CA2106730A1

CA2106730A1 - Dispersion of electrically conductive particles in a dispersing medium

Info

Publication number: CA2106730A1
Application number: CA002106730A
Authority: CA
Inventors: Aaltje E. Wiersma; Lucia M. A. Van De Steeg
Original assignee: Aaltje E. Wiersma; Lucia M. A. Van De Steeg; Dsm N.V.
Current assignee: Koninklijke DSM NV
Priority date: 1992-09-24
Filing date: 1993-09-22
Publication date: 1994-03-25
Also published as: TW278096B; KR100282096B1; KR940007091A; JPH06231615A; MY108714A; US5415893A; EP0589529A1; MX9305851A

Abstract

A B S T R A C T

The invention relates to a dispersion of electrically conductive particles, comprising a binder and an electrically conductive polymer, and a stabiliser in a dispersing medium. The dispersion according to the invention is characterised in that the particles contain a non-ionic stabiliser. It has been found that the stability of the dispersion according to the invention is very good.
In addition the dispersion according to the invention is extremely suitable for providing objects with a coating in a simple manner. The applied coating has good electrically conductive properties as well as good coating properties.
The applied coating is homogeneously distributed over the coated object. Moreover the applied coating appears to adhere well to the object.

Description

~ 0673Q
WK/mjh/10669 5DISPERSION OF ELECTRICALLY CONDUCTIVE PARTICL~S
IN A DISPERSING MEDIUM

The invention relates to a dispersion of electrically conductive particles, comprising a binder and an electrically conductive polymer in a dispersing medium.
Such a dispersion is known from FR-A-2616790.
The dispersion described herein contains electrically conductive particles in a disper~ing medium. The particles have a core, which contains a binder, and a shell, which contains an electrically conductive polymer. The dispersion of electrically conductive particles is obtained by polymerising monomer~ to an electrically conductive polymer in the pre3ence of a dispersion of binder particies. The binder is a thermoplastic polymer and dop1ng groups are present on the surface of the binder particles yielding a disperqion of electrically conductive particles that has homogeneous propQrties as far as the size and composition of the particles is concerned. The dispersion of electrically conductive particles known from FR-A-2616790 can~be used for example to provide non-conductive objects with an electrically conductive coating.
According to FR-A-2616790 doping groups are ~0 re~uired to be present on the surface of the binder particlQs. Di~pe~rsions of polymers known to be non-doping do not meet this requirement and di~persions of conductive particlQs havin~a core of these~polrmer~ are hence not ~ ; obtainable by~the teaching of~FR-A-2616790. It was found - 3S moraover, that dispersions of~doping polymers in many case~ tend to become~destabili ed when the monomer~that~
has to be polymerlsed;to the electrically conductive polymer or ionic compounds, like the oxidant, required to . .

::

2~-57~Q

induce the polymerisation, and doping agents bringing a high and stable conductivity into the conductive polymer are added to the dispersion. The same unwanted effect was found to occur when the said components, required to obtain a conductive polymer are added to a dispersion of a non-doping polymer, stabilised with an anionic or kationic stabiliser. Also these dispersions become unstable by the addition of ionic compounds like oxidants, serving as polymerisation catalyst or doping agents. It is therefore in many cases not possible to effect the polymerisation of monomers into an electrically conductive polymer in a dispersion of the known binder particles of a doping polymer and virtually never in a dispersion of a non-doping polymer.
Because of this it is not really possible to obtain a dispersion of electrically conductive particles -that contain a binder of a non-doping polymer and an electrically conductive polymer and is also impossible in - ;
many ca es to add ionic compounds to the dispersion of the binder particles during the preparation of the dispersion of electrically conductive particles known from FR-A-2616790 without adversely affecting the stability of the dispersion.
The aim of the present învention is to provide a 25 stable dispersion of electrically conductive particles, -which contain a binder of a doping or a non-doping polymer and an electrically conductive polymer. The dispersion of electrically conductive particles according to the invention is characterised in that the electrically conductive particles contain a non-ionic stabiliser.
It has been found that the dispersion of electrically conductive particles according to the ~ -invention is very stable, even when the dispersion contains ionic compounds. It is possible to add ionic 35 compounds, such as catalysts and doping agents, without : -..... . . . , . -. . . .... ..... . . . .. . .. ., ,.. ,~ .. ... .... . . . . . ... . . .. . . . .. .

