flow rate of polymer solution: 60 g/h

Flow rate of coagulant: 1200 liters/hour

A coagulant: Water/NMP (20%)/CaCl 2 (1%)

Rotor speed: example 7a 3000rpm

Example 7b 5400rpm

Claims (14)

1. Para-aramid film-like fibrid particles characterized in that the para-aramid film-like fibrid particles are small, non-granular, non-rigid film-like particles wherein one of their dimensions is in the micrometer scale, which have the ability to form handsheets and a canadian freeness of 40 to 790, and the para-aramid of the para-aramid film-like fibrid particles is a condensation polymer of a para-oriented aromatic diamine and a para-oriented aromatic dicarboxylic acid halide, the repeating units of which have amide linkages and at least 95% of the amide linkages of the condensation polymer are in the para-oriented position of the aromatic ring.

2. The para-aramid film-like fibrid particle of claim 1 wherein the polymer is poly (p-phenylene terephthalamide).

3. The para-aramid film-like fibrid particles of claim 1 or 2 wherein the film-like fibrid particles have an average length of 0.2 to 2 mm and a width of 10 to 500 microns.

4. Para-aramid film-like fibrid particles of any one of claims 1-3 comprising less than 40% fines, wherein fines refers to particles having a length weighted length of less than 250 microns.

5. The para-aramid film-like fibrid particles of claim 4 comprising less than 30% fines.

6. The para-aramid film-like fibrid particles of any one of claims 1 to 5, which is substantially free of Ca²⁺、Li⁺And Cl^-Inorganic ions other than ions.

7. A composition comprising the para-aramid film-like fibrid particles of any one of claims 1-6.

8. Paper made from the following components: comprising at least 2 wt% of the para-aramid film-like fibrid particles of any one of claims 1-6.

9. Paper according to claim 8 made from a composition comprising at least 5 wt% of para-aramid film-like fibrid particles according to any one of claims 1-6.

10. Paper according to claim 8 made from a composition comprising at least 10 wt% of para-aramid film-like fibrid particles according to any one of claims 1-6.

11. A method for producing the para-aramid film-like fibrid particles of any one of claims 1 to 6, comprising the steps of:

a. polymerizing a para-oriented aromatic diamine and a para-oriented aromatic dicarboxylic acid halide in a solvent mixture consisting of N-methylpyrrolidone or dimethylacetamide and calcium chloride or lithium chloride to form an aramid polymer containing only para-oriented bonds, thereby obtaining a dope, wherein the polymer is dissolved in the solvent mixture and the polymer concentration is 2 to 6% by weight, and

b. the dope is converted to para-aramid film-like fibrid particles using known conventional methods for making meta-aramid fibrids.

12. The process according to claim 11, wherein at least a portion of the hydrochloric acid produced is neutralized to obtain a neutralized spin dope.

13. The process according to claim 11 or 12, wherein the dope is converted into para-aramid film-like fibrid particles by:

i. spinning the dope through a jet spinning nozzle to obtain a polymer stream, impinging the polymer stream with a coagulant at an angle, wherein the coagulant velocity vector perpendicular to the polymer stream is at least 5 m/s, preferably at least 10 m/s, thereby coagulating the polymer stream into para-aramid film-like fibrid particles, or

Coagulating the dope using a rotor stator device, wherein the polymer solution is applied by the rotor on the stator, thereby applying shear forces to the precipitated polymer fibrids while they are in a plastically deformable stage.

14. The process according to claim 12 or 13, wherein the para-aramid polymer has a relative viscosity η rel comprised between 2.0 and 5.0.