EP0242208A1
Expired / Lapsed
EP
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Composite membrane
Assignee: Rio Tinto Alcan International Ltd
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Filing: 1987-04-15
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Granted: —
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Expires: 2007-04-15
Abstract
Abstract A composite sheet comprises a porous inorganic membrane and a microporous inorganic film (10) overlying a surface (18) of the membrane, where the membrane may be an anodic aluminium oxide membrane having an average pore diameter of 5 to 100nm, and the microporous film is of substantially uniform pore size and substantially free of cracks and pinholes. The film may be formed by applying a colloidal sol of an aluminium alkoxide, or a solution of a polymeric precursor of a titanium oxide, to a surface of the membrane to form thereon a gel layer, and drying and heating the gel to convert it to a microporous inorganic film.
Inventors
- 👤 Ernest Paul Butler
- 👤 Rowena Roshanthi Landham
- 👤 Michael Patrick Thomas
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-25 08:44
CPC Classifications
B; B01; B01D; B01D69/00; B01D69/12; B01D69/122; B01D67/00; B01D67/0039; B01D67/0046; B01D67/0048; B01D69/125; B01D69/127; B01D71/00; B01D71/02; C; C23; C23C; C23C18/00; C23C18/02; C23C18/12; C23C18/1204; C23C18/1208; C23C18/1216; C23C18/125; C23C18/1254; C25; C25D; C25D11/00; C25D11/02; C25D11/04; C25D11/045; C25D11/18; C25D11/24; C25D11/246; B01D2325/00; B01D2325/04
Claims Analysis
Total Claims: 35
Claim 1
Independent Claim
58 words
A composite sheet comprising a porous inorganic membrane and a microporous inorganic film overlying a surface of the membrane, wherein the porous inorganic membrane has an average pore diameter of 5 to 100nm at the surface overlain by the film, and the microporous inorganic film is of substantially uniform pore size and substantially free of cracks and pinholes.
Claim 2
Dependent Claim
58 words
A composite sheet comprising a porous inorganic membrane and a microporous inorganic film overlying a surface of the membrane, wherein the porous inorganic membrane has an average pore diameter of 5 to 100nm at the surface overlain by the film, and the microporous inorganic film is of substantially uniform pore size and substantially free of cracks and pinholes.
Claim 3
Dependent Claim
46 words
A composite sheet comprising a porous inorganic membrane and a microporous inorganic film overlying a surface of the membrane, wherein the microporous inorganic film has a thickness from 0.01 to 2.0 microns and a substantially uniform pore size and is substantially free of cracks and pinholes.
Claim 4
Dependent Claim
46 words
A composite sheet comprising a porous inorganic membrane and a microporous inorganic film overlying a surface of the membrane, wherein the microporous inorganic film has a thickness from 0.01 to 2.0 microns and a substantially uniform pore size and is substantially free of cracks and pinholes.
Claim 5
Dependent Claim
39 words
A composite sheet comprising a porous anodic aluminium oxide membrane and a microporous inorganic film overlying a surface of the membrane, wherein the microporous inorganic film is of substantially uniform pore size and substantially free of cracks and pinholes.
Claim 6
Dependent Claim
39 words
A composite sheet comprising a porous anodic aluminium oxide membrane and a microporous inorganic film overlying a surface of the membrane, wherein the microporous inorganic film is of substantially uniform pore size and substantially free of cracks and pinholes.
Claim 7
Dependent Claim
19 words
A composite sheet as claimed in claim 1 or claim 2, wherein the porous inorganic membrane is of alumina.
Claim 8
Dependent Claim
18 words
A composite sheet as claimed in claim 4, wherein the alumina membrane is an anodic aluminium oxide membrane.
Claim 9
Dependent Claim
67 words
A composite sheet as claimed in claim 3 or claim 5, wherein the porous anodic oxide membrane is asymmetric by virtue of having a system of larger pores extending in from a first face and a system of smaller pores extending in from a second face, the system of larger pores interconnecting with the system of smaller pores and the microporous inorganic film overlying the second face.
Claim 10
Dependent Claim
26 words
A composite sheet as claimed in any one of claims 1 and 3 to 6, wherein the microporous film is from 0.01 to 2.0 microns thick.
Claim 11
Dependent Claim
23 words
A composite sheet as claimed in any one of claims 1 to 7, wherein the microporous inorganic film is of a metal oxide.
Claim 12
Dependent Claim
16 words
A composite sheet as claimed in claim 8, wherein the microporous inorganic film is of gamma-alumina.
Claim 13
Dependent Claim
27 words
A composite sheet as claimed in any one of claims 1 to 9, wherein the average pore size of the microporous film is from 0.5 to 30nm.
Claim 14
Independent Claim
85 words
A method of making a composite sheet, which method comprises providing a porous inorganic membrane having an average pore diameter of 5 to 100nm at one surface thereof, applying a colloidal sol of an inorganic material or a solution of a polymeric precursor to an inorganic material to the said surface so as to form a gel layer thereon, and drying and heating the gel to convert it to a microporous inorganic film of substantially uniform pore size and substantially free of cracks and pinholes.
Claim 15
Independent Claim
85 words
A method of making a composite sheet, which method comprises providing a porous inorganic membrane having an average pore diameter of 5 to 100nm at one surface thereof, applying a colloidal sol of an inorganic material or a solution of a polymeric precursor to an inorganic material to the said surface so as to form a gel layer thereon, and drying and heating the gel to convert it to a microporous inorganic film of substantially uniform pore size and substantially free of cracks and pinholes.
