US4187269A — Extrusion process for reducing melt fracture

Claim 1

Independent Claim 125 words

In a process for preparing extruded articles with substantially reduced melt fracture and improved surface smoothness by flowing a heat plastified stream of an extrudable synthetic resinous thermoplastic material through an extrusion orifice, the steps performed prior thereto of: (a) physically separating the stream into a central core stream and first and second boundary streams on each side of the core stream; (b) while maintaining physical separation of the core and boundary streams, selectively heating the boundary streams to a temperature substantially hotter than the material in the core stream; (c) thereafter, recombining the streams prior to expelling the material out the extrusion orifice, said boundary streams being applied as relatively thin hot layers generally uniformly onto the opposite surfaces, respectively, of the core stream.

Claim 2

Dependent Claim 125 words

In a process for preparing extruded articles with substantially reduced melt fracture and improved surface smoothness by flowing a heat plastified stream of an extrudable synthetic resinous thermoplastic material through an extrusion orifice, the steps performed prior thereto of: (a) physically separating the stream into a central core stream and first and second boundary streams on each side of the core stream; (b) while maintaining physical separation of the core and boundary streams, selectively heating the boundary streams to a temperature substantially hotter than the material in the core stream; (c) thereafter, recombining the streams prior to expelling the material out the extrusion orifice, said boundary streams being applied as relatively thin hot layers generally uniformly onto the opposite surfaces, respectively, of the core stream.

Claim 3

Dependent Claim 15 words

The method of claim 1 wherein said streams are recombined generally near the extrusion orifice.

Claim 4

Dependent Claim 122 words

An extrusion process for reducing melt fracture and improving surface smoothness characterized by the steps of: (a) providing a source of a generally homogeneous, extrudable synthetic resinous thermoplastic material; (b) routing a major portion of the source material along a first primary flow path ultimately terminating in an extrusion orifice; (c) routing a minor portion of the source material to an area removed from the primary flow path; (d) generally selectively heating the material while in residence in said area to a temperature substantially hotter than the material in the primary flow path; (e) thereafter layering the selectively heated material onto at least one surface of the resin following the primary flow path prior to expelling the material through an extrusion orifice.

Claim 5

Dependent Claim 122 words

An extrusion process for reducing melt fracture and improving surface smoothness characterized by the steps of: (a) providing a source of a generally homogeneous, extrudable synthetic resinous thermoplastic material; (b) routing a major portion of the source material along a first primary flow path ultimately terminating in an extrusion orifice; (c) routing a minor portion of the source material to an area removed from the primary flow path; (d) generally selectively heating the material while in residence in said area to a temperature substantially hotter than the material in the primary flow path; (e) thereafter layering the selectively heated material onto at least one surface of the resin following the primary flow path prior to expelling the material through an extrusion orifice.

Claim 6

Dependent Claim 75 words

The process of claim 3 wherein step (c) comprises routing a minor portion of the material to first and second areas, respectively, removed from the primary flow path, step (d) comprises generally selectively heating the material in each said area, and step (e) comprises layering the selected material from said areas generally uniformly onto opposite surfaces, respectively, of the resin following along the primary flow path prior to expelling the material through an extrusion orifice.

Claim 7

Dependent Claim 18 words

The process of claim 4 wherein step (c) is practiced at a location generally near the extrusion orifice.

Claim 8

Dependent Claim 119 words

An extrusion process for reducing melt fracture and improving surface smoothness comprising the steps of: (a) providing a source of a heat plastified extrudable synthetic resinous thermoplastic material; (b) advancing the material along a first flow path toward an extrusion orifice; (c) diverting a portion material from the first flow path to a second flow path and generally selectively heating the diverted material while in residence in the second flow path to a temperature substantially hotter than the material in the first flow path; thereafter; (d) applying the selectively heated material as a relatively thin layer to one surface of the resin flowing in the first flow path approximately just prior to passing the material through an extrusion orifice.

Claim 9

Dependent Claim 119 words

An extrusion process for reducing melt fracture and improving surface smoothness comprising the steps of: (a) providing a source of a heat plastified extrudable synthetic resinous thermoplastic material; (b) advancing the material along a first flow path toward an extrusion orifice; (c) diverting a portion material from the first flow path to a second flow path and generally selectively heating the diverted material while in residence in the second flow path to a temperature substantially hotter than the material in the first flow path; thereafter; (d) applying the selectively heated material as a relatively thin layer to one surface of the resin flowing in the first flow path approximately just prior to passing the material through an extrusion orifice.

Claim 10

Dependent Claim 16 words

The process of claim 6 wherein steps (b) through (d) are performed within an extrusion die.

Claim 11

Dependent Claim 46 words

The process of claim 7 wherein material is diverted to plural secondary flow paths, thereafter selectively heated, and applied as a thin coating to substantially the entire surface area of the resin in the first flow path prior to expelling the material through the extrusion orifice.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1983-02-04	1983-08-06	1984-02-05	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1987-02-04	1987-08-06	1988-02-05	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1991-02-04	1991-08-06	1992-02-05	$7700.00	Window Closed / Lapsed

Extrusion process for reducing melt fracture

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