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US5401482A
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Talc substances having specific surface properties and method of manufacture
Assignee: Imerys Talc Luzenac France SAS
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Filing: 1993-03-31
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Granted: 1995-03-28
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Expires: 2013-03-31
Abstract
Abstract The invention relates to talc substances consisting of particles having a sheet structure. These substances are characterised in that each particle has internally the crystalline structure of talc which confers upon it certain specific properties of this mineral (softness, thermal stability) and has hydrophilic surface properties unlike the hydrophobic properties of mineral talc which give rise to useful reactivity. The substances according to the invention have a thermal and chemical stability range similar to that of talc. They can be manufactured by thermal or chemical means under conditions designed to avoid internal conversion of the talc and to effect the surface modifications consisting of replacing inert siloxane bridges by active hydrophilic groups.
Inventors
- 👤 Clauss: Frederic
- 👤 Richard Baeza
- 👤 Yves Pietrasanta
- 👤 Alain Rousseau
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 12:38
CPC Classifications
C; C01; C01B; C01B33/00; C01B33/20; C01B33/22; C09; C09C; C09C1/00; C09C1/28; C01P; C01P2002/00; C01P2002/70; C01P2002/72; C01P2002/74; C01P2002/80; C01P2002/82; C01P2004/00; C01P2004/20; C01P2004/60; C01P2004/61; C01P2006/00; C01P2006/12; C01P2006/13; C01P2006/60; C01P2006/90
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
70 words
A method for the manufacture of a talc substance consisting of particles having a sheet structure, each particle comprising an internal crystalline structure and at least one hydrophilic surface, said method comprising heating talc particles, to a temperature below 900° C. under conditions such as to avoid conversion of the talc into enstatite and in order to effect a surface modification consisting of substituting inert siloxane groups by active silanols.
Claim 2
Independent Claim
70 words
A method for the manufacture of a talc substance consisting of particles having a sheet structure, each particle comprising an internal crystalline structure and at least one hydrophilic surface, said method comprising heating talc particles, to a temperature below 900° C. under conditions such as to avoid conversion of the talc into enstatite and in order to effect a surface modification consisting of substituting inert siloxane groups by active silanols.
Claim 3
Dependent Claim
29 words
A method according to claim 1, wherein the talc particles are heated to a temperature between 800° C. and 900° C. for a time of at least 10 minutes.
Claim 4
Independent Claim
77 words
A method for the manufacture of a talc substance comprising: heating talc particles in an autoclave at a temperature of at least 150° C. in a reaction medium including water and a water-soluble mineral base, holding the reaction medium at temperature in the autoclave for a time sufficient to effect hydrolysis of a proportion of siloxane groups present at the surface of the talc particles, after cooling, filtering the reaction medium to separate out a solid phase.
Claim 5
Independent Claim
77 words
A method for the manufacture of a talc substance comprising: heating talc particles in an autoclave at a temperature of at least 150° C. in a reaction medium including water and a water-soluble mineral base, holding the reaction medium at temperature in the autoclave for a time sufficient to effect hydrolysis of a proportion of siloxane groups present at the surface of the talc particles, after cooling, filtering the reaction medium to separate out a solid phase.
Claim 6
Dependent Claim
104 words
A method of manufacture according to claim 3, wherein: the talc particles are suspended in an alkaline hydroxide solution so that the ratio of the number of moles of hydroxide to the surface area of the particles is greater than 10 -4 mole/m 2 , the reaction medium so obtained is heated to a temperature between 150° C. and 300° C. in the autoclave, the medium is maintained at said temperature in the autoclave for at least 45 minutes, after filtering the solid phase is neutralised by washing with an acid solution and then a neutral solution, and the talc substance obtained is dried.
