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US4516589A
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US
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Non-combustible carbonized cigarette filters
Assignee: Philip Morris USA Inc
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Filing: 1982-05-18
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Granted: 1985-05-14
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Expires: 2002-05-18
Abstract
Abstract Non-combustible carbonized cigarette filters are manufactured wherein porous cellulosic material is contacted with a film-forming aqueous solution of an inorganic salt selected from the group consisting of alkali metal and ammonium silicates, carbonates, hydrophosphites, diphosphites, phosphites, hypophosphates, orthophosphates, diphosphates, triphosphates, polymetaphosphates, peroxymonophosphates, peroxydiphosphates, orthoborates, metaborates, tetraborates and mixtures thereof so that the cellulosic material contains at least about 1%, preferably from about 2% to about 6%, of the salt on a dry weight basis and then pyrolyzing the treated cellulosic material in an inert atmosphere at a temperature of at least about 700 DEG C. to about 900 DEG C., under conditions such that at least about 15%, preferably from about 20% to about 40% of the initial weight of the cellulosic material remains after pyrolysis.
Inventors
- 👤 Norman B. Rainer
- 👤 Charles S. McClung
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 08:35
CPC Classifications
A; A24; A24D; A24D3/00; A24D3/06; A24D3/16; A24D3/08; A24D3/10
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
137 words
A non-combustible filter for a smoking article, comprising up to about a 40 mm length of a carbonized material prepared by: (a) contacting a sheet of porous cellulosic web material with a film-forming aqueous solution of an inorganic salt selected from the group consisting of alkali metal and ammonium silicates, carbonates, hydrophosphites, diphosphites, phosphites, hypophosphites, orthophosphates, diphosphates, triposphates, polymetaphosphates, peroxymonophosphates, peroxydiphosphates, orthoborates, metaborates, tetraborates and mixtures thereof so that the web material contains at least about 1% of the salt on a dry weight basis; then (b) laterally gathering and compressing the cellulosic material into a substantially cylindrical coherent bundle; and then (c) pyrolyzing the cellulosic material in an inert atmosphere at a temperature of at least about 700° C. such that at least about 15% of the initial weight of the cellulosic material remains after pyrolysis.
Claim 2
Dependent Claim
137 words
A non-combustible filter for a smoking article, comprising up to about a 40 mm length of a carbonized material prepared by: (a) contacting a sheet of porous cellulosic web material with a film-forming aqueous solution of an inorganic salt selected from the group consisting of alkali metal and ammonium silicates, carbonates, hydrophosphites, diphosphites, phosphites, hypophosphites, orthophosphates, diphosphates, triposphates, polymetaphosphates, peroxymonophosphates, peroxydiphosphates, orthoborates, metaborates, tetraborates and mixtures thereof so that the web material contains at least about 1% of the salt on a dry weight basis; then (b) laterally gathering and compressing the cellulosic material into a substantially cylindrical coherent bundle; and then (c) pyrolyzing the cellulosic material in an inert atmosphere at a temperature of at least about 700° C. such that at least about 15% of the initial weight of the cellulosic material remains after pyrolysis.
Claim 3
Dependent Claim
15 words
A filtered smoking article comprising a tobacco column and the non-combustible filter of claim 1.
Claim 4
Dependent Claim
112 words
A substantially cylindrical non-combustible filter for a cigarette comprising laterally folded interbonded fibers of pyrolyzed porous cellulosic web material, having a substantially random distribution and containing from about 0.4 to about 1.2 percent by weight of elementally determined, water-insoluble boron and phosphorous, said filter having a carbon content of at least about 75% by weight, a diameter of from about 5 mm to about 15 mm, a length of from about 4 mm to about 40 mm, a flexural strength of at least about 40 grams, a void space of from about 60% to about 95% and a resistance-to-draw of less than about 1 inch of water per inch of filter length.
Claim 5
Dependent Claim
112 words
A substantially cylindrical non-combustible filter for a cigarette comprising laterally folded interbonded fibers of pyrolyzed porous cellulosic web material, having a substantially random distribution and containing from about 0.4 to about 1.2 percent by weight of elementally determined, water-insoluble boron and phosphorous, said filter having a carbon content of at least about 75% by weight, a diameter of from about 5 mm to about 15 mm, a length of from about 4 mm to about 40 mm, a flexural strength of at least about 40 grams, a void space of from about 60% to about 95% and a resistance-to-draw of less than about 1 inch of water per inch of filter length.
Claim 6
Dependent Claim
40 words
The non-combustible filter of claim 1 wherein in step (a) the cellulosic material is contacted with the solution such that the cellulosic material contains from about 2% to about 6% by weight of the salt on a dry weight basis.
Claim 7
Dependent Claim
26 words
The non-combustible filter of claim 4 wherein the salt comprises a mixture of sodium tetraborate, potassium tetraborate or ammonium tetraborate and diammonium phosphate or dipotassium phosphate.
Claim 8
Dependent Claim
26 words
The non-combustible filter of claim 5 wherein the solution comprises sodium tetraborate and diammonium phosphate in a weight ratio of from about 3:1 to about 1:3.
Claim 9
Dependent Claim
40 words
The non-combustible filter of claim 1 wherein in step (b) the web material is laterally gathered and compressed such that it has a density, on a dry weight basis, of from about 0.1 to about 0.4 gram/cc, exclusive of additives.
Claim 10
Dependent Claim
28 words
The non-combustible filter of claim 1 wherein the sheet of web material is longitudinally crimped before it is laterally gathered and compressed into the substantially cylindrical coherent bundle.
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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) | 1988-05-13 | 1988-11-12 | 1989-05-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-05-13 | 1992-11-12 | 1993-05-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-05-13 | 1996-11-12 | 1997-05-14 | $7700.00 | Window Closed / Lapsed |