Novel electrophoretic dispersion with a fluorinated solvent and a charge controlling agent

Abstract

The invention relates to a novel electrophoretic dispersion comprising a fluorinated solvent as the continuous phase, charged pigment particles or pigment containing microcapsules as the dispersed phase, and the charge of the pigment particles is provided by a charge controlling agent comprising: (i) a soluble fluorinated electron accepting or proton donating compound or polymer in the continuous phase and an electron donating or proton accepting compound or polymer in the dispersed phase; or (ii) a soluble fluorinated electron donating or proton accepting compound or polymer in the continuous phase and an electron accepting or proton donating compound or polymer in the dispersed phase.

What is claimed is:  
     
         1 . An electrophoretic dispersion comprising a fluorinated solvent as the continuous phase, charged pigment particles or pigment containing microcapsules as the dispersed phase and a charge controlling agent which comprises: 
 (i) a soluble fluorinated electron accepting or proton donating compound or polymer in the continuous phase and an electron donating or proton accepting compound or polymer in the dispersed phase; or    (ii) a soluble fluorinated electron donating or proton accepting compound or polymer in the continuous phase and an electron accepting or proton donating compound or polymer in the dispersed phase.    
     
     
         2 . The dispersion of  claim 1  wherein said fluorinated solvent has a dielectric constant of 1.7 to 30.  
     
     
         3 . The dispersion of  claim 2  wherein said fluorinated solvent has a dielectric constant of 1.7 to 5.  
     
     
         4 . The dispersion of  claim 1  wherein said fluorinated solvent is a solvent or solvent mixture of perfluoroalkane, perfluorocycloalkane, perfluoroarylalkane, perfluoro-tert-amine, perfluoropolyether, hydrofluoropolyether.  
     
     
         5 . The dispersion of  claim 4  wherein said fluorinated solvent is FC-43 or FC-70.  
     
     
         6 . The dispersion of  claim 5  wherein said fluorinated solvent is a perfluoropolyether or hydrofluoropolyether.  
     
     
         7 . The dispersion of  claim 6  wherein said fluorinated solvent is Ausimont HT-170, HT-200, HT-230, ZT-180, Dupont K-6 or K7.  
     
     
         8 . The dispersion of  claim 1  wherein said fluorinated solvent is a polymer or oligomer having a molecular weight less than 50,000, preferably less than 20,000.  
     
     
         9 . The dispersion of  claim 8  wherein said fluorinated solvent is poly(perfluoropropylene oxide) or poly(chlorotrifluoroethylene).  
     
     
         10 . The dispersion of  claim 1  wherein said electron accepting or proton donating compound or polymer is selected from a group consisting of alkyl, aryl, arylalkyl or alkylaryl carboxylic acids and salts thereof, alkyl, aryl, arylalkyl or alkylaryl sulfonic acids and salts thereof, tetra-alkylammonium and other alkylaryl ammonium salts, pyridinium salts and their alkyl, aryl, alkylaryl or arylalkyl derivatives, sulfonamides, perfluoroamides, alcohols, phenols, salicylic acids and salts thereof, acrylic acid, sulfoethyl methacrylate, styrene sulfonic acid, itaconic acid, maleic acid, hydrogen hexafluorophosphate, hydrogen hexafluoroantimonate, hydrogen tetrafluoroborate, hydrogen hexafluoroarsenate (V) and organometallic compounds or complexes containing an electron deficient metal group.  
     
     
         11 . The dispersion of  claim 10  wherein said electron deficient metal group is tin, zinc, magnesium, copper, aluminum, chromium, titanium, cobalt, or zirconium.  
     
     
         12 . The dispersion of  claim 11  wherein said electron deficient metal group is copper, aluminum, titanium or zirconium.  
     
     
         13 . The dispersion of  claim 12  wherein said electron deficient metal group is zirconium or copper.  
     
     
         14 . The dispersion of  claim 1  wherein said electron accepting or proton donating compound or polymer is a protonated polyvinylpyridine copolymer or quarternium salts thereof.  
     
     
         15 . The dispersion of  claim 1  wherein said electron accepting or proton donating compound or polymer is zirconium (tetraacetoacetate).  
     
     
         16 . The dispersion of  claim 1  wherein said electron donating or proton accepting compound or polymer is selected from a group consisting of amines, pyridines, guanidines, ureas, thioureas, imidazoles, tetraarylborate and the alkyl, aryl, alkylary or arylalkyl derivatives thereof.  
     
     
         17 . The dispersion of  claim 16  wherein said electron donating or proton accepting compound or polymer is a copolymer of 2-vinyl pyridine, 4-vinyl pyridine or 2-N,N-dimethylaminoethyl acrylate or methacrylate with styrene, alkyl acrylates or methacrylates, aryl acrylates or methacrylates.  
     
