Imaging particulates, paper and process, and imaging of paper using dual wavelength light

Abstract

The present invention provides dual wavelength imaging compositions, processes for forming dual wavelength imaging compositions, methods for forming images using dual wavelength imaging compositions and substrate (e.g., paper web) treated (e.g., coated) on one or both sides with dual wavelength imaging compositions. Also provided is a dual wavelength imaging particulate comprising a matrix of polymer material and containing: one or more image-forming agents; a photo-oxidizing agent which is activated at a first wavelength of light to cause the one or more image-forming agents to form one or more images; and a reducing agent which is activated at a second wavelength of light to cause termination of the formation of the one or more images.

What is claimed is: 
     
         1 . An article comprising: a dual wavelength image-forming particulate comprising a matrix of polymer material and containing: one or more image-forming agents; a photo-oxidizing agent which is activated at a first wavelength of light to cause the one or more image-forming agents to form one or more images; and a reducing agent which is activated at a second wavelength of light to cause termination of the formation of the one or more images. 
     
     
         2 . The article of  claim 1 , wherein the polymer material comprises cellulose acetate butyrate. 
     
     
         3 . The article of  claim 1 , wherein the imaging agents comprise a leuco dye. 
     
     
         4 . The article of  claim 1 , wherein the matrix of each particulate further comprises a plasticizer. 
     
     
         5 . The article of  claim 1 , wherein the photo-oxidizing agent is activated at a wavelength in the range of from about 300 to about 350 nm, and wherein the reducing agent is activated at a wavelength in the range of from about 360 to about 450 nm. 
     
     
         6 . The article of  claim 1 , wherein at least some of the particulates are about 10 microns or less in diameter. 
     
     
         7 . The article of  claim 6 , wherein at least some of the particulates are about 5 microns or less in diameter. 
     
     
         8 . An imaging composition comprising:
 a solvent; and   a plurality of dual wavelength image-forming particulates dispersed in the solvent, wherein each particulate of the plurality of particulates comprises a matrix of polymer material and contains:
 one or more imaging agents; and 
 a photo-oxidizing agent which is activated at a first wavelength of light to cause the one or more image-forming agents to form one or more images; and 
 a reducing agent which is activated at a second wavelength of light to cause termination of the formation of the one or more images. 
   
     
     
         9 . The imaging composition of  claim 8 , wherein the solvent comprises water. 
     
     
         10 . The imaging composition of  claim 8 , wherein the polymer material comprises cellulose acetate butyrate. 
     
     
         11 . The imaging composition of  claim 8 , wherein the polymer material comprises from about 40 to about 99% of the solids portion of the imaging composition. 
     
     
         12 . The imaging composition of  claim 11 , wherein the polymer material comprises from about 50 to about 80% of the solids portion of the imaging composition. 
     
     
         13 . The imaging composition of  claim 8 , wherein the matrix of each particulate further comprises a plasticizer and wherein the plasticizer comprises up to about 45% of the solids portion of the imaging composition. 
     
     
         14 . The imaging composition of  claim 13 , wherein the plasticizer comprises from about 10 to about 20% of the solids portion of the imaging composition. 
     
     
         15 . The imaging composition of  claim 8 , wherein the one or more imaging agents comprises a leuco dye comprising from about 0.1 to about 10% of the solids portion of the imaging composition. 
     
     
         16 . The imaging composition of  claim 15 , wherein the leuco dye comprises from about 1 to about 3% of the solids portion of the imaging composition. 
     
     
         17 . The imaging composition of  claim 8 , wherein each particulate further contains one or more acids/couplers and wherein the acids/couplers collectively comprise from about 0.1 to about 20% of the solids portion of the imaging composition. 
     
     
         18 . The imaging composition of  claim 17 , wherein the acids/couplers collectively comprise from about 1 to about 6 of the solids portion of the imaging composition. 
     
     
         19 . The imaging composition of  claim 8 , wherein the photo-oxidizing agent is activated at a wavelength in the range of from about 300 to about 350 nm, and wherein the reducing agent is activated at a wavelength in the range of from about 360 to about 450 nm. 
     
     
         20 . The imaging composition of  claim 8 , wherein the particulates are about 10 microns or less in diameter. 
     
     
         21 . The imaging composition of  claim 20 , wherein at least some of the particulates are about 5 microns or less in diameter. 
     
     
         22 . An article comprising:
 a substrate having first and second surfaces; and   a plurality of image-forming particulates applied to at least one of the first and second surfaces, each particulate comprising a matrix of polymer material and containing:
 one or more imaging agents; 
 a photo-oxidizing agent which is activated at a first wavelength of light to cause the one or more image-forming agents to form one or more images in or on the substrate; and 
 a reducing agent which is activated at a second wavelength of light to cause termination of the formation of the one or more images. 
   
     
     
         23 . The article of  claim 22 , wherein the polymer material comprises cellulose acetate butyrate. 
     
     
         24 . The article of  claim 22 , wherein the polymer material comprises from about 40 to about 99% of the solids portion of the imaging composition. 
     
     
         25 . The article of  claim 24 , wherein the polymer material comprises from about 50 to about 80% of the solids portion of the imaging composition. 
     
     
         26 . The article of  claim 22 , wherein the matrix of each particulate further comprises a plasticizer and wherein the plasticizer comprises up to about 45% of the solids portion of the imaging composition. 
     
     
         27 . The article of  claim 26 , wherein the plasticizer comprises from about 10 to about 20% of the solids portion of the imaging composition. 
     
     
         28 . The article of  claim 22 , wherein the one or more imaging agents comprise a leuco dye comprising from about 0.1 to about 10% of the solids portion of the imaging composition. 
     
     
         29 . The article of  claim 28 , wherein the leuco dye comprises from about 1 to about 3% of the solids portion of the imaging composition. 
     