, .. , , . ., . . "~ , ., ., ,.. , " , ., ,. .. " .. . , ", .. .... .... , .. , ., . .. ,.. .. .. , ., -. . ... . . . .

21~73~

adversely affecting the stability of the dispersion of binder particles, during the preparation of the dispersion of electrically conductive particles according to the -invention. It is possible to use in the dispersion of electrically conductive particles according to the invention without requirements being imposed on the doping properties of the binder. The invention also provides electrically conductive particles containing a non-doping polymer as a binder, which could not be obtained according to the knvwn process of FR-A-2616790.
The dispersion of electrically conductive particles according to the invention is also suitable for providing objects with a coating in a simple manner. The dispersion can be homogeneously applied to the object in a simple manner and leaving the desired coatin~ after removal of the dispersing medium. The obtained coating has good electrically conductive properties. Moreover the coating appears to have good adhesive properties with respect to a diversity of material~.
The dispersion of electrically conductive particles according to the invention is for example obtained by polymerising monomers into an electrically conductive polymer in the presance of a dispersion of binder particles stabilised with a non-ionic stabiliser. A
non-ionic stabiliser is uncharged under the prevailing conditions. The non-ionic stabiliser can be chose~ within a wide range and may be either physically adsorbed to the binder particles (physically bound) or incorporated in the binder (chemically bound). The ~on-ionic stabiliser is for example chosen from the group comprising alkylamines, alkylamides, (ethoxylated) alkyl alcohols, alkylpyrrolidones, (ethoxylated) alkyl phenols, polyoxyalkyl Qsters, polyoxyalkyI ethers, glycol alkyl ethers, glycerol alkyl ethers, fatty acid esters and (ethoxylated) sorbitan alkylates, (hydroxy-(m)ethyl)cellulose and other cellulose compounds known as 'prutective colloids', polyvinyl alcohols, polyvinyl pyrrolidones and polyacrylamides. It is preferable to use ., ' . .

21~30 polyoxyalkyl ethers because of their high effectivity.
Extremely suitable polyoxyalkyl ethers are for example polyoxyethylene ethers, such as polyethylene glycol, alkoxypolyetheylene glycol, such as methoxypolyethylene glycol and ethylene oxide propylene oxide copolymers. In other cases polyoxyalkyl esters are preferred because of their low toxicity. Helmut Stache and Kurt Kosswig give a ~urvey of non-ionic stabilisers in the Tensid-Taschenbuch, Carl Hanser Verlag Wien, 1990.
Optionally the dispersion of binder particles also contains a minor amount of anionic stabilisers, cationic stabiliser~ and/or stabilisers that contain a non-ionic part as well as an ionic part. Preferably the - -non-ionic part contains at least 10 carbon atoms.
Frequently used anionic stabilisers are ~or example alkyl sulphate~ and alkyl sulphonates, ethoxylated alkyl -sulphates, alkyl sulphonates and alkyl phosphates, ethoxylated alkyl carboxylic acids and alkylphenol carboxylic acids, ethoxylated alkylphenol sulphates and -alkyl phenol sulphonates, sulphosuccinates and salts of carboxylic acid. Frequently used cationic stabilisers are -~ -primary, secondary, tertiary and quaternary ammonium salts, alkylpyridinium salts and acetylated polyamines.
Suitable non-ionic stabilisers usually have a ;~
weight average molecular weight of between 100 and 1,000,000 g/mol, preferably between 500 and 5,000 g/mol. A
polymeric non-ionic stabiliser Quitable for the invention is usually composed of monomeric units containing 1-50 carbon atom~. Preferably this is 1-20 carbon atoms.
Optionally the polymeric non-ionic stabiliser contains several unit~ that contain different numbers of carbon atoms. ~n example of such a stabiliser is an ethylene oxide/propylene oxide copolymer. The non-ionic stabiliser may have been added to the dispersion of binder particles in the usual manner.
Preferably the non-ionic stabiliser is chQmically bound to the binder used. Chemically bound ~ ;

,. . .

