 Microemulsion polymer blends |
| OF THE INVENTION Microemulsions are isotropic dispersions of immiscible fluids, generally oil and ... |
|
| Process for preparing desacetoxycephalosporins |
| OF THE INVENTION Broadly, this invention relates to novel silyl ester compounds produced from ... |
|
| Electrode and method for laryngeal electromyography |
| We claim: 1. An electrode for laryngeal electromyography comprising: (a) an electrical insulator ... |
|
| Hairdressings |
| What we claim is: 1. A hairdressing composition for holding and imparting lustre to the hair ... |
|
| Medicament with a delayed release of active ingredient |
| I claim: 1. A medicament exhibiting a delayed release of active ingredient in the form of hard ... |
|
| Dentifrice-compatible silica particulates |
| OF THE PREFERRED EMBODIMENTS OF THE INVENTION The invention includes several embodiments of novel ... |
|
| Process and an apparatus for the development of photographic two-sheet diffusion materials |
| Proceeding from a process of the initially mentioned type, this object is achieved for a process in ... |
|
| Method of manufacturing semiconductor devices |
| What is claimed is: 1. A method of making semiconductor devices comprising the steps of: a. ... |
|
| Method of producing low carbon tin-mill gage steel without annealing border |
| We claim: 1. In the process for producing a cold rolled tin-mill gage steel coil wherein a low-... |
|
| Apparatus for producing methane gas by processing waste materials |
| This invention utilizes a plurality of tanks. Each of the tanks is covered with a floating hood ... |
|
|
Method for producing small hollow spheres
| Details |
Inventors: Rosencwaig, Allen; Koo, Jackson C.; Dressler, John L.;
Assignee: The United States of America as represented by the United States (Washington, DC)
Primary Examiner: Lindsay, Jr.; Robert L.
Assistant Examiner:
Attorney, Agent or Firm: Carnahan; L. E., Gaither; Roger S., Besha; Richard G.
A method for producing small hollow spheres of glass having an outer diameter ranging from about 100.mu. to about 500.mu. with a substantially uniform wall thickness in the range of about 0.5-20.mu.. The method involves introducing aqueous droplets of a glass-forming solution into a long vertical drop oven or furnace having varying temperature regions. In one embodiment, one of the temperature regions is lower than both the preceeding region and the subsequent region. One region utilizes a temperature of at least 200.degree. C. higher than the melting point of the glass-forming material in the solution and, for example, may be at least 3 times higher than the temperature of the preceeding region. In addition, there is a sharp temperature gradient between these regions. As each droplet of solution passes through a first region it forms into a gel membrane having a spherical shape and encapsulates the rest of the drop retained in the elastic outer surface and the water entrapped within diffuses rapidly through the thin gel membrane which causes more of the glass-forming material to go out of solution and is incorporated into the gel membrane causing it to grow in size and become hollow. thus produced hollow glass sphere has a sphericity, concentricity, and wall uniformity of better than 5%. The sphere is capable of retaining material of up to at least 100 atmospheres therein over long periods of time. In one embodiment. |
|
DETAILED DESCRIPTION The present invention provides an improved method for fabricating higher quality glass microspheres than those produced by the method and apparatus described in above-referenced U.
S.
Pat.
No.
4,133,854.
The method of this invention is particularly applicable for forming glass microspheres having a diameter of about 100-350.
mu.
although microspheres up to about 500.
mu.
can be produced thereby.
The improvement may utilize glass-forming solutions with or without a blowing agent.
In the improved method one stage of the oven is at a substantially higher temperature (at least 200.
degree.
C.
higher than the melting point of the glass-forming material in the solution and, for example, on the order of three times the temperature of the previous stage depending on the composition of the solution) than the preceeding stage, with a sharp temperature gradient between these two stages.
This results in a higher quality glass microsphere than that produced by the method of the above-referenced patent which does not utilize the significant temperature increase and gradient between these two stages.
The present invention utilizes either a three (3) region or a four (4) region or zone vertical oven having specific lengths and temperatures in each region thereof.
By controlling the glass-forming solution composition and the size of the liquid droplet passing through the multiple region vertical oven, and by cooling the temperature and transit time through each region of the oven, it is possible to control the diameter and wall thickness distributions of the resultant microspheres.
|
| Related patents |
|
|
Method for manufacture of powder composition for cordierite
What is claimed is: 1. A method for the manufacture of a powder composition for cordierite, which comprises preparing water containing a water-soluble magnesium salt, a ...
|
|
|
Hollow proppants and a process for their manufacture
OF THE PREFERRED EMBODIMENTS Reference is hereby made to the drawings that illustrate that which is presently regarded as the best mode for carrying out the invention. A...
|
|
|
Annular eddy current test coil with magnetic laminations adjacent a limited circumferential extent
What is claimed is: 1. A magnetic pole and coil assembly for limiting and concentrating eddy currents in a peripheral arc portion of a metal product, the assembly ...
|
|
|
Magnetic resonance imaging of high velocity flows
In accordance with one aspect of the present invention, a method is provided for magnetic resonance phase mapping of moving substances. A pre-inversion of magnetization ...
|
|
|
Cephalosporin derivatives and use as antimicrobial agents
What we claim is: 1. Compounds of formula I, ##STR40## in which R.sub.1 is hydrogen, alkyl, phenylalkyl, carbalkoxyalkyl, C.sub.2-5 alkanoyl, alkoxy-carbonyl, ...
|
|
|
Contact assembly
According to the present invention, a contact assembly is provided for receiving a plurality of male terminals of a modular circuit package. The contact assembly ...
|
|
|
3-Heterothio[(thioalkyl)thioacetyl]cephalosporanic derivatives
OF THE INVENTION The various groups represented by the symbols have the meanings defined below and these definitions are retained throughout this specification. The ...
|
|
|
Process of manufacturing a heat-resistant composite sheet
A polypropylene foam sheet 1 of about 4 mm thickness, and a polyvinyl chloride type leather sheet 3 of about 0.5 mm thickness are taken as the materials to be laminated ...
|
|
|
One-part moisture-curable polyurethane adhesive, coating, and sealant compositions
The prepolymer (a) is derived from certain precursors, such precursors being 4,4'-diphenylmethane diisocyanate or isocyanate-functional derivative(s) thereof and one or ...
|
|
|
Primer and sealant for glass and coated metal
We claim: 1. A method for joining and sealing a coated metal surface to a glass surface which comprises: (a) applying a primer to said metal surface and said glass ...
|
|
|
Semiconductor manufacture 
