Invented by Craig R. Hof, Roy A. Ulin, PY MAH Corp, 3M Co
The PY MAH Corp, 3M Co invention works as followsA solvent (I) is a single substance or a mixture of substances that can be adapted to change from a solid at substantially a predetermined temperatures to a liquid. A solvent (I) is a substance that can be either a single or mixed substance and which is able to change from a solid to a liquid phase at substantially the same temperature as it was when it was formed. An indicator system (II), which is composed of one or more substances other than (I), is described in that the solvent (II), when it is present in a liquid state, can change from a solid state at substantially a predetermined temperature to dissolved in the liquid.
Background for Temperature indicating compositions in matter
The invention relates to the field of temperature-indicating compositions and devices therefor, and in particular, the sub-fields of disposable thermometers and compositions of matter which change characteristics with change in phases for use in disposable thermometers.
For many years the conventional mercury thermometer has been the primary temperature-indicating device which has been used in clinical applications for the measurement of temperature in the human body and other animal bodies, and for the measurement of temperature of gases, liquids, and even solids in commercial and industrial applications. As the observer will quickly see, there are many disadvantages to this type of thermometer due to the poisonous nature of mercury and the construction of the mercury thermometer using fragile glass. For clinical applications that involve humans or other animals, it takes several minutes to get a meaningful temperature reading. Because of its high cost, it is imperative that the mercury thermometer be cleaned after use. Sterilization and sterilization can be costly, both in hospitals, doctors’ offices, at home, or out in the field. In hospital sterilization, there is always the possibility of human error. This can lead to contagious diseases like hepatitis. The mercury thermometer’s fragile nature is a danger, especially when used in children’s hands. Fifth, industrial applications that require the determination of high temperatures in vessels in plants or refineries are more difficult than usual. Because of the extreme temperature difference between the mercury thermometer and the ambient temperature outside, conventional thermometers often have extreme error rates after the withdrawal.
Since many years, people have tried to build a cheap thermometer made of materials or mixtures that would change their appearance at a temperature close to the one to be measured. This was done to avoid the disadvantages of the mercury thermometer. For instance, Ramsden in British Pat. No. No. 3640 (1897), provided a paper, celluloid or metal piece, or any other suitable material, which was (1) coated or (2) formed in a hollow, recess or recess with a substance or mixture of materials which would change its opacity depending on the temperature at which it is intended to use the appliance (see pages 1, lines 24-38 and page 5, lines 23 – 45 of British Patent. No. 3640). Ramsden wanted a substance (see pages 2, lines 9-23) which would change color when heated to a certain temperature. However, he did not specify any. He only listed a few substances, fatty acids in general, that would change from opaque to transparent as the phases changed from solid to liquid (see pages 3, lines 11-18), and so dyes, indicator layers, etc. would be required in the device.
Finklestein described yet another type of thermometer in U.S. Pat. No. 3,521,489 (1970). This type of thermometer indicates temperature by the capillary action of the melted material flowing from a “holding compartment”, into a “flow-inducing receiver element”, such as an absorbent material. No. 3,521,489). The same as in the Geldmacher Patent, however, the temperature indication was achieved by using a variety of thermally responsive chemical substances, each of which undergoes a complete state change at a predetermined temperature, with a corresponding shift from opaque to transparent. The use of any “classical” material that changes from opaque to transparent at the phase-change was evident once more. An indicator dye or material would need to be placed at the bottom of the cavity to make it obvious to the observer how the state of the matter changing at the phase-change. Also see Crites U.S. Patent. No. No.
Weinstein and Sagi, in U.S. Pat. No. No. No. 3,631,720) with a plurality of individual temperature-indicating elements distributed over at least one surface of the carrier sheet in the form of a grid with the elements buried in a corresponding number of cavities (located between the sheet 11 and surfaces 20A and 10A), each element 12 having an opaque layer covering an indicator element 20. The coatings 22 of U.S. Pat. No. No. The disadvantage of U.S. Pat. No. No. U.S. pat. No. 3,631,720 with a \”sandwich\” indicator means 20 in temperature-indicating elements 12 became expensive.
