US2005161843A1PendingUtilityA1

Process of producing microcapsules and product thereof

42
Priority: Jan 23, 2004Filed: Jan 23, 2004Published: Jul 28, 2005
Est. expiryJan 23, 2024(expired)· nominal 20-yr term from priority
Inventors:Yongcai WangPaul M. HoderleinDennis E. SmithPeter Rochester
B01J 13/04G03F 7/002
42
PatentIndex Score
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Cited by
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Claims

Abstract

This invention relates to a process for preparing microcapsules containing a hydrophobic liquid core material, the process comprising: (1) mixing an organic liquid phase which comprises the hydrophobic liquid core material with an aqueous phase comprising a stabilizer to form a premix; (2) homogenizing the premix by forcing the premix under pressure through a high pressure passage into a low pressure area to produce a microparticle dispersion, said microparticles having a mean size of greater than 1.0 micron, (3) adding an encapsulating material prior to step (4); and (4) curing the encapsulating material associated with the microparticles to form the microcapsules.

Claims

exact text as granted — not AI-modified
1 . A process for preparing microcapsules containing a hydrophobic liquid core material, the process comprising: 
 (1) mixing an organic liquid phase which comprises the hydrophobic liquid core material with an aqueous phase comprising a stabilizer to form a premix;    (2) homogenizing the premix by forcing the premix under pressure through a high pressure passage into a low pressure area to produce a microparticle dispersion, said microparticles having a mean size of greater than 1.0 micron,    (3) adding an encapsulating material at any time prior to step (4); and    (4) curing the encapsulating material associated with the microparticles to form the microcapsules.    
     
     
         2 . The process of  claim 1  wherein the microparticles have a mean size of greater than 2.0 microns.  
     
     
         3 . The process of  claim 2  wherein the microparticles have a mean size of greater than 2.0 and less than 50 microns.  
     
     
         4 . The process of  claim 2  wherein the microparticles have a mean size of greater than 2.0 and less than 20 microns.  
     
     
         5 . The process of  claim 2  wherein the microparticles have a mean size of greater than 2.0 and less than 15 microns.  
     
     
         6 . The process of  claim 1  wherein the encapsulating material is added only prior to or during step (1).  
     
     
         7 . The process of  claim 1  wherein the encapsulating material is added only after step (2).  
     
     
         8 . The process of  claim 1  wherein the encapsulating material is added prior to or during step (1) and after step (2).  
     
     
         9 . The process of  claim 8  wherein the encapsulating materials added prior to or during step (1) and after step (2) are different.  
     
     
         10 . The process of  claim 1  wherein the pressure differential between the high pressure passage and the low pressure area is greater than 2000 psi.  
     
     
         11  The process of  claim 10  wherein the pressure differential is greater than 4000 psi.  
     
     
         12 . The process of  claim 1  wherein the encapsulation material is cured by heat.  
     
     
         13 . The process of  claim 1  wherein the encapsulation material is cured by a change in pH.  
     
     
         14 . The process of  claim 1  wherein the encapsulation material is cured by a condensation polymerization reaction.  
     
     
         15 . The process of  claim 1  wherein the stabilizer is a polymeric stabilizer.  
     
     
         16 . The process of  claim 1  wherein the stabilizer is a particulate stabilizer.  
     
     
         17 . The process of  claim 16  wherein the particulate stabilizer is a colloidal inorganic oxide.  
     
     
         18 . The process of  claim 16  wherein the particulate stabilizer is a latex.  
     
     
         19 . The process of  claim 1  wherein the stabilizer is a water soluble polymer.  
     
     
         20 . The process of  claim 19  wherein the stabilizer is pectin, sodium polystyrene sulfonate, polyvinyl alcohol, alginate, xanthan gum, poly(vinyl methyl ether), or poly(vinyl pyrrolidone).  
     
     
         21 . The process of  claim 1  wherein the stabilizer is an anionic polymer mixture comprising a mixture of a first sulfonated polystyrene polymer and a second sulfonated polystyrene polymer wherein the ratio of the weight average polymer molecular weight of the first polymer to the second polymer is greater than 2.  
     
     
         22 . The process of  claim 21  wherein the ratio of the weight average polymer molecular weight of the first polymer to the second polymer is greater than 4.  
     
     
         23 . The process of  claim 21  wherein the weight average molecular weight of the first polymer is greater than 500,000.  
     
     
         24 . The process of  claim 21  wherein the weight average molecular weight of the first polymer is greater than 1,000,000.  
     
     
         25 . The process of  claim 1  wherein the stabilizer is other than pectin and further comprises pectin.  
     
     
         26 . The process of  claim 1  wherein the microcapsules are photohardenable.  
     
     
         27 . The process of  claim 1  wherein the liquid core material is a color precursor which can react with a developer material to form color.  
     
     
         28 . The process of  claim 1  wherein the encapsulating material is polyurethane, polyurea, polyamide, polyester, polycarbonate, a urea/formaldehyde resin, a melamine resin, polystyrene, a styrene/methacrylate copolymer, or a styrene/acrylate copolymer.  
     
     
         29 . The process of  claim 1  wherein the encapsulating material is polyurethane, polyurea, polyamide, polyester, or polycarbonate.  
     
     
         30 . The process of  claim 1  wherein the encapsulating material is polyurethane or polyurea.  
     
     
         31 . The process of  claim 1  wherein the weight average molecular weight of the second polymer is less than 300,000.  
     
     
         32 . Microcapsules containing a hydrophobic liquid core material made by the process comprising: 
 (1) mixing an organic liquid phase which comprises the hydrophobic liquid core material with an aqueous phase comprising a stabilizer to form a premix;    (2) homogenizing the premix by forcing the premix under pressure through a high pressure passage into a low pressure area to produce a microparticle dispersion, said microparticles having a mean size of greater than 1.0 micron,    (3) adding an encapsulating material at any time prior to step (4); and    (4) curing the encapsulating material associated with the microparticles to form the microcapsules.    
     
     
         33 . The microcapsules of  claim 32  wherein the microparticles have a mean size of greater than 2.0 microns and less than 20 microns.  
     
     
         34 . An imaging element comprising a support and an image forming unit comprising a developer and microcapsules containing a hydrophobic liquid core material, said microcapsules made by a process comprising: 
 (1) mixing an organic liquid phase which comprises the hydrophobic liquid core material with an aqueous phase comprising a stabilizer to form a premix;    (2) homogenizing the premix by forcing the premix under pressure through a high pressure passage into a low pressure area to produce a microparticle dispersion, said microparticles having a mean size of greater than 1.0 micron,    (3) adding an encapsulating material at any time prior to step (4); and    (4) curing the encapsulating material associated with the microparticles to form the microcapsules.    
     
     
         35 . The imaging element of  claim 34  wherein the imaging element is light sensitive and heat or pressure developable.  
     
     
         36 . The imaging element of  claim 34  wherein the imaging element is light sensitive and pressure developable.  
     
     
         37 . The imaging element of  claim 34  wherein the microcapsules are photohardenable.  
     
     
         38 . The imaging element of  claim 34  wherein the microparticles have a mean size of greater than 2.0 microns.  
     
     
         39 . The imaging element of  claim 34  wherein the microparticles have a mean size of greater than 2.0 and less than 50 microns.  
     
     
         40 . The imaging element of  claim 34  wherein the microparticles have a mean size of greater than 2.0 and less than 20 microns.  
     
     
         41 . The imaging element of  claim 34  wherein the microparticles have a mean size of greater than 2.0 and less than 15 microns.

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