Abstract: A fire retardant, intumescent composition is provided which comprises a mixture of alkali metal silicate, represented by the formula M.sub.2 O:xSiO.sub.2 in which M is the alkali metal; an oxy boron compound selected from boric acid or salts of Group I and II elements; and water; in which the weight ratio x ranges from about 1.5 to about 4, the molar ratio of boron to M is between 0.2 and 0.9, and the water comprises about 5 to 15 weight percent of the total composition. These compositions are made by mixing an alkali metal silicate sol with a borate (e.g., boric acid) to form a gel which is dried in an oven. The resulting residue is crumbled to granules. A fire retardant which is relatively insoluble and has improved stability to long term exposure to water and humidity is formed. Various parameters (e.g.
Type:
Grant
Filed:
May 3, 1984
Date of Patent:
June 4, 1985
Assignee:
Minnesota Mining and Manufacturing Company
Inventors:
Joseph Graham, Timothy J. Gennrich, James A. Laird
Abstract: Adhesive, coating, or sealant compositions containing prepolymer(s) derived from MDI (or derivative(s) thereof) and polyol(s) containing primary hydroxyl groups, together with bis[2-N,N-dialkylamino)alkyl]ether(s).
Type:
Grant
Filed:
September 9, 1982
Date of Patent:
April 16, 1985
Assignee:
Minnesota Mining and Manufacturing Company
Abstract: New methods for making "embedded-lens" retroreflective sheeting, and new forms of such sheeting, are provided. The new methods involve embedding microspheres into a web by continuously presenting a mass of the microspheres against the moving web and heating the web so as to soften at least an exterior stratum of the web, and adding a spacing layer to the microsphere-covered surface of the web. The microspheres are embedded on the average to less than 50 percent of their diameter, which has been found to cause the spacing layer to conform around a greater proportion of the back surface of individual microspheres and thereby position a greater portion of the specularly reflective layer carried on the spacing layer at the approximate focal point for light passed through the microspheres. Use of a preformed spacing layer also contributes to maintaining the spacing layer at a constant thickness around the back surface of the microspheres.
Type:
Grant
Filed:
September 16, 1983
Date of Patent:
April 16, 1985
Assignee:
Minnesota Mining and Manufacturing Company
Abstract: A new embedded-lens retroreflective sheeting which exhibits superior properties, including superior angularity, and which is made by a new method of manufacture involving lamination techniques. Microspheres are embedded into a first polymeric layer to less than one-half the average diameter of the microspheres, and a pre-formed spacing film is laminated to the microsphere covered surface of the first layer so as to obtain conformation of the spacing film in a substantially constant thickness over a useful portion of the back surface of the microspheres.
Type:
Grant
Filed:
April 11, 1983
Date of Patent:
March 19, 1985
Assignee:
Minnesota Mining and Manufacturing Company
Abstract: Pavement-marking sheet material which comprises a non-crosslinked elastomeric precursor such as acrylonitrile-butadiene polymer; a thermoplastic polymer such as polyethylene which reinforces the sheet material, e.g., by orientation of the thermoplastic polymer so that the calendered product exhibits greater tensile strength downweb than crossweb; and a particulate inorganic filler, which preferably includes platelet-type fillers such as talc, mica, or magnesium silicate.
Type:
Grant
Filed:
November 1, 1983
Date of Patent:
December 25, 1984
Assignee:
Minnesota Mining and Manufacturing Company
Abstract: A magnetic recording medium having a magnetizable metallic thin-film layer of perpendicular anisotropy can be produced at commercially viable production rates by electrodepositing cobalt, hypophosphite, and preferably also nickel ions at a plating bath temperature of 50.degree.-80.degree. C. and a plating current density of at least 20 mA/cm.sup.2.
Type:
Grant
Filed:
December 20, 1982
Date of Patent:
September 18, 1984
Assignee:
Minnesota Mining and Manufacturing Company
Abstract: An improved design for a compact floppy disk cartridge is provided in which the wiping fabric is prevented from moving and causing stringers out the head access window. This is accomplished by providing ribs on both halves of the cartridge case which, together with raised peripheral edges on the case, provide an irregular shape. The wiping fabric is cut to a shape which conforms with the outline provided by the combination of ribs and peripheral edges. Thus, the wiping fabric is keyed into the space defined by the ribs and peripheral edges.Other improvements embodied in this design are: a compression return spring for a sliding shutter which is substantially completely covered by the shutter (thus preventing debris from interfering with the spring); and temporary interference fit closure of the cartridge shells to permit non-destructive testing.
Type:
Grant
Filed:
November 30, 1983
Date of Patent:
September 4, 1984
Assignee:
Minnesota Mining and Manufacturing Company
Abstract: A narrow range of dinuclear spectral sensitizing dyes can be used in photothermographic silver halide emulsions without adversely affecting fog and speed levels with concentration variations.
Type:
Grant
Filed:
May 13, 1983
Date of Patent:
July 24, 1984
Assignee:
Minnesota Mining and Manufacturing Company
Inventors:
Kenneth W. Metz, Vincent K. Rasbury, Jack E. Reece
Abstract: A thermally developable imaging system comprises a leuco dye, nitrate ion, and a spectrally sensitized organic compound having photolyzable halogen atoms.
Type:
Grant
Filed:
November 8, 1982
Date of Patent:
July 17, 1984
Assignee:
Minnesota Mining and Manufacturing Company
Abstract: The invention relates to a method for preparing 2-lower alkyl-substituted naphthoxazoles by way of non-toxic intermediates, and in particular relates to the preparation of a 2-lower alkyl-naphtho-[2,1-d]-oxazole or a 2-lower alkyl-naphtho-[1,2-d]-oxazole, which are of industrial interest in the field of cyanine dyes for use in photography, and in the field of optical brighteners for use in plastic materials. According to the invention, an aldehyde of a lower alkyl is reacted with 2-nitroso-1-naphthol or with 1-nitroso-2-naphthol, in the presence of a strong acid and a non-aqueous organic solvent, and the condensation product is then reduced.
