US3609377A
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Method for preparing alkali metal salts of cellulose sulfate and stabilized alkali metal salts of cellulose sulfate
Assignee: Kelco Co
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Filing: 1970-06-16
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Granted: 1971-09-28
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Expires: 1990-06-16
Abstract
Abstract Improved process for preparing alkali metal salts of cellulose sulfate, said process comprising adding at least about a stoichiometric quantity of a powdered alkali metal salt of a weak inorganic acid, e.g., a carbonate, bicarbonate, borate, phosphate or silicate, to a reaction mixture containing cellulose sulfate in admixture with a lower N-dialkyl amide, water formed from the sulfation reaction, and optionally a diluent other than a lower N-dialkyl amide. A controlled quantity of water is added to the reaction mixture in conjunction with the addition of the alkali metal salt of a weak inorganic acid and alternatively, part or all of the added water may be introduced as chemically bound water in the alkali metal salt. The amount of water is sufficient to promote contact between the reactants but insufficient to form a pasty reaction mass. The neutralization reaction is conducted with agitation until neutralization is essentially completed which is accompanied by a pH change from highly acid to about 7.0 or above. Method for preparing salts of cellulose sulfate having improved stability by coprecipitating said cellulose sulfate salts with an excess of an alkali metal salt of a weak inorganic acid in an effective amount to provide a stabilizing quantity of the salt of the weak inorganic acid in the precipitated product. Preferably, the excess of the salt of a weak inorganic acid is sufficient to provide at least about 0.1 percent by weight of the salt of the weak inorganic acid in the precipitated product. The coprecipitation may be carried out in the presence of divalent cations which enhance the coprecipitation and increase the percentage of the salt of the weak inorganic acid in the product. A cellulose sulfate salt having improved stability, said salt containing an excess of a salt of a weak inorganic acid in an effective quantity to stabilize the cellulose sulfate salt. Preferably, the salt of the weak inorganic acid is present in an amount of at least about 0.1 percent by weight.
Inventors
- 👤 David J Pettitt
- 👤 Jerome Edward Murray
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 09:55
CPC Classifications
C; C08; C08B; C08B5/00; C08B5/14
Claims Analysis
Total Claims: 33
Claim 1
Independent Claim
14 words
The process of claim 1 wherein said powdered alkali metal salt is sodium carbonate.
Claim 2
Dependent Claim
14 words
The process of claim 1 wherein said powdered alkali metal salt is sodium bicarbonate.
Claim 3
Dependent Claim
15 words
The process of claim 1 wherein said powdered alkali metal salt is a sodium phosphate.
Claim 4
Dependent Claim
15 words
The process of claim 1 wherein said powdered alkali metal salt is a sodium borate.
Claim 5
Dependent Claim
15 words
The process of claim 1 wherein said powdered alkali metal salt is a sodium silicate.
Claim 6
Dependent Claim
13 words
The process of claim 1 wherein said lower N-dialkyl amide is dimethyl formamide.
Claim 7
Dependent Claim
26 words
The process of claim 1 wherein the amount of added water ranges between about 12 to about 22 percent by weight of said sulfation reaction mixture.
Claim 8
Dependent Claim
37 words
The process of claim 1 wherein said alkali metal salt of a weak inorganic acid is employed in an amount sufficient to provide a stabilizing excess of said salt in said alkali metal salt of cellulose sulfate.
Claim 9
Dependent Claim
44 words
The process of claim 9 wherein said alkali metal salt of a weak inorganic acid is employed in an amount sufficient to provide an excess of at least about 0.1 percent by weight of said salt in said alkali metal salt of cellulose sulfate.
Claim 10
Dependent Claim
34 words
The process of claim 9 wherein said neutralization reaction is carried out in the presence of divalent cations selected from the group consisting of calcium, magnesium, copper, nickel or zinc cations, or mixtures thereof.
Claim 11
Dependent Claim
104 words
A process for preparing a stabilized water-soluble salt of cellulose sulfate having a degree of substitution ranging from 1 to 3, said procEss comprising admixing in aqueous media a cellulose sulfate or a water-soluble salt thereof, having a degree of substitution ranging from 1 to 3 with an alkali metal salt of a weak inorganic acid having an ionization constant ranging between about 10 4 and 10 13, and coprecipitating from said aqueous media a water-soluble salt of cellulose sulfate in admixture with said alkali metal salt of a weak inorganic acid in an amount sufficient to stabilize said coprecipitated salt of cellulose sulfate.
Claim 12
Dependent Claim
35 words
The process of claim 12 wherein said alkali metal salt of a weak inorganic acid is coprecipitated in an amount sufficient to constitute about 0.1 percent by weight of the precipitated salt of cellulose sulfate.
Claim 13
Dependent Claim
38 words
The process of claim 12 wherein said aqueous media contains from about 50 to about 500 parts per million of divalent cations selected from the group consisting of calcium, magnesium, copper, nickel, or zinc cations, or mixtures thereof.
