Abstract: A method of preparing abrasive articles exhibiting improved homogeneity and breakdown properties is disclosed. The method comprises admixing abrasive grits and a bond phase comprising silica particles, alumina, a flux and water, to form a slurry, such that the silica particles are on the average smaller than the average grit particles; drying the slurry to form a precursor powder; and compacting the precursor powder to form an abrasive greenware article. This abrasive greenware article can then be densified, for example, by sintering, to form a densified abrasive article. The resulting abrasive article has a porcelain bond composition. Because of the uniform bond composition attained with this invention, extremely fine abrasive grits can be employed.
Abstract: A process for preparing a self-reinforced silicon nitride ceramic body of high fracture toughness comprising hot-pressing a powder mixture containing silicon nitride, magnesium oxide, yttrium oxide and calcium oxide under conditions such that densification and the in situ formation of .beta.-silicon nitride whiskers having a high aspect ratio occur. A novel silicon nitride ceramic of high fracture toughness is disclosed comprising a .beta.-silicon nitride crystalline phase wherein at least about 20 volume percent of the phase is in the form of whiskers having an average aspect ratio of at least about 2.5; a glassy second phase containing magnesium oxide, yttrium oxide, calcium oxide, and silica in a total amount not greater than about 35 weight percent; and not greater than about 10 weight percent of the total weight as other phases.
Type:
Grant
Filed:
February 28, 1989
Date of Patent:
April 24, 1990
Assignee:
The Dow Chemical Company
Inventors:
Aleksander J. Pyzik, Douglas B. Schwarz, William J. Dubensky, Donald R. Beaman
Abstract: A liquid chromatographic method and apparatus is disclosed which employs an improved pump not requiring driven pistons or sliding seals. The pump comprises at least one length of tubing forming a chamber disposed between first and second check valves, controllable heating means to periodically heat liquid in said chamber effective to pump relatively low volumes of liquid from the chamber at relatively high pressures, means for measuring the pressure developed by the pump, and control means to increase and decrease the amount of heat imparted to the liquid to maintain the pump operation at a controlled pressure setpoint.
Type:
Grant
Filed:
October 27, 1988
Date of Patent:
April 17, 1990
Assignee:
The Dow Chemical Company
Inventors:
Theodore E. Miller, Jr., Charles M. Davis
Abstract: A combination electrolysis cell seal member and electrolysis cell frame cover member suitable for use as a gasket/cover member in an electrolytic cell of the filter press type. The gasket/cover member used for a filter press-type electrolytic cell includes two gasket/cover load-bearing sections integral with a peripheral frame cover section. The gasket load-bearing sections contains a first and second side. The first side contacts a electrolysis cell membrane member and the second side contacts an electrolysis cell frame member. The membrane is interposed between two electrolysis cell frame members each having a gasket/cover member secured thereto.
Abstract: Alkenyl aromatic thermoplastic synthetic resinous elongate foam bodies having a machine direction, a traverse direction and closed noninterconnecting gas-containing cells are prepared using 1,1-difluoro-1-chloroethane as a blowing agent. These foam bodies have an average cell size of 0.05 to 2.0 millimeters, a minimum cross-sectional dimension of at least 0.25 inch, a cross-sectional area of at least 8 square inches, a water vapor permeability not greater than 1.8 perm inch, a density not exceeding 2.4 pounds per cubic foot, and an absolute dimensional stability of less than 4 percent in any direction when measured by the test designated ASTM D2126/C578. Also disclosed is a method for preparing such foam bodies, other alkenyl aromatic thermoplastic synthetic resinous elongate foam bodies having the same criteria, except a density from 2.4 to 5.0 pounds per cubic foot and a method for preparing such greater density foam bodies.
Abstract: Disclosed is an apparatus for introducing a gusset into a web of plastic film. The apparatus includes a pneumatically-biased protruding plate which varies the depth of the gusset to maintain a constant protruding plate-film web tension in response to variations in the transverse width of the film web. Further disclosed is a means for holding the zipper laterally stationary and in alignment while the gusset is introduced into the film web by the same apparatus.
Abstract: A method for cyanoisoalkylating phenols or other hydroxy-substituted aryl compounds, which may have up to two substitutents ortho or para to the hydroxy moiety, comprising reacting a molar excess of phenol or aryl compound with a ketone in the presence of cyanide ion and hydroxide ion at an elevated temperature.Compounds, such as 4-(1-cyano-1-methylethyl)phenol, produced via this method are useful as chemical intermediates in the preparation of polyurethanes, epoxy resins and pharmaceutical and agricultural products.
Abstract: The invention is a pressure sensing device utilizing a polymer optical fiber with a core comprised of a flexible thermoplastic aliphatic segmented polyurethane. The use of an optical fiber based pressure sensor eliminates the electromagnetic interference problems associated with conventional electronic pressure sensors. Use of polyurethane as the core material for the optical fiber results in an optical fiber with high flexibility, thus making the inventive pressure sensing device more rugged and durable than other optical fiber based pressure sensors.
