US3927156A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Production of ink-feeding and writing core for writing instrument
Assignee: Kureha Corp
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Filing: 1973-02-15
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Granted: 1975-12-16
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Expires: 1993-02-15
Abstract
Abstract Method for producing a writing core having a porosity in the range of from 30 to 60%, which core is made from polyvinylidene fluoride powder having a bulk density of 0.5 to 1.0 g/ml and a uniform particle size range of 10 to 300 microns, produced by filling a mold with the powder, heating the powder to a temperature of from the melting point thereof to 350*C in a pressure-free state and heat-treating the formed core taken out of the mold at a temperature of from 70*C to a temperature lower than the melting point thereof for more than 3 hours.
Inventors
- 👤 Shinsuke Yoshikawa
- 👤 Hiroyuki Endo
- 👤 Shuji Terasaki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 14:04
CPC Classifications
B; B43; B43K; B43K1/00; B43K1/006
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
158 words
A METHOD FOR PRODUCING A POROUS INK-FEEDING WRITING INSTRUMENT CORE FROM POLYVINYLIDENE FLUORIDE SPHERICAL PARTICLES HAVING AN INHERENT VISCOSITY OF 1.0 TO 4.0 WHEN MEASURED IN 0.4G/100 CC SOLUTION OF N,N''-DIMETHYLFORMAMIDE, A BULK DENSITY OF 0.5-1.0G/ML AND A SIZE RANGE OF 10-300 MICRONS, COMPRISING: A. PLACING SAID PARTICLES IN A METAL MOLD HAVING THE SHAPE OF A PEN CORE; B. HEATING SAID PARTICLES IN A PRESSURE FREE STATE TO A TEMPERATURE BETWEEN THE MELTING POINT AND 350*C, WHEREIN SAID PARTICLES, DUE TO THEIR INHERENT VISCOSITY, RETAIN THEIR GENERAL SHAPE WITH INTERSTICES THEREBETWEEN; C. COOLING SAID MOLTEN PARTICLES TO SOLIDIFY SAME INTO THE SHAPE OF SAID PEN CORE; D. REMOVING SAID PEN CORE FROM SAID MOLD: E. PLACING THE PEN CORE IN A FURNACE; F. HEATING SAID PEN CORE IN THE FURNACE AT A TEMPERATURE BETWEEN THE MELTING POINT AND 70*C FOR MORE THAN 3 HOURS; AND G. COOLING SAID PEN CORE TO PRODUCE THEREIN A POROSITY OF 30-50%.
Claim 2
Independent Claim
158 words
A METHOD FOR PRODUCING A POROUS INK-FEEDING WRITING INSTRUMENT CORE FROM POLYVINYLIDENE FLUORIDE SPHERICAL PARTICLES HAVING AN INHERENT VISCOSITY OF 1.0 TO 4.0 WHEN MEASURED IN 0.4G/100 CC SOLUTION OF N,N''-DIMETHYLFORMAMIDE, A BULK DENSITY OF 0.5-1.0G/ML AND A SIZE RANGE OF 10-300 MICRONS, COMPRISING: A. PLACING SAID PARTICLES IN A METAL MOLD HAVING THE SHAPE OF A PEN CORE; B. HEATING SAID PARTICLES IN A PRESSURE FREE STATE TO A TEMPERATURE BETWEEN THE MELTING POINT AND 350*C, WHEREIN SAID PARTICLES, DUE TO THEIR INHERENT VISCOSITY, RETAIN THEIR GENERAL SHAPE WITH INTERSTICES THEREBETWEEN; C. COOLING SAID MOLTEN PARTICLES TO SOLIDIFY SAME INTO THE SHAPE OF SAID PEN CORE; D. REMOVING SAID PEN CORE FROM SAID MOLD: E. PLACING THE PEN CORE IN A FURNACE; F. HEATING SAID PEN CORE IN THE FURNACE AT A TEMPERATURE BETWEEN THE MELTING POINT AND 70*C FOR MORE THAN 3 HOURS; AND G. COOLING SAID PEN CORE TO PRODUCE THEREIN A POROSITY OF 30-50%.
Claim 3
Dependent Claim
55 words
The method according to claim 1, wherein the polyvinylidene fluoride particles are obtained by preheating a polyvinylidene fluoride powder having a bulk density of below 0.5 g/ml at a temperature range of 200*C to 300*C in a fluidized bed to heat-shrink the polyvinylidene fluoride powder, prior to the first heat treatment in the metal mold.
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) | 1978-12-15 | 1979-06-16 | 1979-12-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-15 | 1983-06-16 | 1983-12-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-15 | 1987-06-16 | 1987-12-16 | $7700.00 | Window Closed / Lapsed |