     
         18 . The dispersion of  claim 17  wherein said electron donating or proton accepting compound or polymer is poly(4-vinylpyridine-co-styrene), poly(4-vinlypyridine-co-methyl methacrylate) or poly(4-vinlypyrid ine-co-butyl methacrylate).  
     
     
         19 . The dispersion of  claim 16  wherein said amine is a tert-amine or tert-aniline.  
     
     
         20 . The dispersion of  claim 1  wherein said fluorinated electron accepting or proton donating compound or polymer is selected from a group consisting of fluorinated alkyl, aryl, alkylaryl or arylalkyl carboxylic acids, fluorinated alkyl, aryl, alkylaryl or arylalkyl sulfonic acids, fluorinated sulfonamides, fluorinated carboxamides, fluorinated alcohols, fluorinated ether alcohols, fluorinated phenols, fluorinated salicylic acids, fluorinated pyridinium salts or quaterium ammonium salts, hydrogen tetrafluoroborate, hydrogen hexafluorophosphate, hydrogen hexafluoroantimonate, hydrogen hexafluoroarsenate (V), fluorinated organometallic compounds or fluorinated complexes containing an electron deficient metal group.  
     
     
         21 . The dispersion of  claim 20  wherein said electron deficient metal group is tin, zinc, magnesium, copper, cobalt, aluminum, chromium, titanium or zirconium.  
     
     
         22 . The dispersion of  claim 20  wherein said electron accepting or proton donating compound or polymer is a metal perfluoroacetoacetonate, a fluorinated quinolinol metal complex or a metal phthalocyanine.  
     
     
         23 . The dispersion of  claim 22  wherein said metal perfluoroacetoacetonate is zirconium or copper perfluoroacetoacetonate.  
     
     
         24 . The dispersion of  claim 22  wherein said fluorinated quinolinol metal complex is fluorinated quinolinol Al complexes.  
     
     
         25 . The dispersion of  claim 22  wherein said metal phthalocyanine is copper, zinc or magnesium phthalocyanine.  
     
     
         26 . The dispersion of  claim 20  wherein said fluorinated electron accepting or proton donating compound or polymer is a perfluorocarboxylic acid.  
     
     
         27 . The dispersion of  claim 26  wherein said fluorinated electron accepting or proton donating compound or polymer is Krytox® 157 FSL, Krytox® 157 FSM or Krytox® 157 FSH.  
     
     
         28 . The dispersion of  claim 1  wherein said fluorinated electron donating or proton accepting compound or polymer is selected from a group consisting of fluorinated amines, fluorinated pyridines, fluorinated alkyl or aryl guanidines, fluorinated ureas, fluorinated thioureas, fluorinated tetraborates and derivatives thereof.  
     
     
         29 . The dispersion of  claim 28  wherein said fluorinated amine is a fluorinated tert-amine or tert-aniline.  
     
     
         30 . The dispersion of  claim 29  wherein said fluorinated amine is a derivative of a perfluoropolyether.  
     
     
         31 . The dispersion of  claim 30  wherein said fluorinated amine is a precondensate of a multifunctional amine and a perfluoropolyether methyl ester or perfluoropolyether isocyanate.  
     
     
         32 . The dispersion of  claim 1  wherein each of the proton acceptor and the fluorinated proton donor of (i) or the proton donor and the fluorinated proton acceptor of (ii) is present in the amount of 0.05 to 30 weight percent of the pigment particles or pigment containing microcapsules.  
     
     
         33 . The dispersion of  claim 32  wherein each of the proton acceptor and the fluorinated proton donor of (i) or the proton donor and the fluorinated proton acceptor of (ii) is present in the amount of 0.5 to 15 weight percent of the pigment particles or pigment containing microcapsules.  
     
     
         34 . The dispersion of  claim 1  wherein said dispersed phase comprises pigment particles microencapsulated or coated with a polymer matrix.  
     
     
         35 . The dispersion of  claim 34  wherein said microencapsulated or coated pigment particles are prepared by interfacial or in-situ polymerization/crosslinking reactions using reactive charge controlling agents.  
     
     
         36 . The dispersion of  claim 35  wherein said reactive charge controlling agent is selected from a group consisting of electron donating or proton accepting or electron accepting or proton donating compounds or polymers, having at least one reactive moiety.  
     
     
         37 . The dispersion of  claim 36  wherein said reactive charge controlling agent contains at least a reactive functional moiety selected from the group consisting of unsaturated double bonds such as vinyls, dienes, acrylates or methacrylates, primary or secondary amines, anilines, ureas, thioureas, alcohols, thiols, isocyanates, thioisocyanates, imines, epoxides, acid anhydrides, acid chlorides and chloroformates.  
     
     
         38 . The dispersion of  claim 34  wherein said microcapsules are prepared by microencapsulation involving in-situ radical polymerization with reactive charge controlling agents having unsaturated double bonds.  
     
     
         39 . The dispersion of  claim 38  wherein said reactive charge controlling agent is 2-vinyl pyridine, 4-vinylpyridine, N,N-dimethylaminoethyl acrylate, methacrylic acid, acrylic acid, styrene sulfonic acid, itaconic acid, maleic acid or their salts, and derivatives and co-polymers thereof.  
     
