Process for preparing electroconductive coatings

Abstract

An aqueous dispersion of latex particles, said latex particles containing a polymer containing monomer units according to formula (I): in which R 1 and R 2 independently of one another represent hydrogen or a C 1-5 -alkyl group or together form an optionally substituted C 1-5 -alkylene residue and at least one polyanion compound, said latex having a primary particle size of less than 40 nm and said dispersion contains an organic compound containing a di- or polyhydroxy- and/or carboxy groups or amide or lactam group or an aprotic compound with a dielectric constant, ε, ≧15, wherein said latex particles contain said at least one polyanion compound and said polymer in a weight ratio of at least 4; a process for preparing an electroconductive coating comprising the steps of: preparing an aqueous solution or dispersion of the above-mentioned polymer by polymerization with an initiator in a reaction medium in the presence of at least one polyanion compound under oxidizing or reducing conditions, wherein the weight ratio of the at least one polyanion compound to said structural units during the reaction is in the range of 4:1 to 20:1; preparing a first coating composition containing said polymer associated with said at least one polyanion compound and an organic compound containing a di- or polyhydroxy- and/or carboxy groups or amide or lactam group in a aqueous or non-aqueous medium; coating said first coating composition on an object thereby producing a first layer; and heating said first layer at a temperature of at least 100° C.; and a process for preparing an electroconductive coating comprising the steps of: preparing an aqueous solution or dispersion of the above-mentioned polymer by polymerization with an initiator in a reaction medium in the presence of at least one polyanion compound under oxidizing or reducing conditions, wherein the weight ratio of said at least one polyanion compound to said structural units during the reaction is in the range of 4:1 to 20:1; preparing a second coating composition containing said polymer associated with said at least one polyanion compound and an aprotic compound with a dielectric constant, ε, ≧15 in an aqueous or non-aqueous medium; coating said second coating composition on an object thereby producing a second layer; and heating said second layer at a temperature of at least 50° C.

We claim:  
     
         1 . An aqueous dispersion of latex particles, said latex particles containing a polymer consisting of structural units including 5 monomer units according to formula (I):  
       
         
           
           
               
               
           
         
       
       in which R 1  and R 2  independently of one another represent hydrogen or a C 1-5 -alkyl group or together form an optionally substituted C 1-5 -alkylene residue and at least one polyanion compound, said latex having a primary particle size of less than 40 nm and said dispersion contains an organic compound containing a di- or polyhydroxy- and/or carboxy groups or amide or lactam group or an aprotic compound with a dielectric constant, ε, ≧15, wherein said latex particles contain said at least one polyanion compound and said polymer in a weight ratio of at least 4.  
     
     
         2 . Aqueous dispersion of a latex according to  claim 1 , wherein the 20 weight ratio of said at least one polyanion compound to said polymer corresponds to the weight ratio of the monomer(s) constituting said polymer to said at least one polyanion compound during the preparation thereof.  
     
     
         3 . Aqueous dispersion of a latex according to  claim 1 , wherein said latex particles contain said at least one polyanion compound and said polymer in a weight ratio of greater than 4 and less than 20.  
     
     
         4 . Aqueous dispersion of a latex according to  claim 1 , wherein said latex is prepared in a reaction medium with less than 8500 mg of oxygen/L of said reaction medium when the initiator is added.  
     
     
         5 . Aqueous dispersion of a latex according to  claim 1 , wherein said 35 latex is prepared in a reaction medium with less than 2000 mg of oxygen/L of said reaction medium when the initiator is added.  
     
     
         6 . Aqueous dispersion of a latex according to  claim 1 , wherein said latex is prepared in a reaction medium with less than 1000 mg of oxygen/L of said reaction medium when the initiator is added.  
     
     
         7 . Aqueous dispersion of a latex according to  claim 1 , wherein said monomer units according to formula (I) are selected from the group consisting of optionally alkyl group-substituted 3,4-methylenedioxy-thiophene units, optionally alkyl or aryl-group-substituted 3,4-ethylenedioxythiophene units, optionally alkyl or aryl-group-substituted 3,4-ethylenedioxythiophene units, a unit according to formula (I) in which R 1  and R 2  are together a 1,2-cyclohexene group, optionally alkyl or aryl-group-substituted 3,4-propylenedioxythiophene units, optionally alkyl or aryl-group-substituted 3,4-butylenedioxythiophene units and optionally alkyl or aryl-group-substituted 3,4-pentylenedioxythiophene units.  
     
