Patent US5234652A successfully refreshed from Google Patents.
US5234652A
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US
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Process for the continuous production of high modulus articles from high molecular weight plastics
Assignee: Individual
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Filing: 1991-10-21
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Granted: 1993-08-10
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Expires: 2011-10-21
Abstract
Abstract A process for producing a high modulus article includes forcing a high molecular weight plastic material, such as polyethylene, through a passage of which the cross-sectional area diminishes in the forward direction of plastic flow, thus producing an extrudate. The plastic material is extruded while it is close to or at its melt temperature, and it is lubricated to obtain substantially plug flow through the passage. The speed at which the plastic material flows through the passage is adjusted so that the elongational velocity gradient at any longitudinal position within the passage does not exceed about 2.6 sec.-1, thus minimizing the degree of molecular orientation in the extrudate. The extrudate can be deformed by drawing while it is maintained at or close to its melt temperature, thus producing an oriented, deformed extrudate. The oriented extrudate is then quickly cooled to preserve the orientation. A suitable plastic material is high molecular weight polyethylene with an average molecular weight lying between about 500,000 and about 1,500,000.
Inventors
- 👤 Raymond T. Woodhams
- 👤 Kenneth R. Tate
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 13:11
CPC Classifications
B; B29; B29C; B29C55/00; B29C55/02; B29C55/04; B29C55/06; B29C48/00; B29C48/022; B29C48/03; B29C48/06; B29C48/25; B29C48/355; B29C48/78; B29C48/793; B29C48/797; B29C48/80; B29C48/83; B29C48/832; B29C48/86; B29C48/88; B29C48/91; B29C48/94; B29C48/95; B29C55/005; B29C48/09; B29K; B29K2023/00; B29K2023/04; B29K2023/06; B29K2023/0658; B29K2023/0675; B29K2023/0683
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
185 words
A process for the continuous production of a high modulus article, including the steps: a) continuously forcing a high molecular weight plastic material, while it is close to or at its melt temperature, through a passage of which the cross-sectional area diminishes in the forward direction of plastic flow, thereby to produce an extrudate, said plastic material being substantially free of diluents and solvents; b) lubricating the plastic material adjacent the passage to obtain substantially plug flow of the material through said passage; c) adjusting the speed of plastic flow with respect to the shape of the passage so that the Elongational Velocity Gradient (EVG) at any longitudinal position within the passage does not exceed a critical EVG defined as that value below which the extrudate contains substantially no fibrillar molecular orientation, thereby resulting in an extrudate with substantially no fibrillar molecular orientation as characterized by a morphological transition at substantially 152° C.; d) deforming the extrudate, while it is maintained at or close to its melt temperature, to produce an oriented, deformed extrudate; and e) quickly cooling the deformed extrudate to preserve the orientation.
Claim 2
Dependent Claim
185 words
A process for the continuous production of a high modulus article, including the steps: a) continuously forcing a high molecular weight plastic material, while it is close to or at its melt temperature, through a passage of which the cross-sectional area diminishes in the forward direction of plastic flow, thereby to produce an extrudate, said plastic material being substantially free of diluents and solvents; b) lubricating the plastic material adjacent the passage to obtain substantially plug flow of the material through said passage; c) adjusting the speed of plastic flow with respect to the shape of the passage so that the Elongational Velocity Gradient (EVG) at any longitudinal position within the passage does not exceed a critical EVG defined as that value below which the extrudate contains substantially no fibrillar molecular orientation, thereby resulting in an extrudate with substantially no fibrillar molecular orientation as characterized by a morphological transition at substantially 152° C.; d) deforming the extrudate, while it is maintained at or close to its melt temperature, to produce an oriented, deformed extrudate; and e) quickly cooling the deformed extrudate to preserve the orientation.
Claim 3
Dependent Claim
30 words
The process claimed in claim 1, in which said passage communicates at its downstream end with a die land having a length/diameter ratio lying between about 10 and about 35.
Claim 4
Dependent Claim
36 words
The process claimed in claim 1 or claim 2, in which the extrudate undergoes an annealing step prior to being deformed, the annealing taking place at a temperature close to the melt temperature of the material.
Claim 5
Dependent Claim
28 words
The process claimed in claim 1 or claim 2, in which the EVG at any longitudinal position within the passage does not exceed about 2.6 sec -1 .
Claim 6
Dependent Claim
37 words
The process claimed in claim 1, in which the plastic material is polyethylene with an average molecular weight lying between about 500,000 and about 1,500,000, and in which the critical EVG is substantially 1.6 sec -1 .
Claim 7
Dependent Claim
28 words
The process claimed in claim 1 or claim 2, in which the plastic material is polyethylene with an average molecular weight lying between about 750,000 and about 1,000,000.