,,.. , , , ., .;, .. .. . .. . .. . ... . . . . ... . .

. . . ., .. . . , .. ;:. : ~ . . ~ .. .. , . ~, , .. -, ., , . ... -. .. .

210~30 ~ 5 - AE 7495 stabilisers provide a better stability of the dispersion of binder particles during the described process. This can be efected by incorporating units of the non-ionic stabiliser in the binder by adding the non-ionic stabiliser during the manufacturing of the binder. It is also quite possible to gFaft the non-ionic stabiliser onto already manufactured binder particles. The dispersion of binder particles usually contains between 1 and 50 weight percent non-ionic stabiliser, relative to the total weight of binder and stabiliser. Preferably this is 5-25 weight percent. Dispersions of smaller particles usually require less stabilizer than dispersions of larger particles.
The lower limit is imposed by the requirement that the dispersion is sufficiently stabilized. Amounts of stabilizer, beyond the upper limit can deteriorate the conducting and coating properties of the dispersion.
A nen-doping polymer is preferably used as a binder in the dispersion according to the invention. This has the advantage over the use of doping polymers that a doping process can be dispensed with. Preferably the non-doping polymer has good coating properties. Such a polymer is for example chosen from the group comprising alkyd rasins, polyester resins, amino resins, phenolic resins, polyurethane resins, epoxy resins, acrylate resins, cyclic rubbers, such as polyisoprene,~natural rubber, silicone resins, polyvinyl chlorides, (polyjvinyl esters, polyvinyl acetate, polyolefines, which for example contain units cho~en from the group comprising ethylene, propylene, butadiene and styrene, and hydrocarbon resins, such as (co)polymer~ of cyclopentadiene.
~ he alkyd resinæ that can be used as the binder in the dispersion are for example composed of polyols chosen from the ~roup comprising glycerol, pentaerythritol, ethylene glycol, sorbitol, trimethylolethane, trimathylolpropane, dipentaery~hritol, tripentaerythritol, neopentyl glycol and diethylene glycol, and polycarboxylic acids or derivatives thereof, ', . .,: ' ~106730 AE 7495 for example chosen from the group comprising phthalic anhydride, phthalic acid, isophthalic acid, maleic acid, maleic anhydride, fumaric acid, fumaric anhydride and fatty acids, such as linoleic acid and oleic acid.
Possible preparation methods for the alkyd resins are known to a person skilled in the art and are described for example by H.F. Mark et al. in the Encyclopedia of -Chemical Technology, 1978, vol. 2, pp. 18-50.
Suitable polyester resins are for example -composed of dicarboxylic acid units or derivatives thereof, chosen from the group comprising maleic anhydride, fumaric acid, adipic acid, phthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid and tetrachlorophthalic acid and diol units, for example chosen from the group comprising 1,2-propanol, 1,3-butanol, ethylene glycol, neopentyl glycol, diethylene glycol, bisphenol A and tricyclodecane dimethanol. ~;
Optionally monofunctional and/or trifunctional monomeric units may also be used. Possible preparation methods for the polyester resins are known to a person skilled in the art and are described for example by the Oil and Colour Chemists' Association, Australia in 'Surface coatings, Vol. 1 - Raw materials and their usage', Chapman and Hall Ltd, 1983, pp. 78-87.
Suitable epoxy resins are for example derived from bisphenol A and epichlorohydrin. Epoxidized aliphatic and cycloaliphatic dienes, such a 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate and 4-epoxyethyl-1,2-epoxycyclohexane, may al80 be used.
Pos iblQ preparation methods ~or epoxy resins are known to a person skilled in the art and are described for example in Ullman's Encyclopedia of Industrial Chemistry, 1985, ;
Vol. A9, pp. 547-563.
Suitable polyurethane resins are for example reaction products of isocyanates and polyols. The isocyanates are for example chosen from the group oompri 8i ng 1,6-hexamethylene diisocyanate, ': ", '..

