US5047121A
Expired / Lapsed
US
⏱️ 0.0 years remaining
High grade polyethylene paper
Assignee: EIDP Inc
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Filing: 1990-09-20
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Granted: 1991-09-10
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Expires: 2010-09-20
Abstract
Abstract A process is disclosed for producing high grade synthetic paper containing at least 97 wt. % polyethylene on conventional continuous wet-lay paper-making equipment. In particular, the process comprises preparing a pulp furnish of 97-99.5 wt. % oriented polyethylene fibers and 0.5-3.0 wt. % polyvinyl alcohol fibers and depositing the fibers on the forming screen of a conventional wet-lay paper machine. The resulting waterleaf sheet is then dried on heated PTFE-coated drying cans, using a particular drying profile to reduce sticking and elongation, and then thermally bonded to provide a polyethylene paper having high strength, low defects and excellent uniformity. A process for producing the pulp fibers used in the paper-making process is also disclosed.
Inventors
- 👤 Gurvinder P. S. Kochar
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 20:15
CPC Classifications
D; D21; D21H; D21H17/00; D21H13/00; D21H13/10; D21H13/12; D21H13/14; D21H13/16; D21H25/00; D21H25/04
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
174 words
A process for preparing a synthetic paper containing at least 97% polyethylene, on conventional continuous wet-lay, paper-making equipment, comprising the steps of: (a) preparing a pulp furnish comprising: (i) 97-99.5% polyethylene fibrids having an average length of between 0.7 to 1.0 mm, a defect level of between 0 to 6%, a birefrigence of at least 0.030 and a coarseness of between 0.15 to 0.222 mg/m; and (ii) 0.5-3.0% polyvinyl alcohol fibers; (b) depositing the furnish on the screen of a paper-making machine to form a waterleaf sheet; (c) drying the resulting waterleaf sheet on heated drying cans wherein the drying cans have a drying profile such that an initial drying phase is provided at a temperature of between 200° to 270° F. to melt the polyvinyl alcohol fibers and a second drying phase is provided at a temperature between 190° to 240° F. to control stretch and elongation of the fibers; and (d) thermally bonding the dried fibers at a temperature between 250°-315° F. to provide a Frazier porosity of at least 4 ft3/min./ft2.
Claim 2
Dependent Claim
174 words
A process for preparing a synthetic paper containing at least 97% polyethylene, on conventional continuous wet-lay, paper-making equipment, comprising the steps of: (a) preparing a pulp furnish comprising: (i) 97-99.5% polyethylene fibrids having an average length of between 0.7 to 1.0 mm, a defect level of between 0 to 6%, a birefrigence of at least 0.030 and a coarseness of between 0.15 to 0.222 mg/m; and (ii) 0.5-3.0% polyvinyl alcohol fibers; (b) depositing the furnish on the screen of a paper-making machine to form a waterleaf sheet; (c) drying the resulting waterleaf sheet on heated drying cans wherein the drying cans have a drying profile such that an initial drying phase is provided at a temperature of between 200° to 270° F. to melt the polyvinyl alcohol fibers and a second drying phase is provided at a temperature between 190° to 240° F. to control stretch and elongation of the fibers; and (d) thermally bonding the dried fibers at a temperature between 250°-315° F. to provide a Frazier porosity of at least 4 ft3/min./ft2.
Claim 3
Dependent Claim
16 words
The process according to claim 1 wherein the drying cans are coated with a release coating.
Claim 4
Dependent Claim
12 words
The process according to claim 1 wherein the release coating is polytetrafluoroethylene.
Claim 5
Dependent Claim
173 words
A process for preparing a synthetic paper containing at least 97% polyethylene, on conventional continuous wet-lay, paper-making equipment, comprising the steps of: (a) preparing a pulp furnish comprising: (i) 97.5-98.5% polyethylene fibrids having an average length of between 0.78 to 0.80 mm, a defect level of between 1 to 4%, a birefrigence of at least 0.030 and a coarseness of between 0.170 to 0.185 mg/m; and (ii) 1.5-2.5% polyvinyl alcohol fibers; (b) depositing the furnish on the screen of a paper-making machine to form a waterleaf sheet; (c) drying the resulting waterleaf on heated drying cans wherein the drying cans have a drying profile such that an initial drying phase is provided at a temperature of between 210° to 250° F. to melt the polyvinyl alcohol fibers and a second drying phase is provided at a temperature between 195° to 205° F. to control stretch and elongation of the fibers; and (d) thermally bonding the dried fibers at a temperature between 270°-305° F. to provide a Frazier porosity of at least 4 ft3/min./ft2.
Claim 6
Dependent Claim
173 words
A process for preparing a synthetic paper containing at least 97% polyethylene, on conventional continuous wet-lay, paper-making equipment, comprising the steps of: (a) preparing a pulp furnish comprising: (i) 97.5-98.5% polyethylene fibrids having an average length of between 0.78 to 0.80 mm, a defect level of between 1 to 4%, a birefrigence of at least 0.030 and a coarseness of between 0.170 to 0.185 mg/m; and (ii) 1.5-2.5% polyvinyl alcohol fibers; (b) depositing the furnish on the screen of a paper-making machine to form a waterleaf sheet; (c) drying the resulting waterleaf on heated drying cans wherein the drying cans have a drying profile such that an initial drying phase is provided at a temperature of between 210° to 250° F. to melt the polyvinyl alcohol fibers and a second drying phase is provided at a temperature between 195° to 205° F. to control stretch and elongation of the fibers; and (d) thermally bonding the dried fibers at a temperature between 270°-305° F. to provide a Frazier porosity of at least 4 ft3/min./ft2.
Claim 7
Dependent Claim
16 words
A process according to claim 4 wherein the drying cans are coated with a release coating.
Claim 8
Dependent Claim
12 words
A process according to claim 5 wherein the release coating is polytetrafluoroethylene.
Claim 9
Dependent Claim
11 words
A wet-laid filter paper prepared by the process of claim 1.
Claim 10
Dependent Claim
15 words
A wet-laid, dried and thermally bonded paper sheet prepared by the process of claim 1.
Claim 11
Dependent Claim
48 words
An improved fibrous pulp of oriented polyethylene fibrids having a birefrigence of at least 0.030, the fibrids averaging between 0.7 to 1.0 mm in length, the improvement comprising the fibrids having a coarseness of between 0.150 to 0.222 mg/m and a defect level of between 0 to 6%.
Claim 12
Dependent Claim
48 words
An improved fibrous pulp of oriented polyethylene fibrids having a birefrigence of at least 0.030, the fibrids averaging between 0.7 to 1.0 mm in length, the improvement comprising the fibrids having a coarseness of between 0.150 to 0.222 mg/m and a defect level of between 0 to 6%.
Claim 13
Dependent Claim
11 words
A wet-laid filter paper prepared from the pulp of claim 9.
Claim 14
Dependent Claim
15 words
A wet-laid, dried and thermally bonded paper sheet prepared from the pulp of claim 9.
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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) | 1994-09-09 | 1995-03-11 | 1995-09-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-09-09 | 1999-03-11 | 1999-09-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-09-09 | 2003-03-11 | 2003-09-10 | $7700.00 | Window Closed / Lapsed |