     
         30 . The article of  claim 22 , wherein each particulate further contains one or more acids/couplers and wherein the acids/couplers collectively comprise from about 0.1 to about 20% of the solids portion of the imaging composition. 
     
     
         31 . The article of  claim 30 , wherein the acids/couplers collectively comprise from about 1 to about 6 of the solids portion of the imaging composition. 
     
     
         32 . The article of  claim 22 , wherein the photo-oxidizing agent is activated at a wavelength in the range of from about 300 to about 450 nm. 
     
     
         33 . The article of  claim 22 , wherein the photo-oxidizing agent is activated at a wavelength in the range of from about 300 to about 350 nm, and wherein the reducing agent is activated at a wavelength in the range of from about 360 to about 450 nm. 
     
     
         34 . The article of  claim 22 , wherein at least some of the particulates are about 10 microns or less in diameter. 
     
     
         35 . The article of  claim 34 , wherein at least some of the particulates are about 5 microns or less in diameter. 
     
     
         36 . A process comprising the following steps:
 (a) providing a substrate having first and second surfaces; and   (b) providing a plurality of dual wavelength imaging particulates, wherein the particulates each comprise a matrix of polymer material and contain:
 one or more imaging agents; 
 a photo-oxidizing agent which is activated at a first wavelength of light to cause the one or more image-forming agents to form one or more images in or on the substrate; and 
 a reducing agent which is activated at a second wavelength of light to cause termination of the formation of the one or more images; 
   (c) treating at least one of the first and second surfaces of the substrate of step (a) with the particulates of step (b).   
     
     
         37 . The process of  claim 36 , wherein the substrate of step (a) comprises a paper web and wherein step (b) is carried out with a metering size press to treat at least one surface of the paper web with the particulates of step (b). 
     
     
         38 . The process of  claim 36 , wherein the polymer material of each particulate of step (b) comprises cellulose acetate butyrate. 
     
     
         39 . The process of  claim 36 , wherein the one or more imaging agents of step (b) comprise a leuco dye. 
     
     
         40 . The process of  claim 36 , wherein each particulate of step (b) further contains one or more acids/couplers. 
     
     
         41 . The process of  claim 36 , wherein the photo-oxidizing agent of step (b) is activated at a wavelength in the range of from about 300 to about 350 nm, and wherein the reducing agent of step (b) is activated at a wavelength in the range of from about 360 to about 450 nm. 
     
     
         42 . The method comprising the following steps:
 (a) providing a dual wavelength imaging substrate comprising:
 a substrate having a first surface and a second surface; and 
 a plurality of dual wavelength image-forming particulates applied to at least one of the first and second surfaces, wherein the particulates each comprise a matrix of polymer material and contain: 
 one or more imaging agents; 
 a photo-oxidizing agent which is activated at a first wavelength of light to cause the one or more image-forming agents to form one or more images; and 
 a reducing agent which is activated at a second wavelength of light to cause termination of the formation of the one or more images; 
   (b) subjecting the dual wavelength imaging substrate of step (a) to the first wave length of light that activates the photo-oxidizing agent to cause the one or more imaging agents to form one or more images in or on the substrate; and   (c) subjecting the imaged substrate of step (b) to the second wave length of light that activates the reducing agent to cause the termination of the formation of the one or more images.   
     
     
         43 . The method of  claim 42 , wherein the polymer material of each particulate of step (a) comprises cellulose acetate butyrate. 
     
     
         44 . The method of  claim 42 , wherein the one or more imaging agents of step (a) comprise a leuco dye. 
     
     
         45 . The method of  claim 42 , wherein the photo-oxidizing agent of step (a) is activated during step (b) at a wavelength in the range of from about 300 to about 350 nm, and wherein the reducing agent of step (a) is activated during step (c) at a wavelength in the range of from about 360 to about 450 nm. 
     
     
         46 . A process for making a dual wavelength imaging composition comprising the following steps:
 (a) providing a solvent; and   (b) dispersing a plurality of dual wavelength image-forming particulates in the solvent to form a dual wavelength imaging composition, wherein each particulate of the plurality of particulates comprises a matrix of polymer material and contains:
 one or more image-forming agents; a photo-oxidizing agent which is activated at a first wavelength of light to cause the one or more image-forming agents to form one or more images; and 
 a reducing agent which is activated at a second wavelength of light to cause termination of the formation of the one or more images. 
   
     
     
         47 . The process of  claim 46 , wherein the solvent of step (a) comprises water. 
     
     
         48 . The process of  claim 46 , wherein the polymer material of each particulate of step (b) comprises cellulose acetate butyrate. 
     
     
         49 . The process of  claim 46 , wherein the polymer material comprises from about 40 to about 99% of the solids portion of the imaging composition of step (b). 
     
     
         50 . The process of  claim 46 , wherein the one or more imaging agents of step (b) comprise a leuco dye comprising from about 0.1 to about 10% of the solids portion of the imaging composition. 
     
     
         51 . The process of  claim 46 , wherein at least some of the particulates of step (b) are about 10 microns or less in diameter. 
     
     
         52 . The process of  claim 51 , wherein at least some of the particulates of step (b) are about 5 microns or less in diameter. 
     
     
         53 . The process of  claim 46 , wherein the particulates of step (b) are formed by the steps of: (c) coarsely grinding solid polymer material to form coarsely ground particulates; (d) dispersing the coarsely ground particulates in starch in water mixture to form a slurry; and (e) wet slurry grinding the dispersed particulates to provide the particulates of step (b). 
     
     
         54 . The process of  claim 46 , wherein the particulates of step (b) are formed by the steps of:
 (c) coarsely grinding solid polymer material to form coarsely ground particulates; and (d) cryogenically grinding the coarsely ground particulates.