21~3~
_ ~ _ AE 7495 polymethylenepolyphenyl isocyanate, 4,4'-methylenebis(phenyl isocyanate), 1,5-naphthalene diisocyanate, bitolylene diisocyanate, methylene biq(cyclohexyl isocyanate), isophorone diisocyanate, trimethylhexamethylene diisocyanate, m-xylylene diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane and 1,4-bis(isocyanatomethyl)cyclohexane. The polyols are usually chosen from the group comprising polyether polyols and polyester polyols. Possible preparation methods for polyurethane resins are for example described in Kirk Othmer's Encyclopedia of Chemical Technology, l9B2, Vol.
23, pp. 576-608.
A dispersion of a polyurethane reqin can for example be stabilised by applying polyoxyethylene segments 15 to the polyurethane chain, as for example described by -J.W. Rosthauser et al. in Advances in Urethane Science and Technology, 1987, Stanford, Vol. 10, pp. 121-162, and by D. Dieterich in Progress in Organic Coatings, 1981, VolO
9, pp. 291-332. The segments can be composed of modified diol or isocyanate units but it is also possible to apply monohydroxyfunctional polyoxyethylene polyethers directly to the polyurethane chain.
Suitable amino resins a;re for example reaction products of formaldehyde and compounds containing an amino group, such as melamine, benzoguanamine, glycoluril and rea. Amino resins and their preparation methods are for example dQscribed by the Oil and Colour Chemists' Association, Australia, in 'Surface coatings, Vol. 1 - Raw material~ and their usage', Chapman and ~all Ltd, 1983, pp. 87-98.
Suitable phenolic resins are for example -reaction products of a phenol compound and an aldehyde oompound, or derivatives thereof. The phenol compound is for example chosen from the group comprising phenol, o-cre~ol, 2,4-xylenol, bisphenol A, p-phenylphenol and p-tertiary-butylphenol. The aldehyde compound i8 for example formaldehyde. Phenolic r~sins and their preparation .. . . .

21067~0 methods are for example described by the Oil and Colour Chemists' Association, Australia, in 'Surface coatings, Vol. 1 - Raw materials and their usage', Chapman and ~all Ltdl 1983, pp. 99-104.
Suitable ~ilicone resins are for example hydrolysis products of di- or trifunctional chlorosilanes.
To this end the chlorosilanes are for example dissolved in an organic solvent, such as toluene or xylene, and then hydrolysed with waterr Silicone resins can also be prepared by treating alkoxysilanes, such as methoxy-, ethoxy- and/or propoxy-silanes, with a strong acid in an aqueous medium and then causing polymerisation to take place. Silicone resins and their preparation methods are -~-for example described by the Oil and Colour Chemists' ~-Association, Australia, in 'Surface coatings, Vol. 1 - Raw materials and their usage~, Chapman and Hall Ltd, 1983, pp. 134-143.
Suitable acrylate resin3 are for example prepared throu~h homopolymerisation of (meth~acrylate monomers, for example methylmethacrylate, ethylmethacrylate or ethylacrylate, or copolymerisation of these monomers with monomers which can react with them, for example acrylonitrile, methacrylamide, maleic anhydride, aliphatic chains with a terminal acrylate 25 group, methacrylic acid, vinyl acetate or styrene. ;
Acrylate resins and their preparation methods are for example described by the Oil and Colour Chemists' A~sociation, Australia, in 'Surface coatings, Vol. 1 - Raw materials and their usage', Chapman and Hall Ltd, 1983, pp. 144-157.
Optionally a mixture of several of the aforementioned binders is used in the dispersion. It is also possible to use hybrid systems.
The binder in the dispersion is optionally ~;
provided with so-called functional groups. By causing thesQ functional groups to react, for example during the drying of the dispersion, preferably by evaporation of the ., .

. - ' .

