Ronald R Kovalak

6548560, Apr 15, 2003

Mar 29, 2000

09/537541

Ronald Roy Kovalak - Canal Fulton OH
Lawrence Keith Hunt - Hudson OH

The Goodyear Tire Rubber Company - Akron OH

C08J 1110

521 41, 521 44

This invention is based upon the unexpected discovery that cured rubber can be devulcanized by heating it to a temperature of at least about 150Â C. under a pressure of at least about 3. 4Ã10 Pascals in the presence of a solvent selected from the group consisting of alcohols and ketones having a critical temperature within the range of about 200Â C. to about 350Â C. The molecular weight of the rubber can be maintained at a relatively high level if the devulcanization is carried out at a temperature of no more than about 300Â C. This devulcanization technique does not significantly change the microstructure of the rubber. In other words, the devulcanized rubber can be recompounded and recured into useful articles in substantially the same way as was the original rubber. This invention more specifically discloses a process for devulcanizing cured rubber into devulcanized rubber that is capable of being recompounded and recured into useful rubber products, said process comprising (1) heating the cured rubber to a temperature which is within the range of about 150Â C. to about 300Â C.

58919260, Apr 6, 1999

Mar 12, 1998

/041558

Lawrence Keith Hunt - Hudson OH
Ronald Roy Kovalak - Canal Fulton OH

The Goodyear Tire & Rubber Company - Akron OH

C08J 1104

521 41

This invention is based upon the unexpected discovery that cured rubber can be devulcanized by heating it to a temperature of at least about 150. degree. C. under a pressure of at least about 3. 4. times. 10. sup. 6 Pascals in the presence of 2-butanol. The molecular weight of the rubber can be maintained at a relatively high level if the devulcanization is carried out in the presence of the 2-butanol at a temperature of no more than about 300. degree. C. This devulcanization technique does not significantly change the microstructure of the rubber and it can accordingly be used in the same types of applications as was the original rubber. In other words, the devulcanized rubber can be recompounded and recurred into useful articles in substantially the same way as was the original rubber. This invention more specifically discloses a process for devulcanizing cured rubber into devulcanized rubber that is capable of being recompounded and recurred into useful rubber products, said process comprising (1) heating the cured rubber to a temperature which is within the range of about 150. degree. C. to about 300. degree. C.

61645710, Dec 26, 2000

Aug 30, 1999

9/385323

Ronald Roy Kovalak - Canal Fulton OH
Lawrence Keith Hunt - Hudson OH

The Goodyear Tire & rubber Company

B02C 1912

241 16

This invention is based upon the unexpected discovery that the crosslinks in thermoset plastics can be broken by heating to a temperature of at least about 150. degree. C. under a pressure of at least about 3. 4. times. 10. sup. 6 Pascals in the presence of 2-butanol. By utilizing the process of this invention, precious metals can be easily and economically recovered from electronic circuit boards. In this process, the crosslinks in the thermoset plastics in the circuit board break under conditions of heat and pressure in the presence of 2-butanol. After the crosslinks in the thermoset plastic break, the plastic material dissolves in the 2-butanol and can be removed by decanting. The remaining undissolved fiberglass mat and precious metal is removed by filtration, decanting or centrifugation. The precious metals which were entrapped in the thermoset plastic can be recovered from fiberglass on the circuit board by being melted. This invention more specifically discloses a process for recovering a precious metal which is entrapped in a thermoset plastic which comprises the steps of (1) heating the precious metal which is entrapped in the thermoset plastic to a temperature which is within the range of about 150. degree. C.