Claim 7
Independent Claim
85 words
A method for the manufacture of a talc substance comprising: heating talc particles in an autoclave at a temperature of at least 150° C. in a reaction medium including an organic base, holding the reaction medium at temperature in the autoclave for sufficient time to bring about the hydrolysis of a proportion of siloxane groups present on the surface of the talc particles, after cooling, placing the medium in contact with an acid solution and filtering the reaction medium to separate out a solid phase.
Claim 8
Independent Claim
85 words
A method for the manufacture of a talc substance comprising: heating talc particles in an autoclave at a temperature of at least 150° C. in a reaction medium including an organic base, holding the reaction medium at temperature in the autoclave for sufficient time to bring about the hydrolysis of a proportion of siloxane groups present on the surface of the talc particles, after cooling, placing the medium in contact with an acid solution and filtering the reaction medium to separate out a solid phase.
Claim 9
Independent Claim
64 words
A method for the manufacture of a talc substance comprising: suspending talc particles in the presence of a free radical initiator in a liquid medium which is a solvent for said initiator and which can be split up by free radicals produced by the initiator under conditions sufficient to break siloxane bonds at the surface of the particles and replace them by hydrophilic groups.
Claim 10
Independent Claim
64 words
A method for the manufacture of a talc substance comprising: suspending talc particles in the presence of a free radical initiator in a liquid medium which is a solvent for said initiator and which can be split up by free radicals produced by the initiator under conditions sufficient to break siloxane bonds at the surface of the particles and replace them by hydrophilic groups.
Claim 11
Dependent Claim
101 words
A method according to claim 6, wherein: the free radical initiator consists of at least one of the compounds of the following groups is used: diazo compounds, peroxides, organic peroxides, peracids, disulphides, thiourams, xanthogens, tetramethylethane derivatives, a halogenated organic compound or a mixture of halogenated organic compounds or a third solvent containing a thiol which can be decomposed by the free radicals produced by the initiator is used as the solvent, the suspension is heated to a temperature equal to at least the decomposition temperature of the free radical initiator in order to maintain the free radical reaction in the medium.
Claim 12
Independent Claim
52 words
A method for treating a talc substance to confer one or more surface properties upon said talc substance, which comprises: fixing onto hydrophilic sites on the surface of the talc substance molecules which have both a group which fixes onto these sites and one or more groups conferring the property or properties.
Claim 13
Independent Claim
52 words
A method for treating a talc substance to confer one or more surface properties upon said talc substance, which comprises: fixing onto hydrophilic sites on the surface of the talc substance molecules which have both a group which fixes onto these sites and one or more groups conferring the property or properties.
Claim 14
Dependent Claim
46 words
A method of treatment according to claim 8, wherein one of the surface properties is surface reactivity towards a specific organic matrix, and is obtained by fixing molecules having one or more groups which possess an affinity with the organic matrix onto the hydrophilic surface sites.
Claim 15
Dependent Claim
44 words
A method of treatment according to claim 9, wherein molecules of the following families: epoxys, isocyanates, organic acids, acrylic acids, alcohols, acyl chlorides, anhydrides, and organosilanes comprising at least one hydrolyzable group are fixed to the hydrophilic surface sites represented by the silanol groups.
Claim 16
Dependent Claim
27 words
A method of treatment according to claim 8 to obtain a coloured mineral filler, wherein at least one colouring agent is fixed onto the hydrophilic surface sites.
Claim 17
Dependent Claim
32 words
A method of treatment according to claim 8 in order to obtain an active material with a mineral framework wherein at least one active material is fixed onto the hydrophilic surface sites.
Claim 18
Dependent Claim
29 words
A method of treatment according to claim 8 to obtain an electrically conducting mineral substance, wherein an electrically conducting oligomer or polymer is fixed onto the hydrophilic surface sites.
Claim 19
Dependent Claim
10 words
A talc substance produced by the method of claim 8.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1998-03-27 | 1998-09-26 | 1999-03-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-03-27 | 2002-09-26 | 2003-03-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-03-27 | 2006-09-26 | 2007-03-28 | $7700.00 | Window Closed / Lapsed |