EP0260664A2
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EP
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Process for preparing titanium dioxide in the form of spherical particles by hydrolysis of Ti (IV)
Assignee: Montedison SpA
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Filing: 1987-09-15
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Granted: —
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Expires: 2007-09-15
Abstract
Abstract There is described a process for preparing titanium dioxide in the form of spherical particles having a particle size distribution, in terms of dw/dn, of ≦ 2, by hydrolysis of strongly acidic solutions of Ti(IV), wherein the molar ratio SO₄ = /Ti(IV) is at least 1.5, in the presence of cationic polyelectrolytes having a molecular weight of more than 1 million and an ionicity of at least 3 milliequivalents per gram.
Inventors
- 👤 Franco Dr. Montino
- 👤 Giuseppe Dr. Spoto
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 02:57
CPC Classifications
C; C01; C01G; C01G23/00; C01G23/04; C01G23/047; H; H01; H01G; H01G9/00; H01G9/20; H01G9/2027; H01G9/2031; C01G23/053; C01G23/0532; C01P; C01P2004/00; C01P2004/01; C01P2004/04; C01P2004/30; C01P2004/32; C01P2004/60; C01P2004/61; Y; Y02; Y02E; Y02E10/00; Y02E10/50; Y02E10/542
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
119 words
Process for preparing titanium dioxide in the form of spherical particles having diameters ranging from 0.2 to 1.5 µm and a polydispersion index dw/dn ≦2, dw being the average weighed diameter and dn being the average linear diameter of the particles, by hydrolysis of aqueous solutions, strongly acidic due to HCl or H₂SO₄, of Ti(IV) and SO₄ = ions, in which the SO₄ = /Ti(IV) ratio is at least 1.5, in the presence of cationic polyelectrolytes which are soluble under the reaction conditions at concentrations such as not to form a phase separated from the aqueous solution and have an average molecular weight of more than 1 million and an ionicity of at least 3 milliequivalents per gram (meq/g).
Claim 2
Dependent Claim
119 words
Process for preparing titanium dioxide in the form of spherical particles having diameters ranging from 0.2 to 1.5 µm and a polydispersion index dw/dn ≦2, dw being the average weighed diameter and dn being the average linear diameter of the particles, by hydrolysis of aqueous solutions, strongly acidic due to HCl or H₂SO₄, of Ti(IV) and SO₄ = ions, in which the SO₄ = /Ti(IV) ratio is at least 1.5, in the presence of cationic polyelectrolytes which are soluble under the reaction conditions at concentrations such as not to form a phase separated from the aqueous solution and have an average molecular weight of more than 1 million and an ionicity of at least 3 milliequivalents per gram (meq/g).
Claim 3
Dependent Claim
12 words
Process according to claim 1, wherein the polydispersion index dw/dn is ≦1.20.
Claim 4
Dependent Claim
23 words
Process according to any of claims 1 and 2, wherein the Ti(IV) concentration in the starting solution ranges from 0.05 to 0.25 moles/l.
Claim 5
Dependent Claim
23 words
Process according to any of claims 1 to 3, wherein the Ti(IV) concentration in the starting solution ranges from 0.1 to 0.2 moles/l.
Claim 6
Dependent Claim
31 words
Process according to any of claims 1 to 4, wherein the cationic polyelectrolytes have an ionicity of more than 3.5 meq/g and an average molecular weight of more than 3 million.
Claim 7
Dependent Claim
43 words
Process according to any of claims 1 to 5, wherein the cationic polyelectrolyte is employed in amounts of more than 3% by weight with respect to the theoretical amount of titanium dioxide corresponding to the amount of titanium present in the starting solution.
Claim 8
Dependent Claim
64 words
Process according to any of claims 1 to 6, wherein the cationic polyelectrolyte comprises repeating units based on substituted acrylamide having the general formula: wherein R₁, R₂, R₃ and T are the same or different and are selected from hydrogen and hydrocarbon radicals having 1 to 4 carbon atoms; Z, Y are -CH₃ or H, X is an anion, and n is an integer.
Claim 9
Dependent Claim
29 words
Process according to claim 7, wherein Y, Z and R₃ are H, and R₁ and R₂ are the same or different and are selected from H, -CH₃ and -C₂H₅.
Claim 10
Dependent Claim
44 words
Process according to any of claims 1 to 6, wherein the cationic polyelectrolyte comprises repeating units based on vinylamine having the general formula: wherein R₄, R₅ and R₆ have the same meanings as R₁ defined above and Y and n are as defined above.
Claim 11
Dependent Claim
25 words
Process according to claim 9, wherein R₄ is H, and R₅ and R₆ are the same or different and are selected from H, -CH₃, -C₂H₅.
Claim 12
Dependent Claim
51 words
Process according to any of claims 7 and 8, wherein the polyelectrolyte, in addition to the ionic units, also comprises neutral units derived from unsubstituted acrylamide which have the general formula: wherein Y is as defined above; the ionic units and the neutral units being statistically distributed along the polymer chain.
Claim 13
Dependent Claim
38 words
Process according to any of claims 7 and 8, wherein the cationic polyelectrolyte consists of a copolymer comprising the positively charged units mentioned above and neutral units other than the acrylamide units, statistically distributed along the polymer chain.
Claim 14
Dependent Claim
52 words
Process according to claim 12, wherein the neutral units are selected from the following classes: wherein R is H or a hydrocarbon radical having 1 to 4 carbon atoms; wherein R₇ is the same as R; wherein R₈ is the same as R; wherein R₉ and R₁₀ are the same as R;
Claim 15
Dependent Claim
28 words
Process according to any of claims 1 to 13, wherein the hydrolysis is carried out at temperatures ranging from 90°C to the reflux temperature of the starting solution.
Claim 16
Dependent Claim
16 words
Hydrated titanium dioxide as abtained by the process according to any of claims 1 to 14.
References Cited (Backward Citations)
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