Abstract: This invention relates to novel polymeric polyamines containing internal urea, biuret, thiourea, dithiobiuret, and/or thioamide moieties, and to polymers prepared therefrom. This invention also relates to novel isocyanate-functional prepolymers containing urea, biuret, amide, thiourea, dithiobiuret, and/or thioamide moieties and to polymers prepared therefrom.
Abstract: A casting process for the preparation of whiteware ceramic articles employs a polyalkylene polyamine, such as tetraethylene pentamine, as an additive to increase the casting rate. The additive can be employed, e.g., in slip casting, vacuum casting and pressure casting. Optionally, the addtive includes a binder such as a styrene butadiene latex in an amount effective to maintain the green strength of the articles prepared in the casting process.
Type:
Grant
Filed:
June 1, 1988
Date of Patent:
April 10, 1990
Assignee:
The Dow Chemical Company
Inventors:
Brian D. Koblinski, Alfredo C. Tamez, Alan P. Croft
Abstract: The present invention provides an apparatus for generating a reagent of sulfur trioxide in a carrier which includes a reagent generator. The reagent generator has associated therewith means for introducing a source of sulfur trioxide into the reagent generator, means for introducing a carrier such as a liquid halocarbon or an inert gas into the reagent generator, and means for introducing oleum into the reagent generator. The reagent generator also includes means for contacting the sulfur trioxide, carrier, and oleum to provide a reagent of sulfur trioxide in the carrier. Additionally, the system includes means for removing oleum from the reagent generator, as well as means for removing the reagent from the reagent generator. In a preferred embodiment, the system for generating the reagent also includes, in conjunction with the reagent generator, a treatment chamber for the surface treatment of polymer resins including medical products which have polymeric resin material on exposed surfaces thereof.
Abstract: A method of thickening a food product which substantially maintains the viscosity of food products when they are heated to elevated temperatures. The method comprises using specific methylcelluloses in combination with various food approved starches.
Abstract: A composite comprising a functional fluoropolymer having pendant groups which terminate with a second reacting group and a first substrate having a first reacting groups, wherein at least a portion of the first reacting groups and at least a portion of the second reacting groups have reacted with each other to form covalent or ionic bonds.
Abstract: Paramethyl-substituted hindered phenols are selectively oxidized by contacting with an oxidizing agent at elevated temperatures in the presence of a heterogeneous oxidative coupling catalyst. In the absence of an optional nucleophile the products comprise carbon-carbon oxidative coupling products. In the presence of a nucleophile, addition products result that may be further oxidized by continued exposure to the oxidizing agent to yield substituted p-hydroxybenzaldehydes.
Abstract: Adducts of metabrominated monophenols such as 3,5-dibromo-2,4,6-trimethylphenol and multifunctional epoxides such as cresol-formaldehyde epoxy novolac resins are disclosed to be useful in formulations for encapsulating electronic components.
Abstract: A chromatographic method for the determination of individual phenols in water by adding a halogenating agent to the water, e.g., using the bromate-bromide reaction to generate tribromide ions which react with the phenols to form bromo-derivatives of the phenols, then to permeate the bromo-derivatives across a membrane, e.g., a silicone rubber membrane, into a liquid extractant, e.g., a dilute aqueous solution of sodium hydroxide and acetonitrile, and then determining the permeated bromo-derivatives in the liquid extractant by chromatography, e.g., by injecting the liquid extractant containing the permeated bromo-derivatives into a reverse phase liquid chromatographic system.
Abstract: A process and apparatus for severing and simultaneously sealing a plurality of plies of thermoplastic material to form bags for storing foods therein is provided. A severing and sealing element fabricated from a long range ordered alloy is used. The use of that alloy provides increased element life at higher operating temperatures while significantly reducing odor and off-flavor problems in the bags.
Type:
Grant
Filed:
November 23, 1988
Date of Patent:
April 3, 1990
Assignee:
The Dow Chemical Company
Inventors:
Patrick M. Russell, Roger K. Pihlaja, Timothy R. Woods
Abstract: Substrates having successive layers of a cellular polyurethane and a noncellular polyurethane are prepared using certain siloxane-polyether block copolymers in the noncellular polyurethane formulation. The use of the block copolymer reduces or eliminates the formation of a bubble line at the interface of the polyurethane layers, thereby improving physical and cosmetic properties of the carpet.
Type:
Grant
Filed:
June 29, 1989
Date of Patent:
April 3, 1990
Assignee:
The Dow Chemical Company
Inventors:
Kenneth W. Skaggs, Robert B. Turner, Terry L. Lamb
Abstract: This invention relates to a process for preparing polyisocyanate-based polymers which have the ability to dissipate static electrical charge. The polymers are rendered semi-conductive by having incorporated into them an anti-static additive which comprises an ionizable metal salt dispersed in a polyalkylene carbonate polyol.
Abstract: This invention relates to binary thermoplastic polyblend consisting essentially of a thermoplastic aromatic polycarbonate and a thermoplastic polyester polyol-based polyurethane (TPU). The polyblends exhibit improved hydrocarbon solvent resistance and melt flow properties over polycarbonate resins.