:

~ 9 - AE 7495 dispersing medium, the binder can for example be cross-linked or can be adhered to a substrate. These functional groups include for axample an OH, an NH2, an NCO, an epoxy, an N-methylal, a phosphate, a sulphate and/or a carboxylate functionality.
The dispersion of binder particles has a weight average particle size that usually lies between 10 nm and 10 ~m. Preferably this particle size lies between 10 nm and 3 ~m. The solids content of the dispersion of binder particles is usually between 1 and 90 wt.%.
The dispersion of electrically conductive particles according to the invention is prepared in for example the following manner. The monomeric units from which the electrically conductive polymer is composed are added to a dispersion, already stabilised by a non-ionic stabiliser, of binder particles in the dispersing medium.
A polymerisation catalyst is also added. The order in which the different components are added to the dispersion of binder particles i8 not important in the framework of the invention. In the presence of a polymerisation catalyst the monomeric units polymerise to form an electrically conductive polymer. In this process the monomers can for example polymerise in the dispersing medium to form an electrically conductive oligomer or polymer, after which the electricall~ conductive oligomer or polymer - which is relatively poorly soluble in the di~persing medium - precipitates onto the stabilised binder particles~ As a result a di~persion of electrically conductive particles i~ obtained, which contain an 30 electrically conductive polymer that i~ substantially ;
adsorbed to the surface of the binder particles. In addition the dispersion of electrically conductive particles may contain freely present electrically conductive polymer.
The temperature at which t.he dispersion of electrically conductive particles according to the invention i~ prepared i8 usually between -50 and 200~C, ' ~' ~lQ~730 preferablv between -10 and 80C. The preparation time is usually between a few seconds and a few day~, dependent on ~`
the rate at which the polymerisation reaction of the monomeric units to the electrically conductive polymer takes place.
A person skilled in the art selects the polymerisation catalyst which is usually added to the dispersion of binder particle~ for example from the group comprising inorganic acids, for example hydrochloric acid, sulphuric acid, chlorosulphonic acid and nitric acid, Lewis acids, for example compounds containing positive ions of iron, aluminium, tin, titanium, zirconium, chromium, manganese, cobalt, copper, molybdenum, wolfram, ruthenium, nickel, palladium and/or platinum, and a 15 halogen, a sulphate, a nitrate, an arylsulphonate and/or -an acetylacetonate. Other suitable catalysts are for example ozonej diaæonium saltq, organic catalysts, for example benzoquinone and anthraquinone. In certain polymerisation reactions Zie~ler-Natta catalysts and compounds like K2Cr207, K2S208, Na2S2O8, NaBO3, H202, NOBF4, NO2BF4, NO2PF6, NOCl04, NOAsF~, NOPF6 and (NH4)2S208 are also , effective. Examples of effective catalyst~ are FeCl3, FeBr3, FeC13.6H20, CuS04 ~ Fe(NO3)3.9H20, CuCl2.2H20, K3Fe(CN)6, Cu(NO3)2, Fe(BF4)3, Fe(C:LO4).3.gH20, Fe2(SO4)3.5H20, , Fe2(SiF6)3, Cu(ClO4)2, Cu(BF4)2, CuSiF6, RuCl3, MoCl5, WCl6 and (C5H~)2Fe~FeCl4~. Optionally use is made of a mixture of different catalysts. The catalyst or catalyst mixture is u~ually added in a molar ratio relative to the monomer that lie~ between 1:10 and 10:1. Preferably this ratio lie~ between 1:3 and 3:1. Iron(III) compound~, especially iron(III) chloride are particularly preferable aæ
oxidizing catalyst when polypyrrole is prepared. It is preferred to add also doping compoundQ th~t give higher conductivity and better stability of the conductivity in time to the conductive polymer~ ~ompounds having the de~ired effect are for instance paratoluenesulphonic acid and salt~ and substituted form~ thereof and anthraquinone.