In U.S. Pat. No. 3,946,612 (1976) to Sagi and Weinstein, the specification disclosed the use of a heat conducting carrier having a plurality of spaced cavities with a corresponding plurality of solid solutions each comprising an organic layer of at least two different organic chemicals (ortho-chloronitrobromobenzene and ortho-bromonitrobromobenzene) in varied composition ratios deposited in said cavities that would turn from opaque to clear upon a change in phase from solid to liquid. This organic layer (9 U.S. No. No. No. No. No. 3,665,770). The cavity in FIG. When the cavity of FIG. No. When the U.S. Pat. No. 3,946,612 is heated to a certain temperature, it changes the state of matter from a solid into a liquid, allowing the indicator to permeate the opaque layer and force a dye to penetrate the opaque layer, changing the opaque layer’s color to that of the dye. The construction of the U.S. Pat. presented several problems. No. The device was difficult to produce and expensive. The organic composition could not always be completely transformed from liquid to solid. Nucleation sites would remain in the organic layer 9, and resolidification occurred quickly upon removing the thermometer. The size of the layers made it difficult to see the color change when only a small amount of dye was transferred. Keele, U.S. Pat. contains other examples of “opaque” thermometers. No. No. No. No. 2,928,791; Gignilliat III (colors used with solvents from Table I); U.S. Pat. No. No. 3,430,491; (movement of heat-sensitive liquid upon melting into “absorbent backing” layer with different colors, column 7, lines 54 to 59); Roszkowski U.S. Pat. No. 3,785,336 (methyl sterate); Godsey, Jr., U.S. Pat. No. No. No. No. 3,002,385 No. 3,597,976; Lang, U.S. Pat. No. No. 3,677,088 (“spacer layer” between indicator layer & heat-sensitive material); Pickett U.S. Pat. No. 3,704,985 (ortho-chloronitrobenzene: ortho-bromonitrobenzene heat-sensitive material, but no \”space layer\”); Chadha, U.S. Pat. No. 3,712,141 (\”space layer\”); Pickett, U.S. pat. No. No. 3,765,243 (“self-firing thermometer” with exothermic reactions between heat-sensitive materials and dye); Godsey U.S. Pat. No. No. 3,774,450; (“fangible” layer of spacer to be crushed prior to application); Pickett U.S. Pat. No. 3,826,141; Ayres, U.S. Pat. No. No. No. 3,929,021; Chadha, U.S. Pat. No. 3,956,153; Sagi, U.S. Pat. No. 3,835,990, Keele, U.S. Pat. No. 3,859,856; Sagi et al, U.S. Pat. No. Des. 238,661 (1976); Nollen, U.S. Pat. No. 3,895,523; Chilton, U.S. Pat. No. No. 3,998,098. Pickett, U.S. pat. No. 3,871,232.
The Chadha U.S. Pat. teaches the phenomenon of undercooling that occurs with heat-responsive materials when they pass from liquid to solid. No. No.
Another type of device in another art, and not to be misunderstood with the ‘pure’ thermometer (which is only used for measuring temperature), is the (time-temperature) thermometer or the ?time-temperature? watch that indicates by integrating time and temperature a property (such as the degradation of meat due to high temperatures). Chapman, U.S. Pat. No. No. 2,195,395 describes how to measure the thermal abuse of frozen foods by using a dye in water to determine the pH change. Larsson, U.S. Patent. This was a major breakthrough in this art. No. No. 3,946,611, in which paraformaldehyde 19 is FIG. 2, wherein paraformaldehyde 19 in FIG. The pH of wick 18 is reduced by HCl over time, so the dye and wick become darker (see example 3). A color change is not a sign that the solvent’s phases have changed. Gessler U.S. Patent. No. No. No. No. No. No.
Pickett et al., U.S. Pat. No. 3,810,779.
Japanese Patent Application No. “Japanese Patent Applications No.
Some abbreviated efforts have been made to identify substances that change color when phases change for thermometers. However, none has been able overcome the problems associated with using many different unrelated chemicals, accidental overheating etc. Jennings, in U.S. Pat. No. No. Renbaum’s U.S. Patent is a major advancement in the art. No. No. Renbaum did not seem to have tried to determine a solvent system that would work for the electron donor-acceptor pair. This means that a variety of parts are needed to measure any temperature range, for example, Kluth’s problems. Hammond, U.S. Pat. No. No.
A disposable thermometer that was inexpensive was sought after by the thermometer industry. It would have been easy to construct and would use materials that would change some characteristics but not easily reversible upon withdrawal from the source. It would be possible to provide chemical substances that change color upon changing phases. This would eliminate the need for dyes in indicator layer. A disposable thermometer was also needed to magnify the presence an indicator layer in cases that involved “classical” substances, which changed only from opaque or transparent when changing from liquid to solid phase.
In an unpublished, short note from June 1975 written by a scientist who was not affiliated with the inventors (who was trying to develop a thermometer that could be reversed by using molten thermometer chemical instead of solid thermometer chemical), a curious phenomenon was discovered. He discovered that melting and freezing the mixture of ethyl blue and bromothymol red produced a “very obvious” color change. The color of the chemical changed from red to yellow-orange when it solidified. He thought the reaction was completely reversible. The scientist’s screening tests using dyes and indicators showed that bromophenol purple and bromocresol blue could be substituted as bromothymol. The same structures, without bromine, did not work, such as thymol, cresol, and thymol. Scientists also found suitable structures to replace ethyl-red, including crystal violet, para-rosaniline base and para rosaniline, as well as new fuchsin or basic fuchsin. The memo said that 8-hydroxyquinoline was not a dye, but it did serve as a replacement by allowing bromo compounds to go from solid to liquid in a blue-green color. Scientists reported that they tested the indicator compounds in different solid solvent systems and found that color changes only occurred in aromatic systems like naphthalene (2-ethoxybenzyamide), thymol, and 2-naphthyl. Aliphatic compounds like 2-chloroacetamide or sorbitol didn’t show color changes. The report concluded that imidazole is too basic to show any color change, since the indicators went back to their basic state.
An intercompany sales of thermometers with Pinacyanol Iodide/OCNB – OBNB within claim 1, of this invention, was made by an unincorporated Division of the assignee to Applicants Organon Tecknika B.V. on September 30, 1977 for research purposes. The assignee began selling to the general public in the U.S. shortly after January 1, 1980.
4. “4.Click here to view the patent on Google Patents.