Patent US4246390A successfully refreshed from Google Patents.
US4246390A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Molding powder of ultra-high molecular weight polyethylene and process for its preparation
Assignee: CNA Holdings LLC
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Filing: 1980-04-21
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Granted: 1981-01-20
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Expires: 2000-04-21
Abstract
Abstract Ultra-high molecular weight polyethylene powder is heated at a temperature between its crystalline melting point and about 275° C. for a short period of time ranging from about one minute to about thirty minutes to obtain a molding powder having properties which facilitate the subsequent step of compression molding. Compression molded pieces made from heat-treated powder have better transparency, gloss and low-temperature mechanical properties than those made from untreated powder.
Inventors
- 👤 Alton L. Seaver
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 14:19
CPC Classifications
C; C08; C08J; C08J3/00; C08J3/12; B; B29; B29C; B29C43/00; B29C43/003; B29C43/32; B29C43/52; B29C67/00; B29C67/24; B29K; B29K2023/00; B29K2023/04; B29K2023/06; B29K2023/0658; B29K2023/0683; B29K2995/00; B29K2995/0037; B29K2995/0088; C08J2323/00; C08J2323/02; C08J2323/04; C08J2323/06; Y; Y10; Y10T; Y10T428/00; Y10T428/26; Y10T428/269
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
131 words
A process of heat treating a powder of ultra-high molecular weight polyethylene having a molecular weight of above about 1×10 6 as determined from its intrinsic viscosity in decalin solution at 135° C. by the formula, MW=5.37×10 4 (intrinsic viscosity) 1 .49 and a substantial amount of fine structures comprising nodules of less than about 1 micron size, crevices and fibrous structures as viewed under scanning electron microscope at×5000 magnification, said heat treating being conducted at a temperature in the range from about the crystalline melting point of said polyethylene but at least about 140° C. to about 275° C. for an effective period of time to produce a polyethylene powder which is substantially free of fine structures and which has a substantially smooth surface appearance when observed by SEM at×5000.
Claim 2
Dependent Claim
131 words
A process of heat treating a powder of ultra-high molecular weight polyethylene having a molecular weight of above about 1×10 6 as determined from its intrinsic viscosity in decalin solution at 135° C. by the formula, MW=5.37×10 4 (intrinsic viscosity) 1 .49 and a substantial amount of fine structures comprising nodules of less than about 1 micron size, crevices and fibrous structures as viewed under scanning electron microscope at×5000 magnification, said heat treating being conducted at a temperature in the range from about the crystalline melting point of said polyethylene but at least about 140° C. to about 275° C. for an effective period of time to produce a polyethylene powder which is substantially free of fine structures and which has a substantially smooth surface appearance when observed by SEM at×5000.
Claim 3
Dependent Claim
28 words
The process of claim 1 wherein the polyethylene powder is heated for a period of time effective to substantially destroy any fine structures as observed by SEM at×5000.
Claim 4
Dependent Claim
17 words
A process according to claim 1, wherein the powder is heat-treated for at least about one minute.
Claim 5
Dependent Claim
28 words
A process according to claim 1, wherein the powder is heat-treated for a period of time at least about two minutes but not more than about thirty minutes.
Claim 6
Dependent Claim
56 words
A process according to claim 1, wherein an ultra-high molecular weight polyethylene powder having a molecular weight of about 5×10 6 and a crystalline melting point of about 140° C., and more than about 99% of which is smaller than about 60 mesh screen, is heat-treated at about 200°-250° C. for about 2 to 10 minutes.
Claim 7
Dependent Claim
56 words
A process according to claim 1, wherein an ultra-high molecular weight polyethylene powder having a molecular weight of about 7×10 6 and a crystalline melting point of about 140° C., and more than about 98% of which is smaller than about 60 mesh screen, is heat-treated at about 200°-250° C. for about 2 to 10 minutes.
Claim 8
Dependent Claim
49 words
A process of heat treating a molding powder of ultra-high molecular weight polyethylene having a molecular weight of between about 5×10 6 and 7×10 6 and having a crystalline melting point of about 140° C., said heat-treatment being conducted at about 200°-250° C. for about two to ten minutes.
Claim 9
Dependent Claim
49 words
A process of heat treating a molding powder of ultra-high molecular weight polyethylene having a molecular weight of between about 5×10 6 and 7×10 6 and having a crystalline melting point of about 140° C., said heat-treatment being conducted at about 200°-250° C. for about two to ten minutes.
Claim 10
Dependent Claim
48 words
The process of claim 7 wherein the polyethylene has a molecular weight of about 5×10 6 , wherein more than about 99% of said polyethylene is smaller than about 60 mesh screen and wherein the heat-treatment is conducted at about 250° C. for about two to five minutes.
Claim 11
Dependent Claim
15 words
The process of claim 8 wherein the heat treatment is conducted for about two minutes.
Claim 12
Dependent Claim
49 words
The process of claim 8 wherein the polyethylene has a molecular weight of about 7×10 6 , wherein more than about 99% of said polyethylene is smaller than about 60 mesh screen, and wherein the heat treatment is conducted at about 250° C. for about two to five minutes.
Claim 13
Dependent Claim
14 words
The process of claim 10 wherein heat treatment is conducted for about two minutes.
Claim 14
Dependent Claim
57 words
A molding powder of ultra-high molecular weight polyethylene having a molecular weight of above about 1×10 6 , a crystalline melting point of about 140° C., and a substantially smooth surface appearance free of fine structures comprising nodules of less than about 1 micron size, crevices and fibrous structures as viewed under scanning electron microscope at×5000 magnification.
Claim 15
Dependent Claim
57 words
A molding powder of ultra-high molecular weight polyethylene having a molecular weight of above about 1×10 6 , a crystalline melting point of about 140° C., and a substantially smooth surface appearance free of fine structures comprising nodules of less than about 1 micron size, crevices and fibrous structures as viewed under scanning electron microscope at×5000 magnification.
Claim 16
Dependent Claim
21 words
A molding powder of ultra-high molecular weight polyethylene of claim 12, wherein the molecular weight is 1×10 6 -12×10 6 .
Claim 17
Dependent Claim
15 words
A molding powder of claim 13 having a molecular weight of about 5×10 6 .
Claim 18
Dependent Claim
15 words
A molding powder of claim 14 having a molecular weight of about 7×10 6 .
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-01-20 | 1984-07-21 | 1985-01-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-01-20 | 1988-07-21 | 1989-01-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-01-20 | 1992-07-21 | 1993-01-20 | $7700.00 | Window Closed / Lapsed |