Claim 8
Dependent Claim
39 words
The process claimed in claim 1 or claim 2, in which the passage is provided in a die, and consists of a series of conical portions of which the cone angle decreases in the forward direction of plastic flow.
Claim 9
Dependent Claim
24 words
The process claimed in claim 1 or claim 2, in which the extrudate is deformed by being drawn in the direction of its elongation.
Claim 10
Dependent Claim
30 words
The process claimed in claim 5, in which said passage communicates at its downstream end with a die land having a length/diameter ratio lying between about 10 and about 35.
Claim 11
Dependent Claim
33 words
The process claimed in claim 5, in which the extrudate undergoes an annealing step prior to being deformed, the annealing taking place at a temperature close to the melt temperature of the material.
Claim 12
Dependent Claim
28 words
The process claimed in claim 5 or claim 10, in which the EVG at any longitudinal position within the passage does not exceed about 1.3 sec -1 .
Claim 13
Dependent Claim
25 words
The process claimed in claim 5, in which the plastic material is polyethylene with an average molecular weight lying between about 750,000 and about 1,000,000.
Claim 14
Dependent Claim
36 words
The process claimed in claim 12, in which the passage is provided in a die, and consists of a series of conical portions of which the cone angle decreases in the forward direction of plastic flow.
Claim 15
Dependent Claim
21 words
The process claimed in claim 13, in which the extrudate is deformed by being drawn in the direction of its elongation.
Claim 16
Dependent Claim
145 words
A process comprising the steps: a) continuously forcing a high molecular weight plastic material, while it is close to or at its melt temperature, through a passage of which the cross-sectional area diminishes in the forward direction of plastic flow, thereby to produce an extrudate, said plastic material being substantially free of diluents and solvents; b) lubricating the plastic material adjacent the passage to obtain substantially plug flow of the material through said passage; and c) adjusting the speed of plastic flow with respect to the shape of the passage so that the Elongational Velocity Gradient (EVG) at any longitudinal position within the passage does not exceed a critical EVG defined as that value below which the extrudate contains substantially no fibrillar molecular orientation, thereby resulting in an extrudate with substantially no fibrillar molecular orientation as characterized by a morphological transition at substantially 152° C.
Claim 17
Dependent Claim
145 words
A process comprising the steps: a) continuously forcing a high molecular weight plastic material, while it is close to or at its melt temperature, through a passage of which the cross-sectional area diminishes in the forward direction of plastic flow, thereby to produce an extrudate, said plastic material being substantially free of diluents and solvents; b) lubricating the plastic material adjacent the passage to obtain substantially plug flow of the material through said passage; and c) adjusting the speed of plastic flow with respect to the shape of the passage so that the Elongational Velocity Gradient (EVG) at any longitudinal position within the passage does not exceed a critical EVG defined as that value below which the extrudate contains substantially no fibrillar molecular orientation, thereby resulting in an extrudate with substantially no fibrillar molecular orientation as characterized by a morphological transition at substantially 152° C.
Claim 18
Dependent Claim
25 words
The process claimed in claim 15, in which the EVG at any longitudinal position within the passage does not exceed about 1.3 sec -1 .
Claim 19
Dependent Claim
37 words
The process claimed in claim 16, in which the plastic material is polyethylene with an average molecular weight lying between about 500,000 and about 1,500,000, and in which the critical EVG is about 2.6 sec -1 .
Claim 20
Dependent Claim
25 words
The process claimed in claim 17, in which the plastic material is polyethylene with an average molecular weight lying between about 750,000 and about 1,000,000.
Claim 21
Dependent Claim
40 words
The process claimed in claim 15 or claim 18, in which the passage is provided in a die, and consists of a series of concatenated conical portions of which the cone angle decreases in the forward direction of plastic flow.
Claim 22
Dependent Claim
38 words
The process claimed in claim 1, in which the plastic material is polyethylene with an average molecular weight lying between about 5,000,000 and about 6,000,000, and in which the critical EVG is less than 0.4 sec -1 .
Claim 23
Dependent Claim
38 words
The process claimed in claim 15, in which the plastic material is polyethylene with an average molecular weight lying between about 5,000,000 and about 6,000,000, and in which the critical EVG is less than 0.4 sec -1 .
Claim 24
Dependent Claim
33 words
The process claimed in claim 1, in which the continuous forcing of the plastic material through said passage is carried out by utilizing a screw extruder having a barrel with internal longitudinal grooves.
Claim 25
Dependent Claim
33 words
The process claimed in claim 15, in which the continuous forcing of the plastic material through said passage is carried out by utilizing a screw extruder having a barrel with internal longitudinal grooves.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-08-09 | 1997-02-08 | 1997-08-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-08-09 | 2001-02-08 | 2001-08-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-08-09 | 2005-02-08 | 2005-08-10 | $7700.00 | Window Closed / Lapsed |