 Wear and thermal shock resistant SiAlON cutting tool material |
| It is an object of this invention to avoid or alleviate the problems of the prior art. It is ... |
|
| Method of preparing crystalline zeolitic aluminosilicates |
| What is claimed is: 1. In a method of preparing crystalline ZSM-5 or ZSM 11 zeolites with an atomic ... |
|
| Small crystal ZSM-5, as a catalyst |
| OF THE INVENTION In one embodiment of the invention, a component of the crystallization reaction ... |
|
| Synthesis process for faujasite family zeolites using mother liquor recycle |
| What is claimed is: 1. A process for preparing an aluminosilicate having a faujasite family ... |
|
| Method for preparing [F-18-]fluoride ion |
| OF THE INVENTION According to the present invention, there is provided a method for preparing [F-18... |
|
| Method for casting ultrathin methylpentene polymer membranes |
| OF THE INVENTION AND MANNER AND PROCESS OF MAKING AND USING IT Film-forming MPP-containing ... |
|
| Ionic complex for enhancing performance of water treatment membranes |
| OF THE INVENTION The ionic complex which constitutes a discriminating layer of the membranes of ... |
|
| Asymmetric semipermeable membrane for the treatment of biological fluids |
| An objective of the present invention is to provide an improved semipermeable membrane suitable for ... |
|
| Automatic lancet device and method of using the same |
| OF THE INVENTION Referring first to FIGS. 1A, 1B, and 1C, there is shown a simplified elevation ... |
|
| Compact, integrated electron beam imaging system |
| OF THE INVENTION Referring now to FIG. 1, an electron beam imaging system constructed in ... |
|
|
Asymmetric porous polyamide membranes
| Details |
Inventors: Dennison, Kathleen A.; Kolcinski, Bruce E.; Krishnan, Subramanian; Russell, Patrise M.;
Assignee: Minnesota Mining and Manufacturing Company (St. Paul, MN)
Primary Examiner: Sever; Frank
Assistant Examiner:
Attorney, Agent or Firm: Griswold; Gary L., Kirn; Walter N., Maki; Eloise J.
Asymmatric, porous polyamide membranes permeable to fluid flow comprising: (A) a porous skin layer, and (B) adjacent to the skin layer, an integral, porous support layer having at least one region comprising a network of substantially parallel, hollow tube-like structures, each of the tube-like structures being oriented such that the longitudinal dimension of each tube-like structure is essentially perpendicular to the skin layer; wherein the skin layer is relatively thin and dense compared to the support layer, the pore diameters in the skin layer are relatively small compared to the diameters of the tube-like structures in the support layer, in membrances having support layers with more than one region, the cross-sectional area of the tube-like structures is larger in regions located farther from the skin layer, and the polyamide is an aliphatic polyamide having a glass transition temperature of less than 200.degree. C., and method of making the same. These membranes are useful in ultrafiltration and microfiltration processes. |
|
DETAILED DESCRIPTION This invention provides an asymmetric, porous polyamide membrane permeable to fluid flow comprising: (A) a porous skin layer, and (B) adjacent to the skin layer, an integral, porous support layer (i.
e.
, a support layer formed in the same operation or step and having substantially the same composition as the skin layer) having at least one region comprising a network of substantially parallel, hollow tube-like structures, each of the tube-like structures being oriented such that the longitudinal dimension of each tube-like structure is essentially perpendicular to the skin layer; wherein: the skin layer is relatively thin and dense compared to the support layer, the pore diameters in the skin layer are relatively small compared to the diameters of the tube-like structures in the support layer, and in membranes having support layers with more than one region, the cross-sectional area of the tube-like structures is larger in regions located farther from the skin layer, and the polyamide is an aliphatic polyamide having a glass transition temperature of less than 200.
degree.
C.
This invention further provides supported asymmetric membranes, i.
e.
, membranes comprising the polyamide membrane described above and a preformed, porous, support layer, e.
g.
non-woven web, woven cloth or paper, having two parallel surfaces.
This invention also provides a method of preparing the asymmetric and supported asymmetric membranes described above comprising the steps of: (a) preparing a casting solution comprising the polyamide dissolved in an alcohol/salt solution; (b) coating a film of preselected thickness of the casting solution onto the surface of a casting substrate (e.
g.
a TEFLON-coated surface, glass, or polyethylene terephthalate) or coating a film of preselected thickness of the casting solution onto one or both of the parallel surfaces of a preformed, porous support material and placing the resulting coated preformed support on a casting substrate, or (c) extruding a hollow fiber of the casting solution through an annular die; (d) immersing the resulting film, coated preformed support, or hollow fiber in a liquid non-solvent bath thereby precipitating the polyamide and forming an asymmetric polyamide membrane or asymmetric, supported polyamide membrane, and recovering the membrane or supported membrane from the non-solvent bath and drying it
|
|
Semiconductor manufacture 