Type:
Grant
Filed:
October 2, 1980
Date of Patent:
July 17, 1984
Assignee:
Minnesota Mining & Manufacturing Company
Abstract: An article having a primed surface or improved electric charge transfer properties is disclosed. The surface has discrete sites of inorganic materials thereon.
Type:
Grant
Filed:
February 3, 1982
Date of Patent:
June 12, 1984
Assignee:
Minnesota Mining and Manufacturing Company
Inventors:
William A. Hendrickson, Dudley M. Sherman, Hsin-hsin Chou, Vasant V. Kolpe
Abstract: Vapor-sorbing particle-filled sheet material having a low insulation value and useful for providing reduced-stress vapor-sorbing garments. The sheet material comprises at least one permeable support fabric attached to a fibrous web which comprises a coherent mass of melt-blown fibers and vapor-sorptive particles dispersed in the mass of fibers.
Type:
Grant
Filed:
July 23, 1982
Date of Patent:
February 21, 1984
Assignee:
Minnesota Mining and Manufacturing Company
Abstract: Timber support poles are given desired breaking properties to reduce the deceleration of a vehicle that collides with the pole by cutting one or more recesses in the pole, and filling the recesses with a polymeric filler composition.
Type:
Grant
Filed:
January 11, 1982
Date of Patent:
February 21, 1984
Assignee:
Minnesota Mining & Manufacturing Company
Inventors:
Charles R. Kuykendall, Richard B. Castle
Abstract: New sorbent sheet products are prepared comprising a coherent web of entangled blown fibers prepared by extruding liquid fiber-forming material into a high-velocity gaseous stream and an array of super absorbent polymeric particles dispersed within the web.
Type:
Grant
Filed:
March 4, 1982
Date of Patent:
January 31, 1984
Assignee:
Minnesota Mining and Manufacturing Company
Abstract: Coded threads and sheet material for making such threads useful in counterfeit-inhibiting garments. The sheet material comprises transparent microspheres, a specularly reflective layer underlying the microspheres, and a polymeric layer underlying the specularly reflective layer and containing particulate matter which may be varied from sheet material to sheet material to encode information and allow identification of the sheet material. The sheet material is split in narrow widths and incorporated into threads.
Type:
Grant
Filed:
December 7, 1981
Date of Patent:
August 9, 1983
Assignee:
Minnesota Mining and Manufacturing Company
Abstract: Pipe adapted to be installed underwater at increased ocean depths by practical pipe-laying procedures comprises a porous cement shell filled with hollow spheres that are slowly permeable to water under pressure. The cement shell is filled with a sufficient volume of the hollow spheres to make the pipe only slightly heavier than sea water, providing a reduced weight that overcomes previous difficulties in laying pipe at great depths. Over a period of time after the pipe has been installed underwater, the hollow spheres gradually fill with water and make the pipe rest stably on the ocean bottom. The preferred spheres comprise porous core spheres coated with thin coatings that partially seal the spheres to the needed degree of permeability.
Type:
Grant
Filed:
July 19, 1982
Date of Patent:
July 19, 1983
Assignee:
Minnesota Mining and Manufacturing Company
Abstract: Glass bubbles of increased collapse strength are prepared. The bubbles have an average particle density of 0.4 or more and are made of glass that consists essentially of SiO.sub.2 (60-90 weight-percent), alkali metal oxide (2-20 weight-percent), B.sub.2 O.sub.3 (1-30 weight-percent), sulfur (0.005 to 0.5 weight-percent), and other conventional glass-forming ingredients.
Type:
Grant
Filed:
February 25, 1982
Date of Patent:
July 5, 1983
Assignee:
Minnesota Mining and Manufacturing Company
Abstract: Pavement-marking sheet material having protuberances on its upper surface which carry partially exposed microspheres by which the protuberances are made retroreflective and which are separated by recessed areas in which microspheres are fully embedded and not exposed, so as to improve the daytime appearance of the sheet material.
Type:
Grant
Filed:
April 23, 1982
Date of Patent:
June 14, 1983
Assignee:
Minnesota Mining and Manufacturing Company
Abstract: Reflective sheeting useful for application to a pesticide-impregnated animal collar, and animal collars made from the sheeting. The sheeting generally comprises a monolayer of transparent microspheres; specularly reflective material underlying the microspheres; a binder layer of polymeric binder material in which the microspheres are partially embedded; a carrier sheet stretchable about 10 percent or more before rupture, in which the portions of the microspheres protruding from the binder layer are embedded; a barrier layer underlying the binder layer, which sorbs plasticizers more slowly than the binder layer sorbs the plasticizers; and a layer of adhesive underlying the barrier layer.
Type:
Grant
Filed:
September 24, 1981
Date of Patent:
March 29, 1983
Assignee:
Minnesota Mining and Manufacturing Company
Inventors:
Chi F. Tung, James C. Coderre, Chester A. Bacon, Jr.
Abstract: A method for forming a filter of electrically charged electret fiber material, consisting of a high molecular weight, nonpolar polymeric substance, comprising drawing, charging, and fibrillating a foil of said high molecular weight substance. The fibrillated foil is wound and then crimping is effected.
Type:
Grant
Filed:
December 7, 1981
Date of Patent:
June 21, 1983
Assignee:
Minnesota Mining and Manufacturing Company