US4775520A
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Spherical SiO2 particles
Assignee: Merck Patent GmbH
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Filing: 1986-09-25
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Granted: 1988-10-04
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Expires: 2006-09-25
Abstract
Abstract Highly monodispersed nonporous spherical SiO 2 particles are prepared having mean particle diameters between 0.05 and 10 μm with a standard deviation of not more than 5% and a method for the preparation of such particles. The particles can be produced by a two step process wherein first a sol of primary particles is prepared by hydrolytic polycondensation of tetraalkoxysilanes in an aqueous/alcoholic ammoniacal medium. The SiO 2 particles are then converted to the desired particle size by a continuous measured addition of tetraalkoxysilane or organotrialkoxysilane controlled by the extent of the reaction. The SiO 2 particles produced by this process are particularly useful as sorption material in chromatography.
Inventors
- 👤 Klaus Unger
- 👤 Herbert Giesche
- 👤 Joachim Kinkel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 04:04
CPC Classifications
B; B01; B01D; B01D15/00; B01D15/08; B01D15/26; B01D15/32; B01D15/325; B82; B82Y; B82Y30/00; B01J; B01J20/00; B01J20/02; B01J20/10; B01J20/103; B01J20/28; B01J20/28002; B01J20/28004; B01J20/28014; B01J20/28016; B01J20/28019; B01J20/28054; B01J20/28057; B01J20/28059; B01J20/281; B01J20/286; B01J20/287; B01J20/30; B01J20/3092; B01J20/32; B01J20/3202; B01J20/3204; B01J20/3214; B01J20/3217; B01J20/3231; B01J20/3242; B01J20/3244; B01J20/3246; B01J20/3257; B01J20/3259; B01J20/3261; C; C01; C01B; C01B33/00; C01B33/113; C01B33/12; C01B33/16; C01B33/163; C01B33/18; B01J2220/00; B01J2220/50; B01J2220/54; B01J2220/58; C01P; C01P2004/00; C01P2004/30; C01P2004/32; C01P2004/51; C01P2004/52; C01P2004/60; C01P2004/61; C01P2004/62; C01P2004/64; C01P2006/00; C01P2006/12
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
65 words
A method for preparing substantially spherical particles consisting essentially of SiO 2 comprising continuously adding to a sol of primary particles formed by hydrolytic polycondensation of a tetraalkoxysilane in an aqueous/alcoholic ammoniacal hydrolysis mixture, an amount of a tetraalkoxysilane sufficient to lower the porosity of the particles in the sol, said continuous addition being effected at a rate whereby substantially no additional particles are formed.
Claim 2
Independent Claim
65 words
A method for preparing substantially spherical particles consisting essentially of SiO 2 comprising continuously adding to a sol of primary particles formed by hydrolytic polycondensation of a tetraalkoxysilane in an aqueous/alcoholic ammoniacal hydrolysis mixture, an amount of a tetraalkoxysilane sufficient to lower the porosity of the particles in the sol, said continuous addition being effected at a rate whereby substantially no additional particles are formed.
Claim 3
Dependent Claim
25 words
A method of claim 1, wherein the amount of silane added to the sol is controlled to directly control a resultant increase in particle size.
Claim 4
Dependent Claim
38 words
A method according to claim 2, wherein the sol of primary particles are converted to substantially nonporous particles having a mean particle diameter of about 0.05 to 10 μm with a standard deviation of not more than 5%.
Claim 5
Dependent Claim
27 words
A method according to claim 1, wherein the sol of primary particles is formed by addition in batch form of a tetraalkoxysilane to the aqueous/alcoholic ammoniacal mixture.
Claim 6
Dependent Claim
20 words
A method according to claim 1, wherein the hydrolytic polycondensation is performed at temperatures of about 35° to 75° C.
Claim 7
Dependent Claim
21 words
A method according to claim 4, wherein the hydrolytic polycondensation is performed at a temperature of about 40° to 65° C.
Claim 8
Dependent Claim
19 words
A method according to claim 1, wherein the tetraalkoxysilane is a silicate ester of a C 1-3 aliphatic alcohol.
Claim 9
Dependent Claim
11 words
A method according to claim 1, wherein the tetraalkoxysilane is tetraethoxysilane.
Claim 10
Dependent Claim
31 words
A method according to claim 1, wherein an organotrialkoxysilane is also added during the addition of the tetraalkoxysilane whereby SiO 2 particles are produced having surfaces modified by said organo groups.
Claim 11
Dependent Claim
24 words
A method according to claim 2, wherein the surface area of the particles formed is about 1 to 1.5 times their theoretical surface area.
Claim 12
Dependent Claim
18 words
A method according to claim 1, wherein additional aqueous/alcoholic ammoniacal hydrolysis mixture is added during said continuous addition.
Claim 13
Dependent Claim
23 words
A method of claim 1, further comprising prior to said continuous addition step, carrying out said hydrolytic polycondensation step to prepare said sol.
Claim 14
Dependent Claim
20 words
A method according to claim 1, wherein said continuous measured addition is performed at a temperature of about 40° C.
Claim 15
Independent Claim
70 words
A method of lowering the porosity of particles consisting essentially of SiO 2 prepared by hydrolytic polycondensation of a tetraalkoxysilane in an aqueous/alcoholic ammoniacal hydrolysis mixture to form a sol of said particles, comprising continuously adding to said sol an amount of a tetraalkoxysilane sufficient to lower the porosity of the particles in the sol, said continuous addition being effected at a rate whereby substantially no additional particles are formed.
Claim 16
Independent Claim
70 words
A method of lowering the porosity of particles consisting essentially of SiO 2 prepared by hydrolytic polycondensation of a tetraalkoxysilane in an aqueous/alcoholic ammoniacal hydrolysis mixture to form a sol of said particles, comprising continuously adding to said sol an amount of a tetraalkoxysilane sufficient to lower the porosity of the particles in the sol, said continuous addition being effected at a rate whereby substantially no additional particles are formed.
Claim 17
Independent Claim
71 words
A method for preparing substantially spherical particles consisting essentially of SiO 2 comprising continuously adding to a sol of primary particles formed by hydrolytic polycondensation of a tetraalkoxysilane in an aqueous/alcoholic ammoniacal hydrolysis mixture, an amount of a tetraalkoxysilane, an organotrialkoxysilane or a combination thereof, sufficient to lower the porosity of the particles in the sol, said continuous addition being effected at a rate whereby substantially no additional particles are formed.
Claim 18
Independent Claim
71 words
A method for preparing substantially spherical particles consisting essentially of SiO 2 comprising continuously adding to a sol of primary particles formed by hydrolytic polycondensation of a tetraalkoxysilane in an aqueous/alcoholic ammoniacal hydrolysis mixture, an amount of a tetraalkoxysilane, an organotrialkoxysilane or a combination thereof, sufficient to lower the porosity of the particles in the sol, said continuous addition being effected at a rate whereby substantially no additional particles are formed.
Claim 19
Dependent Claim
24 words
A method according to claim 3, wherein the surface area of the particles formed is about 1 to 1.5 times their theoretical surface area.
Claim 20
Dependent Claim
23 words
A method according to claim 9, wherein said substantially spherical SiO 2 particles consist essentially of an SiO 2 matrix containing organic groups.
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