Claim 14
Dependent Claim
52 words
The process of claim 12 wherein said cellulose sulfate or water-soluble salt thereof has a viscosity at a 1 percent concentration in aqueous media in excess of 20 cps., as measured with a Brookfield Synchro Electric Viscometer, Model LVF, at a spindle speed of 60 r.p.m. and a temperature of 25* C.
Claim 15
Dependent Claim
59 words
The process of claim 12 wherein said cellulose sulfate or water-soluble salt thereof has a viscosity at a 1 percent concentration in aqueous media of about 20 cps. or less ranging down to about 11 cps., as measured with a Brookfield Synchro Electric Viscometer, Model LVF, at a spindle speed of 60 r.p.m. and a temperature of 25* C.
Claim 16
Dependent Claim
30 words
The process of claim 14 wherein said aqueous media is ground water containing from about 50 to about 150 parts per million of calcium or magnesium ions or mixtures thereof.
Claim 17
Dependent Claim
29 words
The process of claim 12 wherein said alkali metal salt of a weak inorganic acid is a carbonate, a bicarbonate, a silicate, or a phosphate salt, or mixtures thereof.
Claim 18
Dependent Claim
20 words
The process of claim 12 wherein said cellulose sulfate has a degree of substitution ranging from about 2 to 3.
Claim 19
Dependent Claim
48 words
The process of claim 19 wherein said cellulose sulfate has a viscosity in a 1 percent concentration in aqueous media in excess of 100 cps. as measured with a Brookfield Synchro Electric Viscometer, Model LVF, at a spindle speed of 60 r.p.m. and a temperature of 25* C.
Claim 20
Dependent Claim
20 words
The process of claim 12 wherein a lower alcohol or acetone is added to said aqueous media to cause coprecipitation.
Claim 21
Dependent Claim
12 words
The process of claim 21 wherein said lower alcohol is isopropyl alcohol.
Claim 22
Dependent Claim
67 words
A composition of an alkali metal salt of cellulose sulfate having improved stability, said salt having a degree of substitution from about 1 to 3, said salt having uniformly incorporated therein an alkali metal salt of a weak inorganic acid in an effective amount to stabilize said cellulose sulfate salt, said weak inorganic acid having an ionization constant in water between about 10 4 and 10 13.
Claim 23
Dependent Claim
55 words
The composition of claim 23 wherein said alkali metal salt of cellulose sulfate has a viscosity in excess of 20 cps. at a concentration of 1 percent by weight in aqueous media as measured by a Brookfield Synchro Electric Viscometer, Model LVF, at a spindle speed of 60 r.p.m. and a temperature of 25* C.
Claim 24
Dependent Claim
62 words
The composition of claim 23 wherein said alkali metal salt of cellulose sulfate has a viscosity of about 20 cps. or less ranging down to about 11 cps. at a concentration of 1 percent by weight in aqueous media as measured by a Brookfield Synchro Electric Viscometer, Model LVF, at a spindle speed of 60 r.p.m. and a temperature of 25* C.
Claim 25
Dependent Claim
52 words
The composition of claim 24 wherein said cellulose sulfate salt has a viscosity in exCess of 100 cps. at a concentration of 1 percent by weight in aqueous media, as measured by a Brookfield Synchro Electric Viscometer, Model LVF, at a spindle speed of 60 r.p.m. and a temperature of 25* C.
Claim 26
Dependent Claim
23 words
The composition of claim 24 wherein said alkali metal salt of cellulose sulfate has a degree of substitution from about 2 to 3.
Claim 27
Dependent Claim
23 words
The composition of claim 25 wherein said alkali metal salt of cellulose sulfate has a degree of substitution from about 2 to 3.
Claim 28
Dependent Claim
23 words
The composition of claim 26 wherein said alkali metal salt of cellulose sulfate has a degree of substitution from about 2 to 3.
Claim 29
Dependent Claim
23 words
The composition of claim 23 wherein said weak inorganic acid has an ionization constant in water between about 10 6 and 10 13.
Claim 30
Dependent Claim
35 words
The composition of claim 23 wherein said alkali metal salt of a weak inorganic acid is present in said cellulose sulfate salt in at least about 0.1 percent by weight of said cellulose sulfate salt.
Claim 31
Dependent Claim
31 words
The composition of claim 31 wherein said alkali metal salt of a weak inorganic acid is a carbonate, a bicarbonate, a phosphate, a borate, or a silicate salt, or mixtures thereof.
Claim 32
Dependent Claim
23 words
The composition of claim 23 containing divalent cations selected from the group consisting of calcium, magnesium, copper, nickel, or zinc, or mixtures thereof.
Claim 33
Dependent Claim
21 words
The composition of claim 32 containing divalent cations selected from the group consisting of calcium, magnesium, copper, nickel, or mixtures thereof.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-09-27 | 1975-03-29 | 1975-09-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-09-27 | 1979-03-29 | 1979-09-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-09-27 | 1983-03-29 | 1983-09-28 | $7700.00 | Window Closed / Lapsed |