21~6730 - 11 - AE 74~5 Excess oxidant and dispersant preferably are removed from the dispersion after the polymerisation of the conductive polymer by ultrafiltration centrifuging, precipitation or other separation techniques known per se.
The monomeric units from which the eventual electrically conductive polymer in the dispersion of electrically conductive particles according to the invention is composed are for example chosen from the group comprising pyrrole, thiophene, indole, carbazole, furan, benzene, aniline, acetylene, and derivatives of these monomers. In view of the level and the stability of the conductive properties an electrically conductive polymer composed of pyrrole, thiophene or aniline units or derivativQs of these monomer~ is preferable.
Examples o~ derivatives of these monomers are N-methylpyrrole, N-ethylpyrrole, N-n-propylpyrrole, N-n-butylpyrrole, N-phenylpyrrole, N-tolylpyrrole, N-naphthylpyrrole, 3-methylpyrrole, 3,4-dimethylpyrrole, 3- -ethylpyrrole, 3-n-propylpyrrole, 3-n-butylpyrrole, 3-phenylpyrrole, 3-tolylpyrrole, 3-naphthylpyrrole, 3-methoxypyrrole, 3,4-dimethoxypyrrole, 3-ethoxypyrrole, 3-n-propoxypyrrole, 3-phenoxypyrrol e, 3-methyl-N-methylpyrrole, 3-methoxy-N-methylpyrrole, 3-chloropyrrole, 3-bromopyrrole, 3-methylthiopyrrole, 3-methylthio-n-methylpyrrole, 2,2~-bithiophene, 3-methyl-2,2'- -~
bithiophene, 3,3'-dimethyl-Z,2'-bithiophene, 3,4-dimethyl-2,2'-bithiophene, 3,4-dimethyl-3',4'-dimethyl-2,2'-bithiophene, 3-methoxy-2,2'-bithiophene, 3,3'-dimethoxy-2,2'-bithiophene, 2,2',5,2''-terthiophene, 3-methyl-2,2',5',-2''terkhiophene, 3,3'-dimethyl-2,2',5',2''-terthiophene, 2-cyclohexylaniline, aniline, 4-propanoylaniline, 2-(methylamino)aniline, 2-(dimethylamine)aniline, o-toluidine, 4-carboxyaniline, n-methylaniline, m-hexylaniline, 2-methyl 4-methoxy-carbonylaniline, n-propylaniline, n-hexylaniline, m-toluidine, o-ethylaniline, m-ethylaniline, o-ethoxyaniline, m-butylaniline, 5-chloro 2-ethoxyaniline, 2~0~7~0 m-octylaniline, 4-bromoaniline, 2-bromoaniline, 3-bromoaniline, 3-acetamidoaniline, 4-acetamidoaniline, 5-chloro-2-methoxyaniline, 2-acetylaniline, 2,5- -dimethylaniline, 2,3-dimethylaniline, N,N-dimethylaniline, 4-benzylaniline, 4-aminoaniline, 2-methyl-thiomethylaniline, 4-(2,~-dimethylphenyl)aniline, 2-ethyl-thioaniline, n-methyl-2,4-dimethylaniline, n-propyl-m-toluidine, n-methyl-o-cyanoaniline, 2,5-dibutylaniline, 2,5-dimethoxyaniline, o-cyanoaniline, tetrahydronaphthylamine, 3-(n-butanesulphonic acid) aniline, 2-thiomethylaniline, 2,5-dichloroaniline, 2,4-dimethoxyaniline, 3-propoxymethylaniline, 4-mercaptoaniline, 4-methylthioaniline, 3-phenoxyaniline, 4-phenoxyaniline, n-hexyl-m-toluidine, 4-phenyl-thioaniline, n-octyl-m-toluidine, tetrahydrobenzo[c]-thiophene, 4-trimethylsilylaniline and 3,4-(alkylene-vic-dioxy)thiophene.
Optionally the electrically conductive polymer i~ composed from a mixture of several of the aforQmentioned monomeric units.
The dispersing medium is chosen so that both the binder and the electrically conductive polymer do not or virtually not dissolve in it. The catalyst and the monomeric units from which the electrically conductive polymer is composed can however dissolve in the dispersing medium. The dispersing medium i often ehosen from the group comprising water, aromatic compounds, for example benzene, toluene and xylene, alcohols, for example methanol and ethanol, hydrocarbon~, for example pentane and hexane, ethers, for example dioxane, diethylether, ethyl methyl ether and tetrahydrofuran, ketones, for example acetone, diethyl ketone and methyl ethyl ketone, halogenated compounds, for example CHCl3, CH2Cl2 and hydrocarbon tetrachloride, esters, for example ethylformiate and ethylacetate and compounds like acetonitrile, nitromethane, dimethyl sulphoxide, dimethylformamide, triethylphosphate, dimethylacetamide , :: .: ~ , ~ , . ,~ ", " ~ : ", . ~ " . ~

