Para-aramid fibrid film
A para-aramid fibrid film is disclosed that has at least 95% of the bonds of the polymer are para-oriented. A method for making said para-aramid fibrid film by (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 mixture of solvents consisting of N-methylpyrrolidone or dimethylacetamide and calcium chloride or lithium chloride to obtain a dope wherein the polymer is dissolved in the mixture of solvents and the polymer concentration is 2 to 6 wt. %, and (b) converting the dope to para-aramid fibrid film is also described.
1. A para-aramid fibrid film-like particle, wherein at least 95% of the bonds of aramid of the para-aramid fibrid film-like particle are para-oriented, and, and wherein the para-aramid fibrid film-like particle is obtained by
polymerizing a para-oriented aromatic diamine and a para-oriented aromatic dicarboxylic acid halide at 20° C. to 70° C. in a polar amide solvent, in which 0.5-4 wt. % of alkali metal chloride or alkaline earth metal chloride is dissolved, using 0.950-1.050 mol of the para-oriented aromatic diamine per mol of the para-oriented aromatic dicarboxylic acid halide, to obtain a dope of 2-6 wt. % of an aramid polymer having at least 95% para-oriented bonds; and
converting the dope to the para-aramid fibrid film-like particle.
2. The para-aramid fibrid film-like particle of claim 1 , wherein the aramid is poly(para-phenyleneterephthalamide).
3. The para-aramid fibrid film-like particle of claim 1 , wherein the fibrid film-like particle has an average length of 0.2-2 mm and a width of 10-500 μm.
4. A composition comprising the para-aramid fibrid film-like particle of claim 1 and between about 0% to 40% of fines, wherein fines are defined as particles having a length weighted length (LL) less than 250 μm.
5. The para-aramid fibrid film-like particle of claim 1 , wherein the fibrid film-like particle is substantially free from inorganic ions other than Ca 2+ , Li + and Cl − ions.
6. A composition comprising the para-aramid fibrid film-like particle of claim 1 .
7. A paper made of constituents comprising at least 2 wt. % of the para-aramid fibrid film-like particle of claim 1 .
8. A method of manufacture of the para-aramid fibrid film-like particle of claim 1 , comprising:
polymerizing a para-oriented aromatic diamine and a para-oriented aromatic dicarboxylic acid halide to an aramid having at least 95% para-oriented bonds in a mixture of solvents consisting of N-methylpyrrolidone or dimethylacetamide and calcium chloride or lithium chloride to obtain a dope wherein the aramid is dissolved in the mixture of solvents and the aramid concentration is 2 to 6 wt. %, and
converting the dope to para-aramid fibrid film-like particles.
9. The method according to claim 8 wherein at least part of the hydrochloric acid formed in the method is neutralized to obtain a neutralized dope.
10. The method according to claim 8 wherein the dope is converted to para-aramid fibrid film-like particles by:
spinning the dope through a jet spin nozzle to obtain an aramid stream, hitting the aramid stream with a coagulant at an angle wherein the vector of the coagulant velocity perpendicular to the aramid stream is at least 5 m/s to coagulate the stream to para-aramid fibrid film-like particles, or
coagulating the dope by means of a rotor stator apparatus in which the aramid solution is applied through the stator on the rotor so that precipitating para-aramid fibrid film-like particles are subjected to shear forces while they are in a plastic deformable stage.
11. The method according to claim 9 wherein the ηrel (relative viscosity) of the para-aramid is between 2.0 and 5.0.
12. A composition comprising the para-aramid fibrid film-like particle of claim 1 and between about 0% to 30% of fines, wherein fines are defined as particles having a length weighted length (LL) less than 250 μm.
13. A paper made of constituents comprising at least 5 wt. % of the para-aramid fibrid film-like particles of claim 1 .
14. A paper made of constituents comprising at least 10 wt. % of the para-aramid fibrid film-like particles of claim 1 .
15. The method according to claim 8 wherein the dope is converted to para-aramid fibrid film-like particles by:
spinning the dope through a jet spin nozzle to obtain an aramid stream, hitting the aramid stream with a coagulant at an angle wherein the vector of the coagulant velocity perpendicular to the aramid stream is at least 10 m/s to coagulate the stream to para-aramid fibrid film-like particles, or
coagulating the dope by means of a rotor stator apparatus in which the aramid solution is applied through the stator on the rotor so that precipitating para-aramid fibrid film-like particles are subjected to shear forces while they are in a plastic deformable stage.
16. The para-aramid fibrid film-like particle of claim 1 , wherein the particle has a Canadian freeness number of between 40 and 790.
17. The para-aramid fibrid film-like particle of claim 1 , wherein the only polymers used to produce the para-aramid fibrid film-like particle are para-aramid.
18. The para-aramid fibrid film-like particle of claim 1 , wherein the para-aramid fibrid film-like particle consists of a para-aramid obtained by polycondensation of a para-oriented aromatic diamine and a para-oriented aromatic dicarboxylic acid halide.
19. The para-aramid fibrid film-like particle of claim 1 , wherein the
polymerizing of the para-oriented aromatic diamine and the para-oriented aromatic dicarboxylic acid halide to an aramid having at least 95% para-oriented bonds is in a mixture of solvents consisting of N-methylpyrrolidone or dimethylacetamide and calcium chloride or lithium chloride.