     
         8 . Aqueous dispersion of a latex according to  claim 1 , wherein said polymer is a copolymer of a 3,4-alkylenedioxythiophene compound with a solubility in water at 25° C. of less than 2.2 g/L with a 3,4-alkylenedioxythiophene compound with a solubility in water at 25° C. of at least 2.2 g/L.  
     
     
         9 . Aqueous dispersion of a latex according to  claim 8 , wherein said 3,4-alkylenedioxythiophene compound with a solubility in water at 25° C. of at least 2.2 g/L is selected from the group consisting of: 3,4-dihydro-2H-thieno[3,4-b][1,4]dioxin-2-yl)methanol, 3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepin-3-ol, (2,3-dihydro-thieno[3,4-b][1,4]dioxin-2-yl-methoxy)-acetic acid ethyl ester, (2,3-dihydro-thieno[3,4-b][1,4]dioxin-2-yl-methoxy)-acetic acid, 2-{2-[2-(2-methoxy-ethoxy)-ethoxy]-ethoxymethyl}-2,3-dihydro-thieno[3,4-b][14]dioxine and 4-(2,3-dihydro-thieno[3,4-b][1,4]dioxin-2-ylmethoxy)-butane-1-sulfonic acid sodium salt.  
     
     
         10 . Aqueous dispersion of a latex according to  claim 1 , wherein said at least one polyanion compound includes poly(styrene sulphonic acid).  
     
     
         11 . A process for preparing an electroconductive coating comprising the steps of: preparing an aqueous solution or dispersion of a polymer consisting of structural units including monomer units according to formula (I):  
       
         
           
           
               
               
           
         
       
       by polymerization with an initiator in a reaction medium in the presence of at least one polyanion compound under oxidizing or reducing conditions, wherein the weight ratio of said at least one polyanion compound to said structural units during the reaction is in the range of 4:1 to 20:1; preparing a first coating composition containing said polymer associated with said at least one polyanion compound and an organic compound containing a di- or polyhydroxy- and/or carboxy groups or amide or lactam group in a aqueous or non-aqueous medium; coating said first coating composition on an object thereby producing a first layer; and heating said first layer at a temperature of at least 100° C.  
     
     
         12 . Process according to  claim 11 , wherein when said preparation is carried out under an inert atmosphere such that when said initiator is added less than 850 mg of oxygen per litre of the reaction medium is present in the reaction medium.  
     
     
         13 . Process according to  claim 11 , wherein when said initiator is added less than 200 mg of oxygen per litre of said reaction medium is present in said reaction medium.  
     
     
         14 . Process according to claim ll wherein when said initiator is added less than 100 mg of oxygen per litre of said reaction medium is present in said reaction medium.  
     
     
         15 . Process according to  claim 11 , wherein said monomer units according to formula (I) are selected from the group consisting of optionally alkyl group-substituted 3,4-methylenedioxy-thiophene units, optionally alkyl or aryl-group-substituted 3,4-ethylenedioxythiophene units, optionally alkyl or aryl-group-substituted 3,4-ethylenedioxythiophene units, a unit according to formula (I) in which R 1  and R 2  are together a 1,2-cyclohexene group, optionally alkyl or aryl-group-substituted 3,4-propylenedioxythiophene units, optionally alkyl or aryl-group-substituted 3,4-butylenedioxythiophene units and optionally alkyl or aryl-group-substituted 3,4-pentylenedioxythiophene units.  
     
     
         16 . Process according to  claim 11 , wherein said polymer is a copolymer of a 3,4-alkylenedioxythiophene compound with a solubility in water at 25° C. of less than 2.2 g/L with a 3,4-alkylenedioxythiophene compound with a solubility in water at 25° C. of at least 2.2 g/L.  
     
