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Robert P Arens, Russell D Birkholz, Dee Lynn Johnson, Theodore P Labuza, Curtis L Larson, David J Yarusso: Time-temperature integrating indicator device. Minnesota Mining and Manufacturing Company, Gary L Griswold, Walter N Kirn, James J Trussell, September 16, 1997: US05667303 (106 worldwide citation)

A selectively activated time-temperature integrating device for providing a visually observable indication of cumulative thermal exposure, in which a viscoelastic material migrates into a diffusely light-reflective porous matrix at a rate which varies with temperature to progressively change the lig ...


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Robert P Arens: Reusable bingo card. Minnesota Mining and Manufacturing Company, Donald M Sell, Walter N Kirn, Richard E Brink, October 31, 1989: US04877253 (33 worldwide citation)

A reusable bingo card comprising an exposed microporous layer having bingo numbers permanently imprinted thereon, and a liquid impervious support sheet bonded to the exposed layer. The support sheet is substantially darker than the background area of the exposed layer. To mark a number on the card a ...


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Robert P Arens, James M Ripka: Article for use in forming a permanent image using a temporary marker. Minnesota Mining and Manufacturing Company, Gary L Griswold, Walter N Kirn, Leland D Schultz, February 14, 1995: US05389426 (30 worldwide citation)

A porous material having a top surface and a bottom surface, and a dye applied to the bottom surface of the porous material. The dye is soluble in a volatile imaging liquid contained in a suitable marker, such that when the volatile liquid contacts the top surface of the porous media, the volatile l ...


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Robert P Arens: Thermally-activated time-temperature indicator. Minnesota Mining and Manufacturing Co, Donald M Sell, James A Smith, Richard E Brink, January 31, 1984: US04428321 (29 worldwide citation)

Device which visually indicates exposure to a temperature within a predetermined range for a predetermined length of time. An opaque microporous sheet has a colored stratum on the back and a transparent fusible coating on the face. The coating is a solid solution of amorphous rubbery polymer in crys ...


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Robert P Arens: Demand and timed renewing imaging media. Minnesota Mining and Manufacturing Company, Cruzan Alexander, Donald M Sell, Richard E Brink, November 10, 1981: US04299880 (29 worldwide citation)

Microvoid-containing sheet material of the type which displays visible indicia when a liquid applied to the surface fills the microvoids. The improvement lies in making the liquid-receiving surface from particles held in pseudo-sintered juxtaposition by a thermoset binder, thereby rendering the stru ...


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Robert P Arens: Oil-repellent microvoid-imaging material. Minnesota Mining and Manufacturing Company, Cruzan Alexander, Donald M Sell, Richard E Brink, February 22, 1983: US04374889 (28 worldwide citation)

Re-usable sheet material, having a dark colored base sheet provided on each side with a microvoid layer, temporarily imageable by application of volatile liquids, is treated on the face side with oleophobic (preferably also hydrophobic) fluorochemicals. Surface contamination of the face side with oi ...


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Robert P Arens: Imaging device. Minnesota Mining and Manufacturing Company, Donald M Sell, James A Smith, Richard E Brink, March 8, 1988: US04729687 (21 worldwide citation)

Improved imaging device for applying temporary indicia to substrate of the type having a base covered with a relatively light color, opaque, open cell microvoid-containing layer that is rendered translucent when the microvoids are filled with a liquid having a refractive index similar to that of the ...


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Robert P Arens: Article capable of displaying defined images. Minnesota Mining and Manufacturing Company, Gary L Griswold, Walter N Kirn, James V Lilly, October 11, 1994: US05354598 (19 worldwide citation)

An article capable of being marked by application of a colored or non-colored fluid thus creating a visible image thereon, said article comprising a substrate bearing a patterned or discontinuous barrier to said fluid.


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