21~730 and pyridine. It is also pos~ible to use a mixture of several dispersing mediums. For environmental reasons it is preferable to use water as the dispersing medium.
In a special embodiment the aforementioned monomers are obtained via in-situ deblocking of precursor monomers. A precursor monomer is a molecule that is incapable of polymerising as such due to the presence of a -sllbstituting group at one of the places involved in the polymerization. After a simple conversion step this molecule is however converted into a polymerisable monomeric unit. This conver~ion step may comprise the removal of a blocking group which shields one or more reactive sites. The removal of an electron-attracting group which increases the oxidation potential of the molecule, as a result of which polymerisation is prevented, is also pos~ible. In another embodiment an intramolecula~ reaction takes place, for example a retro-Diels-Alder reaction, to convert a precursor monomer into a polymeri able monomeric unit. Any precursor monomer ;-which after activation becomes a polymerisable monomeric unit from which an electrically conductive polymer can be formed is suitable for use.
Examples of suitable precursor monomers are molecules having a structure according to Formula (I):

~R2 ~S . .
~ Formula (I), where X is -~-, -S- or -O-;
H
Rl is hydrogen, -C(O)OH, -C(O)C(O)OH, -C(O)H, -SO3H, -I or Br;
R2 is hydrogen, an alkyl group (with l-10 carbon atoms), -C[O)OH or a halogen;

21~6730 R3 is hydrogen, an alkyl group (with 1-10 carbon atoms), -C(O)OH or a halogen;
R4 is hydrogen, -C(O)OH, -C(O)C(O~O~, -C(O)H, -SO3H, -I or -Br;
R5 is hydrogen or an alkyl, aryl, alkoxy or silyl group;
on the understanding that Rl and R4 are not ~imultaneously hydrogen and that R2 and R3 may both form part of a closed ring structureO
Preferably use is made of pyrrole-2-carboxylic -acid. The synthesis of this precursor monomer is described in J.Am.Pharm. Assoc. 45, 509 (1956).
All combinations of X, Rl, R2, R3 and R4, not excluded above, are pos~ible. Groups Rl and R4 may be thermally or photochemically eliminated with the formation of a pyrrole, whether or not substituted at position R2 and/or R3, a thiophene or a furan monomer. This precursor monomer is hence deblocked and can then freely polymerise via the Rl and R4 positions. Groups R2 and R3 may be the same or different. Groups R2 and R3 may also both form part of a closed ring structure. A suitable example of such a precursor monom~r is 3,4-(alkylene-vic-dioxy-)thiophene-2,5-dicarboxylic acid. -Other suitable precursor monomers with which an clectrically conductive polymer can be prepared are procursor monomers having a structure according to Formula k, ~ ~ Formula (II), ~l ~ x~
~ ' ..
where ~
Xl and x2 are the same or different and are -p-, -S- or -O_; R4 Rl and R2 are the same or differQnt and are hydrogen or an alkyl group with 1-10 carbon atoms;
R3 is hydrogen or an alkyl, aryl or alkoxy group.
'.

'~' . . . ., , , . . , ~ ,. ..
,i . ., ,, , , , , " , . . :, . .

The precursor monomers according to Formula (II) can for example be synthesized as described in J.Chem.Soc.
Perkin Trans. I (1985), pp. 1277-1284. Another suitable precursor monomer is 4-aminobenzoic acid (see P. Ruelle, 7.Chem.Soc.Perkin trans.II, 1953 (1986)). It is also possible to use 3,4-disubstituted thiophenes (see for example US-A-4,987,0~2).
Combinations of all kinds of precursor monomers are possible. Optionally use can also be made of precursor -oligomers. ~he precursor monomers can for example be activated via a thermal or a photochemical treatment.
The weight ratio of the electrically conductive polymer and the binder may vary within a wide range, dependent on the desired electrically ~onductive lS properties on the one hand and the coating properties on the other. Usually this ratio lies between 0.1:99.9 a~d 80:20; preferably it lies between 0.1:99.9 and 20:80; more preferably it lies between 0.1:99.9 and 10:90.
Dependent on the electrically conductive polymer obtained the electrically conductive properties can be improved via an (oxidative or reductive) doping step, by using the known doping methods ancl doping reagents. They are for example mentioned in the 'Handbook of conducting polymer~' (T.A. Skotheim, Marcel Dekker Inc., New York, USA (1986)). Doping is effected for example by adding a doping agent to the di persion of electrically conductive particles.
Optionally up to 60 and even up to 90 wt.~
fillers and/or antioxidants can be added to the dispersion of electrically conductive particles according to the invention. Examples of fillers to be added are talc, barium sulphate, calcium carbonate, fibres, (light- -- absorbing) pigments, for example titanium white and coloured pigments such as iron oxide and SiO2, kaolin, wollastonite and glass. In addition adhesion-promoting agents, flow-promoting agents, thickeners, surface-improving agents, anti-foaming agents, anti-corrosion ' . .,~'. ': .