     
         17 . Process according to  claim 16 , wherein said 3,4-alkylenedioxythiophene compound with a solubility in water at 25° C. of at least 2.2 g/L is selected from the group consisting of: 3,4-dihydro-2H-thieno[3,4-b][1,4]dioxin-2-yl)methanol, 3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepin-3-ol, (2,3-dihydro-thieno[3,4-b][1,4]dioxin-2-yl-methoxy)-acetic acid ethyl ester, (2,3-dihydro-thieno[3,4-b][1,4]dioxin-2-yl-methoxy)-acetic acid, 2-{2-[2-(2-methoxy-ethoxy)-ethoxy]-ethoxymethyl}-2,3-dihydro-thieno[3,4-b][14]dioxine and 4-(2,3-dihydro-thieno[3,4-b][1,4]dioxin-2-ylmethoxy)-butane-1-sulfonic acid sodium salt.  
     
     
         18 . Process according to  claim 11 , wherein said at least one polyanion compound includes poly(styrene sulphonic acid).  
     
     
         19 . A process for preparing an electroconductive coating comprising the steps of: preparing an aqueous solution or dispersion of a polymer consisting of structural units including monomer units according to formula (I):  
       
         
           
           
               
               
           
         
       
       by polymerization with an initiator in a reaction medium in the presence of at least one polyanion compound under oxidizing or reducing conditions, wherein the weight ratio of said at least one polyanion compound to said structural units during the reaction is in the range of 4:1 to 20:1; preparing a second coating composition containing said polymer associated with said at least one polyanion compound and an aprotic compound with a dielectric constant, ε, ≧15 in an aqueous or non-aqueous medium; coating said second coating composition on an object thereby producing a second layer; and heating said second layer at a temperature of at least 50° C.  
     
     
         20 . Process according to  claim 19 , wherein when said preparation is carried out under an inert atmosphere such that when said initiator is added less than 850 mg of oxygen per litre of the reaction medium is present in the reaction medium.  
     
     
         21 . Process according to  claim 19 , wherein when said initiator is added less than 200 mg of oxygen per litre of said reaction medium is present in said reaction medium.  
     
     
         22 . Process according to  claim 19 , wherein when said initiator is added less than 100 mg of oxygen per litre of said reaction medium is present in said reaction medium.  
     
     
         23 . Process according to  claim 19 , wherein said monomer units according to formula (I) are selected from the group consisting of optionally alkyl group-substituted 3,4-methylenedioxy-thiophene units, optionally alkyl or aryl-group-substituted 3,4-ethylenedioxythiophene units, optionally alkyl or aryl-group-substituted 3,4-ethylenedioxythiophene units, a unit according to formula (I) in which R and R are together a 1,2-cyclohexene group, optionally alkyl or aryl-group-substituted 3,4-propylenedioxythiophene units, optionally alkyl or aryl-group-substituted 3,4-butylenedioxythiophene units and optionally alkyl or aryl-group-substituted 3,4-pentylenedioxythiophene units.  
     
     
         24 . Process according to  claim 19 , wherein said polymer is a copolymer of a 3,4-alkylenedioxythiophene compound with a solubility in water at 25° C. of less than 2.2 g/L with a 3,4-alkylenedioxythiophene compound with a solubility in water at 25° C. of at least 2.2 g/L.  
     
     
         25 . Process according to  claim 24 , wherein said 3,4-alkylenedioxythiophene compound with a solubility in water at 25° C. of at least 2.2 g/L is selected from the group consisting of: 3,4-dihydro-2H-thieno[3,4-b][1,4]dioxin-2-yl)methanol, 3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepin-3-ol, (2,3-dihydro-thieno[3,4-b][1,4]dioxin-2-yl-methoxy)-acetic acid ethyl ester, (2,3-dihydro-thieno[3,4-b][1,4]dioxin-2-yl-methoxy)-acetic acid, 2-{2-[2-(2-methoxy-ethoxy)-ethoxy]-ethoxymethyl}-2,3-dihydro-thieno[3,4-b][14]dioxine and 4-(2,3-dihydro-thieno[3,4-b][1,4]dioxin-2-ylmethoxy)-butane-1-sulfonic acid sodium salt.  
     
     
         26 . Process according to  claim 19 , wherein said at least one polyanion compound includes poly(styrene sulphonic acid).