US4760129A — Process for preparing highly viscous polyhexameth…

Claim 1

Independent Claim 189 words

A process for preparing highly viscous polyhexamethyleneadipamide, comprising the steps of: introducing a melt of a polyhexamethyleneadipamide polymer having a relative viscosity of from about 2.5-2.7, measured in a 1% strength solution in 96% strength sulfuric acid, into an extruder having a plurality of degassing zones; polycondensing the polymer in the extruder by treatment in a plurality of serially arranged zones of alternatingiy elevated and reduced pressure, said elevated pressure zones having a pressure above atmospheric pressure and said reduced pressure zones having a pressure below atmospheric pressure; supplying in the zones of elevated pressure steam which is superheated to the temperature of the melt in an amount of from about 0.05-0.7 kg/kg of polymer to the melt; drawing off in the zones of reduced pressure any input vapor phase and water of condensation; and raising the temperature of the melt at a uniform rate over the length of the extruder from about 260°-280° C. in the first zone to about 280°-310° C. in the last zone whereby a film-forming polymer having a relative viscosity greater than the relative viscosity of the polymer introduced into the extruder is produced.

Claim 2

Dependent Claim 189 words

A process for preparing highly viscous polyhexamethyleneadipamide, comprising the steps of: introducing a melt of a polyhexamethyleneadipamide polymer having a relative viscosity of from about 2.5-2.7, measured in a 1% strength solution in 96% strength sulfuric acid, into an extruder having a plurality of degassing zones; polycondensing the polymer in the extruder by treatment in a plurality of serially arranged zones of alternatingiy elevated and reduced pressure, said elevated pressure zones having a pressure above atmospheric pressure and said reduced pressure zones having a pressure below atmospheric pressure; supplying in the zones of elevated pressure steam which is superheated to the temperature of the melt in an amount of from about 0.05-0.7 kg/kg of polymer to the melt; drawing off in the zones of reduced pressure any input vapor phase and water of condensation; and raising the temperature of the melt at a uniform rate over the length of the extruder from about 260°-280° C. in the first zone to about 280°-310° C. in the last zone whereby a film-forming polymer having a relative viscosity greater than the relative viscosity of the polymer introduced into the extruder is produced.

Claim 3

Dependent Claim 30 words

A process as claimed in claim 1, wherein the treatment of the melt is carried out in at least two of said zones each of elevated and of reduced pressure.

Claim 4

Dependent Claim 36 words

A process as claimed in claim 1, wherein the amount of superheated steam which is supplied to every second zone of elevated pressure is from 50-100% of the amount of steam fed into the preceding zone.

Claim 5

Dependent Claim 38 words

A process as claimed in claim 1, further comprising the step of uniformly reducing the pressure in the zones of reduced pressure from about 500-30 mbar in the first zone to about 50-30 mbar in the last zone.

Claim 6

Dependent Claim 33 words

A process as claimed in claim 1, wherein the polyamide melt is polycondensed in the presence of a phosphorus-containing compound in an amount of from about 0.03-1% by weight, based on the polyamide.

Claim 7

Dependent Claim 25 words

A process as claimed in claim 5, wherein said phosphorus-containing compound is selected from the group consisting of orthophosphoric acid, sodium hypophosphite and phenylphosphinic acid.

Claim 8

Dependent Claim 35 words

A process as claimed in claim 4, wherein the temperature reduction profile and the pressure reduction profile are selected relative to one another so as to produce a polyamide having a predetermined degree of polydispersion.

Claim 9

Dependent Claim 27 words

A process as claimed in claim 1, wherein the treatment of the melt is carried out in three of said zones each of elevated and reduced pressure.

Claim 10

Dependent Claim 27 words

A process as claimed in claim 1, wherein the process is carried out in a twin-screw extruder having closely meshing screws which turn in the same direction.

Claim 11

Dependent Claim 25 words

A process according to claim 1 wherein the pressure in each reduced pressure zone is less than the pressure in the previous reduced pressure zone.

Claim 12

Dependent Claim 182 words

A process for preparing highly vicous polyhexamethyleneadipamide, comprisinq the steps of: introducing a melt of a polyhexamethyleneadipamide polymer having a relative viscosity of from about 2.5-2.7, measured in a 1% strength solution in 96% strength sulfuric acid, into an extruder having a plurality of degassing zones; polycondensing the polymer in the extruder by treatment in a plurality of serially arranged zones of alternatingly elevated and reduced pressure, said elevated pressure zones having a pressure above atmospheric pressure and said reduced pressure zones having a pressure below atmospheric pressure; supplying in the zones of elevated pressure steam which is superheated to the temperature of the melt in an amount of from about 0.05-0.7 kg/kg of polymer to the melt; drawing off in the zones of reduced pressure any input vapor phase and water of condensation; and raising the temperature of the melt at a uniform rate over the length of the extruder from about 260°-280° C. in the first zone to about 280°-310° C. in the last zone whereby a polymer having a relative viscosity of from about 3.7 to 7.5 is produced.

Claim 13

Dependent Claim 182 words

A process for preparing highly vicous polyhexamethyleneadipamide, comprisinq the steps of: introducing a melt of a polyhexamethyleneadipamide polymer having a relative viscosity of from about 2.5-2.7, measured in a 1% strength solution in 96% strength sulfuric acid, into an extruder having a plurality of degassing zones; polycondensing the polymer in the extruder by treatment in a plurality of serially arranged zones of alternatingly elevated and reduced pressure, said elevated pressure zones having a pressure above atmospheric pressure and said reduced pressure zones having a pressure below atmospheric pressure; supplying in the zones of elevated pressure steam which is superheated to the temperature of the melt in an amount of from about 0.05-0.7 kg/kg of polymer to the melt; drawing off in the zones of reduced pressure any input vapor phase and water of condensation; and raising the temperature of the melt at a uniform rate over the length of the extruder from about 260°-280° C. in the first zone to about 280°-310° C. in the last zone whereby a polymer having a relative viscosity of from about 3.7 to 7.5 is produced.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1991-07-26	1992-01-25	1992-07-26	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1995-07-26	1996-01-25	1996-07-26	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1999-07-26	2000-01-25	2000-07-26	$7700.00	Window Closed / Lapsed

Process for preparing highly viscous polyhexamethyleneadipamide

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