US3617588A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Dip-coating process for preparing cellulose ether capsule shells
Assignee: Dow Chemical Co
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Filing: 1969-06-16
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Granted: 1971-11-02
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Expires: 1989-06-16
Abstract
Abstract The dip-coating process for preparing cellulose ether film products is improved by (A) dipping a die mandrel with an electrically conductive outer surface into an aqueous thermal gelling solution containing at least 20 wt. percent of a filmforming hydroxyalkyl alkyl cellulose ether, (B) removing the coated die mandrel from the aqueous solution, (C) rapidly converting the coating into a nonflowing cellulose ether gel by induction heating, and thereafter (D) drying the gelled coating to form a stable film product. This process is particularly useful in making water-soluble, pharmaceutical capsule shells.
Inventors
- 👤 Cyril A J Langman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 04:22
CPC Classifications
A; A61; A61K; A61K9/00; A61K9/48; A61K9/4816; B; B29; B29C; B29C41/00; B29C41/02; B29C41/14; Y; Y10; Y10S; Y10S264/00; Y10S264/37; Y10S264/46
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
43 words
The process of claim 1 where the cellulose ether is a hydroxypropylmethyl cellulose having a hydroxypropyl M.S of about 0.15- 0.35, a methyl D.S. of about 1.8- 2.0, and a 2 percent aqueous solution viscosity of about 2-7 cps. at 20* C. PG,11
Claim 2
Dependent Claim
32 words
The process of claim 2 where the coating solution contains about 25- 35 wt. percent of the hydroxypropylmethyl cellulose and has a viscosity of about 1,000- 4,000 cps. at the dip-coating temperature.
Claim 3
Dependent Claim
14 words
The process of claim 1 where the die mandrel is made of stainless steel.
Claim 4
Dependent Claim
20 words
The process of claim 1 where the induction heater operates at a frequency of about 250- 400 kilocycles per second.
Claim 5
Dependent Claim
136 words
The process of claim 1 where pharmaceutical capsule shells are prepared by: (A) Dip coating a stainless steel die mandrel with a 25-35 wt. percent aqueous solution of a hydroxypropylmethyl cellulose characterized by a hydroxypropyl M.S. of about 0.15- 0.35, a methyl D.S. of about 1.8- 2.0, and a 2 percent aqueous solution viscosity of about 2-7 cps. at 20* C. (B) removing the coated die mandrel from the cellulose ether solution and immediately placing it in an induction heating zone; (C) rapidly converting the cellulose ether coating into a nonflowing gel by induction heating in a magnetic field generated by an induction heating oil operating at a frequency of about 200-5,000 kilocycles per second; (D) drying the gelled cellulose ether coating in a hot-air oven; and (E) stripping the capsule shell from the die mandrel.
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) | 1974-11-01 | 1975-05-03 | 1975-11-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-11-01 | 1979-05-03 | 1979-11-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-11-01 | 1983-05-03 | 1983-11-02 | $7700.00 | Window Closed / Lapsed |