High pressure processing indicator

Abstract

A device for indicating exposure to a pressure. The device may include a base layer, a plurality of microcapsules, and a coating, with the microcapsules being disposed between the base layer and the coating. The microcapsules contain a indicator material that can be released once the microcapsules burst. The microcapsules then have a compressive bursting strength that is chosen or designed to be less than a selected pressure (e.g., the pressure being that to which a particular article may be exposed during high pressure processing). Thus, when the device is subjected to a pressure greater than the compressive bursting strength, at least some microcapsules burst, the indicator material is released from the microcapsules, and the release of the indicator material can be detected by observation of the device. The device may be a label that is associated (such as by being affixed) to the article being subjected to pressure (or multiple labels being associated (such as by being affixed) to multiple articles. Alternatively, the device may be associated with an article or articles without being affixed thereto.

What is claimed is: 
     
         1 . An article for indicating exposure to a pressure, the article comprising:
 a base layer, a plurality of microcapsules, and a top layer, the microcapsules being disposed between the base layer and the top layer, the microcapsules containing an indicator material including a UV curable ink and having a compressive bursting strength less than a selected pressure;   whereby when the article is subjected to a pressure greater than the compressive bursting strength, at least some microcapsules burst, the indicator material is released from the microcapsules, and the release of the indicator material is detected by observation of the article.   
     
     
         2 . The article of  claim 1 , wherein at least one of the base layer and the top layer is formed from a material that permits detection of indicator material released from the microcapsules by observation of the article. 
     
     
         3 . The article of  claim 1 , wherein the base layer includes a material chosen from a film and paper. 
     
     
         4 . The article of  claim 3 , wherein the base layer includes a film chosen from polypropylene, biaxially-oriented polypropylene, and polyester. 
     
     
         5 . The article of  claim 1 , wherein the ink can change from a colored ink to a colorless or clear ink when exposed to a temperature equal to or greater than a temperature chosen from 104° F., 120° F., and 150° F. 
     
     
         6 . The article of  claim 1 , wherein the top layer is chosen from a film and a varnish. 
     
     
         7 . The article of  claim 6 , wherein the top layer is UV-curable. 
     
     
         8 . The article of  claim 6 , wherein the top layer is a film and includes polypropylene. 
     
     
         9 . The article of  claim 1 , wherein the compressive bursting strength is equal to or less than a selected pressure to which the article will be subjected. 
     
     
         10 . The article of  claim 1 , further comprising an ink layer. 
     
     
         11 . The article of  claim 10 , wherein the ink layer is disposed between the plurality of microcapsules and the base layer. 
     
     
         12 . The article of  claim 11 , wherein the adhesive layer includes at least one adhesive that is an acrylic adhesive.