     
         40 . The dispersion of  claim 34  wherein said microcapsules are prepared by microencapsulation involving in-situ condensation polymerization or crosslinking with reactive charge controlling agents.  
     
     
         41 . The dispersion of  claim 40  wherein said reactive charge controlling agent is triethanolamine, diethanolaniline, 1-[N,N-bis(2-hydroxyethyl)amino]-2-propanol, tris-(2-aminoethyl)amine, N,N-(2-hydroxyethyl)aniline, N,N,N′,N′-tetrakis(2-hydroxypropyl)ethylenediamine, N,N,N′,N′-tetrakis(2-hydroxyethyl)ethylenediamine and their derivatives.  
     
     
         42 . The dispersion of  claim 34  wherein said microcapsules are prepared by microencapsulation involving interfacial polymerization or crosslinking with reactive charge controlling agents.  
     
     
         43 . The dispersion of  claim 42  wherein said reactive charge controlling agent is 4-aminomethylpyridine, 1-(2-aminoethyl) piperazine, 1-(3-aminopropyl) imidazole or sulfonated polyisocyanates or a salt thereof.  
     
     
         44 . The dispersion of  claim 35  wherein said reactive charge controlling agent is a fluorinated reactive electron accepting or proton donating or electron donating or proton accepting compound or polymer having at least one reactive functional moiety selected from a group consisting of thiol, hydroxy, amide, primary and secondary amine or aniline, urea, thiourea, imine, isocyanate, thioisocyanate, epoxide, silane, acid anhydride, acid chloride and chloroformate, and unsaturated double bonds such as vinyls, dienes, acrylates and methacrylates.  
     
     
         45 . The dispersion of  claim 44  wherein said reactive functional moiety is amine, hydroxy, thiol, isocyanate or thioisocyanate.  
     
     
         46 . The dispersion of  claim 44  wherein said reactive charge controlling agent is perfluorinated.  
     
     
         47 . The dispersion of  claim 34  wherein said microcapsules are prepared by microencapsulation involving an interfacial polymerization or crosslinking reaction with reactive charge controlling agents followed by solvent evaporation or an in-situ polymerization or crosslinking reaction in the internal phase to harden the microcapsules.  
     
     
         48 . An electrophoretic display which comprises: 
 (a) a top layer and a bottom layer, at least one of which is transparent,    (b) an array of cells sandwiched between the two layers and the cells are filled with an electrophoretic dispersion, which dispersion comprises a fluorinated solvent as the continuous phase, charged pigment particles as the dispersed phase, and a charge controlling agent which comprises: 
 (i) a soluble fluorinated electron accepting or proton donating compound or polymer in the continuous phase and an electron donating or proton accepting compound or polymer in the dispersed phase; or  
 (ii) a soluble fluorinated electron donating or proton accepting compound or polymer in the continuous phase and an electron accepting or proton donating compound or polymer in the dispersed phase.  
   
     
     
         49 . The electrophoretic display of  claim 47  wherein said cells are prepared from microcups and are individually sealed with a polymeric sealing layer.  
     
     
         50 . The electrophoretic display of  claim 47  wherein said cells are microcapsules.  
     
     
         51 . The electrophoretic display of  claim 47  wherein both the top and bottom layers are electrode plates and said display has the traditional up/down switching mode.  
     
     
         52 . The electrophoretic display of  claim 47  wherein one of the top and bottom layers is an electrode plate and the other is an insulator layer and said display has the in-plane switching mode.  
     
     
         53 . The electrophoretic display of  claim 47  wherein both the top and bottom layers are electrode plates and said display has the dual-switching mode.  
     
     
         54 . The dispersion of  claim 1  wherein said charge controlling agent has said soluble fluorinated electron accepting or proton donating compound or polymer and said electron donating or proton accepting compound or polymer of (i), or said soluble fluorinated electron donating or proton accepting compound or polymer, and said electron accepting or proton donating compound or polymer of (ii) in the same molecule.  
     
     
         55 . The dispersion of  claim 54  wherein the charge controlling agent is a condensate product prepared from perfluoroester and tris(2-aminoethyl)amine, 1-[N,N-bis(2-hydroxyethyl)amino]2-propanol or their derivatives.  
     
     
         56 . The dispersion of  claim 54  wherein said same molecule is covalently linked to the particles in the dispersed phase.  
     
     
         57 . An electrophoretic dispersion comprising a fluorinated solvent as the continuous phase, charged pigment particles or pigment containing microcapsules as the dispersed phase and a charge controlling agent comprising soluble fluorinated donor/acceptor moiety and a complementary acceptor/donor moiety in the same molecule wherein said fluorinated donor/acceptor moiety is compatible with the continuous phase and the complementary acceptor/donor moiety is incompatible with the continuous phase.