Claim 16
Independent Claim
79 words
A method of making a composite sheet, which method comprises providing a porous inorganic membrane, applying a colloidal sol of an inorganic material or a solution of a polymeric precursor to an inorganic material to a surface thereof so as to form a gel layer thereon, and drying and heating the gel to convert it to a microporous inorganic film of thickness from 0.1 to 2.0 microns and substantially uniform pore size and substantially free of cracks and pinholes.
Claim 17
Independent Claim
79 words
A method of making a composite sheet, which method comprises providing a porous inorganic membrane, applying a colloidal sol of an inorganic material or a solution of a polymeric precursor to an inorganic material to a surface thereof so as to form a gel layer thereon, and drying and heating the gel to convert it to a microporous inorganic film of thickness from 0.1 to 2.0 microns and substantially uniform pore size and substantially free of cracks and pinholes.
Claim 18
Independent Claim
74 words
A method of making a composite sheet, which method comprises providing a porous anodic aluminium oxide membrane, applying a colloidal sol of an inorganic material or a solution of a polymeric precursor to an inorganic material to a surface thereof so as to form a gel layer thereon and drying and heating the gel to convert it to a microporous inorganic film of substantially uniform pore size and substantially free of cracks and pinholes.
Claim 19
Independent Claim
74 words
A method of making a composite sheet, which method comprises providing a porous anodic aluminium oxide membrane, applying a colloidal sol of an inorganic material or a solution of a polymeric precursor to an inorganic material to a surface thereof so as to form a gel layer thereon and drying and heating the gel to convert it to a microporous inorganic film of substantially uniform pore size and substantially free of cracks and pinholes.
Claim 20
Independent Claim
85 words
A method of making a composite sheet, which method comprises providing a porous inorganic membrane, pretreating a surface thereof with a solution of a silicate, borate or phosphate, applying to the pretreated surface a colloidal sol of an inorganic material or a solution of a polymeric precursor to an inorganic material so as to form thereon a gel layer, and drying and heating the gel to convert it to a microporous inorganic film of substantially uniform pore size and substantially free of cracks and pinholes.
Claim 21
Independent Claim
85 words
A method of making a composite sheet, which method comprises providing a porous inorganic membrane, pretreating a surface thereof with a solution of a silicate, borate or phosphate, applying to the pretreated surface a colloidal sol of an inorganic material or a solution of a polymeric precursor to an inorganic material so as to form thereon a gel layer, and drying and heating the gel to convert it to a microporous inorganic film of substantially uniform pore size and substantially free of cracks and pinholes.
Claim 22
Independent Claim
97 words
A method of making a composite sheet, which method comprises providing a porous inorganic membrane and a colloidal sol of an inorganic material or a solution of a polymeric precursor to an inorganic material, increasing the viscosity of the sol or solution by adding a relatively viscous miscible organic liquid, applying the more viscous sol or solution to a surface of the membrane so as to form thereon a gel layer, and drying and heating the gel to convert it to a microporous inorganic film of substantially uniform pore size and substantially free of cracks and pinholes.
Claim 23
Independent Claim
97 words
A method of making a composite sheet, which method comprises providing a porous inorganic membrane and a colloidal sol of an inorganic material or a solution of a polymeric precursor to an inorganic material, increasing the viscosity of the sol or solution by adding a relatively viscous miscible organic liquid, applying the more viscous sol or solution to a surface of the membrane so as to form thereon a gel layer, and drying and heating the gel to convert it to a microporous inorganic film of substantially uniform pore size and substantially free of cracks and pinholes.
Claim 24
Independent Claim
25 words
A method as claimed in any one of claims 11, 12, 14 and 15, wherein the porous inorganic membrane is an anodic aluminium oxide membrane.
Claim 25
Dependent Claim
67 words
A method as claimed in claim 16, wherein the porous anodic aluminium oxide membrane is asymmetric by virtue of having a system of larger pores extending in from a first face and a system of smaller pores extending in from a second face, the system of larger pores interconnecting with the system of smaller pores, the colloidal sol or the solution being applied to the second face.
Claim 26
Independent Claim
37 words
A method as claimed in any one of claims 11 to 13 or 15, wherein the porous inorganic membrane is of alumina, a surface of which is pre-treated with a solution of a silicate, borate or phosphate.
Claim 27
Dependent Claim
56 words
A method as claimed in claim 14 or claim 18, wherein pretreatment is effected by contacting the porous membrane with an aqueous solution of the silicate, borate or phosphate at a concentration of at least 1% by weight and a temperature of 0 to 50°C for a contact time of from 1 second to 10 minutes.
Claim 28
Independent Claim
34 words
A method as claimed in any one of claims 11 to 19, wherein the colloidal sol is of a refractory metal oxide or the solution is of a polymeric precursor to a metal oxide.
Claim 29
Dependent Claim
22 words
A method as claimed in claim 20, wherein the colloidal sol is a boehmite sol obtained by hydrolysis of an aluminium alkoxide
Claim 30
Dependent Claim
29 words
A method as claimed in claim 20, wherein the solution of a polymeric precursor to a metal oxide is a solution obtained by partial hydrolysis of a titanium alkoxide.
Claim 31
Independent Claim
23 words
A method as claimed in any one of claims 11 to 22, wherein the colloidal sol or solution contains a surface active agent.
Claim 32
Independent Claim
28 words
A method as claimed in any one of claims 11 to 23, wherein the colloidal sol or solution is applied to the porous membrane by an aerosol method.
Claim 33
Independent Claim
27 words
A method as claimed in any one of claims 11 to 23, wherein the colloidal sol or solution is applied to the membrane by a spin-coating method.
Claim 34
Independent Claim
26 words
A method as claimed in any one of claims 11 to 25, used to make the composite sheet of any one of claims 1 to 10.
Claim 35
Dependent Claim
16 words
A filter comprising a composite sheet as claimed in any one of claims 1 to 10.
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