Process for the continuous preparation of homogeneous solutions of high-molecular polymers

Claim 2

Process for the continuous preparation of homogeneous solutions of high-molecular weight polymers which comprises forming a suspension of a finely divided high-molecular weight polymer in a suitable solvent or mixture of solvents, which solvent(s) is (are) liquid at room temperature, and processing said suspensin through a screw extruder operated at a rotational speed of from about 30 to about 300 revolutions/minute, and equipped with alternate mixing and conveying sections, during such a required residence time (t) in the extruder that (t) expressed in minutes is at most 0.3 D, wherein D denotes the diameter of said extruder expressed in millimetres, at a temperature above the dissolution temperature of said polymer in said solvent(s) and below the boiling point of the solvent(s) at the prevailing operating pressure, and employing a mixing and kneading treatment therein at a mechanical shear rate between about 30 and 200 sec.- l .

Claim 3

Process according to claim 1, wherein co-rotation twin-screw extruder is employed.

Claim 4

Process according to claim 1 or 2 wherein the required residence time (t) in said extruder is at most (0.2 x D) minutes.

Claim 5

Process according to claims 1-3 wherein said residence time is at most about 30 minutes.

Claim 6

Process according to claims 1-4 wherein the said polymer is a linear polyethylene having a weight-average molecular weight of at least 4 x 105.

Claim 7

Process according to claim 5 wherein said molecular weight is at least 8 x 105.

Claim 8

Process according to claims 1-6 wherein the temperature of the suspension and the solution in said extruder is maintained within the range of 140 ° to 220 °C.

Claim 9

Process according to claims 1-7 wherein said rotational speed is from about 150 to 300 rpm.

Claim 10

Process according to claims 1-8 wherein said suspension is transformed into a homogeneous solution containing at least 50 wt.% solvent.

Claim 11

Process according to claims 1-9 wherein the polymer content of said suspension is from 1 to 40 wt.%.

Claim 12

Process according to claims 1-10 wherein said mechanical shear rate is from 100 to 300 sec. -1 .

Claim 13

Process according to claims 1-11 wherein the finely divided polymer and the solvent(s) are introduced into the extruder in separate feed streams and the suspension and the solution are both formed within the extruder.

Claim 14

A process for the continuous forming of highly stretchable gel filaments, tapes, tubes and films from suspensions of high molecular weight polymers which comprises processing a 1-50 wt.% suspension of a finely divided polymer in a suitable solvent or mixture of solvents which solvent(s) is (are) liquid at room temperature, through a screw extruder operated at a rotational speed of from 30 to about 300 r.p.m. and equipped with alternate mixing and conveying sections, during such a required residence time (t) in said extruder that (t) expressed in minutes is at most 0.3 D, D denoting the diameter of said extruder in millimeters at a temperature above the dissolution point of said polymer in said solvent(s) and below the boiling point of the solvent(s) at the prevailing operating pressure, while employing a mixing and kneading treatment therein with a mechanical shear rate between about 30 and 2,000 sec.- 1 , and thereafter passing the thus- formed homogeneous solution out of the extruder through a spinning orifice, cooling the extrudate thus obtained to below the gel-point to obtain a homogeneous gel filament, tape, film or tube, according to the configuration of the said orifice.

Claim 15

A process for the continuous forming of highly stretchable gel filaments, tapes, tubes and films from suspensions of high molecular weight polymers which comprises processing a 1-50 wt.% suspension of a finely divided polymer in a suitable solvent or mixture of solvents which solvent(s) is (are) liquid at room temperature, through a screw extruder operated at a rotational speed of from 30 to about 300 r.p.m. and equipped with alternate mixing and conveying sections, during such a required residence time (t) in said extruder that (t) expressed in minutes is at most 0.3 D, D denoting the diameter of said extruder in millimeters at a temperature above the dissolution point of said polymer in said solvent(s) and below the boiling point of the solvent(s) at the prevailing operating pressure, while employing a mixing and kneading treatment therein with a mechanical shear rate between about 30 and 2,000 sec.- 1 , and thereafter passing the thus- formed homogeneous solution out of the extruder through a spinning orifice, cooling the extrudate thus obtained to below the gel-point to obtain a homogeneous gel filament, tape, film or tube, according to the configuration of the said orifice.

Claim 16

Process according to claim 13 wherein a gear pump is interposed between the exit of the extruder and the spinning orifice and said homogeneous solution is passed through said gear pump.

Claim 17

High strength and high modulus filaments, tapes, films or tubes obtained from a homogeneous solution of a high-molecular weight polymer prepared according to the process of claims 1-12.

Claim 18

High strength and high modulus filaments, tapes, films or tubes obtained by stretching a gel article obtained according to claims 13 or 14.