US5043121A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for removing polyacetal binder from molded ceramic greenbodies with acid gases
Assignee: Hoechst Celanese Chemical Co
•
Filing: 1990-05-03
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Granted: 1991-08-27
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Expires: 2010-05-03
Abstract
Abstract A process for rapidly removing the binder from a greenbody composed of a sinterable powder dispersed within a polyacetal binder is achieved by contacting the molded ceramic greenbody with an acid which depolymerizes the polyacetal binder.
Inventors
- 👤 Gerd Wingefeld
- 👤 Walter Hassinger
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 22:13
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/622; C04B35/626; C04B35/63; C04B35/632; C04B35/634; C04B35/63404; C04B35/6342; C04B35/63448; C04B35/63488; C04B35/638
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
61 words
A process for removing a binder material from a molded ceramic greenbody which has been formed by molding a ceramic composition containing a sinterable powder dispersed within a polyacetal binder, comprising contacting said molded ceramic greenbody with an acid which reacts with said polyacetal binder so as to depolymerize said polyacetal and cause the depolymerized products to pass from said greenbody.
Claim 2
Dependent Claim
61 words
A process for removing a binder material from a molded ceramic greenbody which has been formed by molding a ceramic composition containing a sinterable powder dispersed within a polyacetal binder, comprising contacting said molded ceramic greenbody with an acid which reacts with said polyacetal binder so as to depolymerize said polyacetal and cause the depolymerized products to pass from said greenbody.
Claim 3
Dependent Claim
20 words
The process of claim 1 wherein said acid is contacted with said greenbody in the form of an acid gas.
Claim 4
Dependent Claim
19 words
The process of claim 1 wherein said acid is selected from the group consisting sulfuric, nitric and hydrochloric acids.
Claim 5
Dependent Claim
24 words
The process of claim 2 wherein said acid gas is contacted with said ceramic greenbody at a temperature of from 70° to 200° C.
Claim 6
Dependent Claim
24 words
The process of claim 4 wherein said acid gas is contacted with said ceramic greenbody at a temperature of from 80° to 120° C.
Claim 7
Dependent Claim
12 words
The process of claim 1 wherein said polyacetal binder comprises oxymethylene units.
Claim 8
Dependent Claim
16 words
The process of claim 6 wherein said polyacetal contains at least 50 mol % oxymethylene units.
Claim 9
Dependent Claim
27 words
The process of claim 6 wherein said polyacetal is a copolymer containing oxymethylene units and oxyalkylene units wherein said alkylene group contains at least 2 carbon atoms.
Claim 10
Dependent Claim
25 words
The process of claim 8 wherein said polyacetal binder comprises a copolymer containing at least 50 mol % oxymethylene units and the remainder oxyethylene units.
Claim 11
Dependent Claim
31 words
The process of claim 1 wherein said sinterable powder is selected from the group consisting of aluminum oxide, zirconium oxide, silicon dioxide, silicon nitride, silicon carbide, silicon, ferrite and mixtures thereof.
Claim 12
Dependent Claim
11 words
The process of claim 10 wherein said sinterable powder is silicon.
Claim 13
Dependent Claim
21 words
The process of claim 1 wherein said polyacetal binder comprises from about 10 to 50 wt. % of said ceramic composition.
Claim 14
Dependent Claim
57 words
A process for producing ceramic articles comprising mixing a sinterable powder and a polyacetal binder to form a moldable ceramic composition, extrusion or injection molding said ceramic composition to form a ceramic greenbody and removing said binder from the greenbody by contacting the greenbody with an acid which reacts with said polyacetal binder to depolymerize said binder.
Claim 15
Dependent Claim
57 words
A process for producing ceramic articles comprising mixing a sinterable powder and a polyacetal binder to form a moldable ceramic composition, extrusion or injection molding said ceramic composition to form a ceramic greenbody and removing said binder from the greenbody by contacting the greenbody with an acid which reacts with said polyacetal binder to depolymerize said binder.
Claim 16
Dependent Claim
21 words
The process of claim 13 wherein said sinterable powder comprises from about 50 to about 87 volume % of said mixture.
Claim 17
Dependent Claim
14 words
The process of claim 13 wherein said acid is comprised of an acid gas.
Claim 18
Dependent Claim
19 words
The process of claim 13 wherein said acid is selected from the group consisting sulfuric, nitric and hydrochloric acids.
Claim 19
Dependent Claim
24 words
The process of claim 15 wherein said acid gas is contacted with said ceramic greenbody at a temperature of from 70° to 200° C.
Claim 20
Dependent Claim
24 words
The process of claim 17 wherein said acid gas is contacted with said ceramic greenbody at a temperature of from 80° to 120° C.
Claim 21
Dependent Claim
16 words
The process of claim 13 wherein said polyacetal contains at least 50 mol % oxymethylene units.
Claim 22
Dependent Claim
31 words
The process of claim 13 wherein said sinterable powder is selected from the group consisting of aluminum oxide, zirconium oxide, silicon dioxide, silicon nitride, silicon carbide, silicon, ferrite and mixtures thereof.
Claim 23
Dependent Claim
11 words
The process of claim 13 wherein said sinterable powder is silicon.
Claim 24
Dependent Claim
19 words
The process of claim 15 wherein said acid gas is contacted with said greenbody in an inert carrier gas.
Claim 25
Dependent Claim
21 words
The process of claim 13 wherein said polyacetal binder comprises from about 10 to 50 wt. % of said ceramic composition.
Claim 26
Dependent Claim
21 words
The process of claim 1 wherein said sinterable powder comprises from about 50 to about 87 volume % of said mixture.
Claim 27
Dependent Claim
80 words
A process for producing ceramic articles comprising mixing a sinterable powder and a polyacetal binder to form a moldable ceramic composition containing from about 50 to about 87 vol. % of said sinterable powder, extrusion or injection molding said ceramic composition to form a ceramic greenbody and removing said binder from the greenbody by contacting the greenbody with an acid gas at a temperature of from 70° to 200° C. to react with said polyacetal binder to depolymerize said binder.
Claim 28
Dependent Claim
80 words
A process for producing ceramic articles comprising mixing a sinterable powder and a polyacetal binder to form a moldable ceramic composition containing from about 50 to about 87 vol. % of said sinterable powder, extrusion or injection molding said ceramic composition to form a ceramic greenbody and removing said binder from the greenbody by contacting the greenbody with an acid gas at a temperature of from 70° to 200° C. to react with said polyacetal binder to depolymerize said binder.
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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) | 1994-08-26 | 1995-02-25 | 1995-08-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-08-26 | 1999-02-25 | 1999-08-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-08-26 | 2003-02-25 | 2003-08-27 | $7700.00 | Window Closed / Lapsed |