Patent US3926645A successfully refreshed from Google Patents.
US3926645A
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Sympathetic ink
Assignee: Individual
•
Filing: 1974-01-25
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Granted: 1975-12-16
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Expires: 1994-01-25
Abstract
Abstract An improved sympathetic ink is composed of a substantially water insoluble cellulose ether such as ethyl cellulose and methylene chloride or a solvent containing methylene chloride, preferably a mixture of methylene chloride and trichloro ethylene.
Inventors
- 👤 Walter Strahl
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 12:02
CPC Classifications
C; C09; C09D; C09D11/00; C09D11/50; C09D11/02; C09D11/14
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
76 words
A SYMPATHETIC INK WHICH IS INVISIBLE WHEN APPLIED TO PAPER OR OTHER MATERIALS HAVING AN ABSORBENT SURFACE AND WHICH BECOMES VISIBLE ON WETTING SAID PAPER OR OTHER MATERIAL, SAID INK CONSISTING OF A HALOGENATED HYDROCARBON SOLVENT CONSISTING ESSENTIALLY OF METHYLENE CHLORIDE HAVING DISSOLVED THEREIN BETWEEN ABOUT 0.25% AND ABOUT 1% OF A SUBSTANTIALLY COLORLESS, SUBSTANTIALLY WATER INSOLUBLE CELLULOSE ETHER OF A DEGREE OF SUBSTITUTION OF AT LEAST 2.42 AND AN ETHOXYL CONTENT OF AT LEAST 47.5%.
Claim 2
Dependent Claim
76 words
A SYMPATHETIC INK WHICH IS INVISIBLE WHEN APPLIED TO PAPER OR OTHER MATERIALS HAVING AN ABSORBENT SURFACE AND WHICH BECOMES VISIBLE ON WETTING SAID PAPER OR OTHER MATERIAL, SAID INK CONSISTING OF A HALOGENATED HYDROCARBON SOLVENT CONSISTING ESSENTIALLY OF METHYLENE CHLORIDE HAVING DISSOLVED THEREIN BETWEEN ABOUT 0.25% AND ABOUT 1% OF A SUBSTANTIALLY COLORLESS, SUBSTANTIALLY WATER INSOLUBLE CELLULOSE ETHER OF A DEGREE OF SUBSTITUTION OF AT LEAST 2.42 AND AN ETHOXYL CONTENT OF AT LEAST 47.5%.
Claim 3
Dependent Claim
39 words
The sympathetic ink of claim 1, in which the water insoluble cellulose ether is ethyl cellulose of a degree of substitution between at least 2.42 to about 2.53 and an ethoxyl content between at least 47.5% to about 49.5%.
Claim 4
Dependent Claim
13 words
The sympathetic ink of claim 1, in which the solvent is methylene chloride.
Claim 5
Dependent Claim
19 words
The sympathetic ink of claim 1, in which the solvent is a mixture of methylene chloride and trichloro ethylene.
Claim 6
Dependent Claim
26 words
The sympathetic ink of claim 1, in which the solvent is a mixture of methylene chloride and a halogenated alkane with 1 to 2 carbon atoms.
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 |