US4509987A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Calcium carbonate dispersions
Assignee: Ciba Specialty Chemicals Water Treatments Ltd
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Filing: 1982-11-17
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Granted: 1985-04-09
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Expires: 2002-11-17
Abstract
Abstract Concentrated (e.g. above 72% by weight) dispersions of calcium carbonate ground to a particle size such that at least 87% by weight of the particles are less than 2 μm in size have a tendency to gel on standing. In the invention this tendency is minimized or eliminated by using, as dispersing agent, a copolymer of from 5 to 75% by weight AMPS and 95 to 25% by weight acrylic acid, or a water soluble salt thereof, having a molecular weight in the range 1000 to 20,000.
Inventors
- 👤 David Farrar
- 👤 Malcolm Hawe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 14:09
CPC Classifications
D; D21; D21H; D21H19/00; D21H19/36; D21H19/38; D21H19/385; C; C01; C01F; C01F11/00; C01F11/18; C01F11/185; D21H21/00; D21H21/50; D21H21/52
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
89 words
A dispersion in water containing at least 72% by weight of the dispersion of inorganic particulate material comprising calcium carbonate in the form of ground particles of which at least 87% by weight are less than 2 μm in size and a dispersing agent comprising a copolymer of from 5 to 75% by weight AMPS and 95 to 25% by weight acrylic acid, or a water soluble salt thereof, having a molecular weight in the range 1,000 to 20,000, and the dispersion remains as a flowable dispersion upon standing.
Claim 2
Dependent Claim
89 words
A dispersion in water containing at least 72% by weight of the dispersion of inorganic particulate material comprising calcium carbonate in the form of ground particles of which at least 87% by weight are less than 2 μm in size and a dispersing agent comprising a copolymer of from 5 to 75% by weight AMPS and 95 to 25% by weight acrylic acid, or a water soluble salt thereof, having a molecular weight in the range 1,000 to 20,000, and the dispersion remains as a flowable dispersion upon standing.
Claim 3
Dependent Claim
29 words
A dispersion according to claim 1 containing at least 72% by weight inorganic particulate material of which at least 87% by weight is less than 2 μm in size.
Claim 4
Dependent Claim
47 words
A dispersion according to claim 1 in which the particulate material in the dispersion consists of at least 72%, by weight of the dispersion, of calcium carbonate in the form of ground particles of which at least 87% by weight are less than 2 μm in size.
Claim 5
Dependent Claim
90 words
A dispersion in water containing a dispersing agent and at least 72%, by weight of the dispersion, of calcium carbonate ground particles of which at least 87% by weight are less than 2 μm in size, and in which the dispersion contains, as a dispersing agent, a copolymer of from 5 to 75% by weight AMPS and 95 to 25% by weight acrylic acid, or a water soluble salt thereof, having a molecular weight in the range 1000 to 20,000 and the dispersion remains as a flowable dispersion upon standing.
Claim 6
Dependent Claim
90 words
A dispersion in water containing a dispersing agent and at least 72%, by weight of the dispersion, of calcium carbonate ground particles of which at least 87% by weight are less than 2 μm in size, and in which the dispersion contains, as a dispersing agent, a copolymer of from 5 to 75% by weight AMPS and 95 to 25% by weight acrylic acid, or a water soluble salt thereof, having a molecular weight in the range 1000 to 20,000 and the dispersion remains as a flowable dispersion upon standing.
Claim 7
Dependent Claim
20 words
A dispersion according to claim 4 in which the molecular weight of the said copolymer is from 2000 to 6000.
Claim 8
Dependent Claim
29 words
A dispersion according to claim 4 in which the said copolymer is of 15 to 40% AMPS and 85 to 60% acrylic acid, or a water soluble salt thereof.
Claim 9
Dependent Claim
19 words
A dispersion according to claim 4 in which the said copolymer is present as the sodium or ammonium salt.
Claim 10
Dependent Claim
18 words
A dispersion according to claim 4 having a calcium carbonate content of from 74 to 80% by weight.
Claim 11
Independent Claim
124 words
A method of making a dispersion that remains flowable upon standing comprising grinding calcium carbonate in water containing a dispersing agent and then filtering the ground dispersion to yield a dispersion containing at least 72% by weight, based on the weight of dispersion, of ground calcium carbonate particles of which at least 87% by weight are less than 2 μm in size and then storing the dispersion, and in which the stored dispersion includes, as a dispersing agent, a copolymer of from 5 to 75% by weight AMPS and 95 to 25% by weight acrylic acid, or a water soluble salt thereof, having a molecular weight in the range 1000 to 20,000, and the dispersion remains as a flowable dispersion during the said storage.
Claim 12
Independent Claim
124 words
A method of making a dispersion that remains flowable upon standing comprising grinding calcium carbonate in water containing a dispersing agent and then filtering the ground dispersion to yield a dispersion containing at least 72% by weight, based on the weight of dispersion, of ground calcium carbonate particles of which at least 87% by weight are less than 2 μm in size and then storing the dispersion, and in which the stored dispersion includes, as a dispersing agent, a copolymer of from 5 to 75% by weight AMPS and 95 to 25% by weight acrylic acid, or a water soluble salt thereof, having a molecular weight in the range 1000 to 20,000, and the dispersion remains as a flowable dispersion during the said storage.
Claim 13
Dependent Claim
14 words
A method according to claim 9 in which the milling is by sand grinding.
Claim 14
Dependent Claim
16 words
A method according to claim 9 in which the said copolymer is present throughout the milling.
Claim 15
Dependent Claim
23 words
A method according to claim 9 in which the amount of the said copolymer in the stored dispersion is from 0.01 to 1%.
Claim 16
Dependent Claim
23 words
A method according to claim 9 in which the calcium carbonate content of the filtered dispersion is from 74 to 80% by weight.
Claim 17
Dependent Claim
20 words
A method according to claim 9 in which the said copolymer has a molecular weight of from 2000 to 6000.
Claim 18
Dependent Claim
33 words
A method according to claim 9 in which the said copolymer is of 15 to 40% by weight AMPS and 85 to 60% by weight acrylic acid, or a water soluble salt thereof.
Claim 19
Dependent Claim
19 words
A method according to claim 9 in which the said copolymer is present as the sodium or ammonium salt.
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) | 1988-04-08 | 1988-10-08 | 1989-04-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-04-08 | 1992-10-08 | 1993-04-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-04-08 | 1996-10-08 | 1997-04-09 | $7700.00 | Window Closed / Lapsed |