21~730 agents, hardeners, drying agents, conducting materials, for example soot, conducting fibres and conducting flakes, stabilisers and binders may be added. It is also possible te remove the dispersing medium from the dispersion of conductive particles, e.g. by freeze drying or evaporation, and to use those particles in common proc~ssing methods for solid polymeric materials.
The conductive coatings or other conductive products can be used as shielding material against electromagnetic interference and electrostatic discharges.
Other applications are for example those mentioned in Progr. Org. Coat. 19, 21, 1991 by M. Aldissy and S.P.
Armes.
The invention is further elucidated with ref~rence to the following examples and comparative experiment~ without being limited thereto.
The conductive properties of the products are for example determined with the aid of the so-called four-probe method. A detailed description is given by H.H.
Wieder in Laboratory Notes on Electrical and Galvanomagnetic Measurements, Elsevies, New York, 1979.
Thi~ method measures the specific conductivity:

u = (L/A) * (1/R) where ~ = specific conductivity [s/cm];
L 8 distance between the two inside electrodes [cm];
R = resistance [ohm];
A = cross-sectional area [cm2]
ExamPles and compa~ativyL~ rl~n~

35 Example I ~ `
A ~olution was prepared o~ 4.86 g of FeCl3 (from Merck, free of water) in 21.25 q of demineralised water 7 ~ 0 (solution A). Then a solution was prepared of 0.89 9 of pyrrole (from Aldrich, vacuum distilled) in 19.34 g of demineralised water (solution B).
At a temperature of 20C solution A was added drop ~y drop to 20 g of a dispersion of polyurethane in water (Uraflex XP 401 UZ, DSM Resins, solids content 40%, average particle size 60 nm), which was stabilised by incorporated methoxypolyethyleneglycol chains (M~ = 750 g/mole). The drops were added while the dispersion was stirred with the aid of a stirring bar. During the addition of the drops the temperature was kept at 20C. -The colour of the dispe~sion was yellow/green.
After half an hour's stirring solution B was added drop by drop, with stirring. After solution B had been added the colour of the dispersion changed to dark green and then to black.
After 20 hours' stirrinq at a temperature of 20C a portion of the dispersion was centrifuged for half an hour at 20,000 rpm. Then the supernatant layer of water was poured off and the sediment (2.63 g) was redisper~ed in 5.17 g of demineralised water with the aid of an Ultra-?orrax T 25 (Janke & Kunkel JR Labortechnik). The di~persion thus obtained was then spread out to a fluid film on a glass plate and dried to the air at room temperature.
Finally the spQcific conductivity of the obtained film, that appeared to be homogeneous, was determined: 0.3 S/cm. ~
,~ ':' .
Exam~le II
A solution was prepared of 10.88 g of FeCl tfrom Merck, free of water) in 47.64 g of demineralised water (solution A). Then a solution was prepared of 2.11 g of pyrrole (from Aldrich, vacuum distilled) in 37.90 g of damineralised water (solution B). ;
In the same manner as in Example I the two solutions were added to 20 g of a dispersion of polyurethane in water (Uraflex XP 401 UZ, DSM Recins, solids content 40~, avera~e particle size 60 nm), which ~106730 was stabilised by incorporated methoxypolyethylene glycol chains (Mw = 750 g/mole). After a portion of the disper ion had been centrifuged 3.42 g of sediment was redispersed in 5.68 g of demineralised water. The dispersion thus obtained was then spread out to a fluid film on a glass plate and dried to the air at room temperature. Finally the specific conductivity of the obtained film, that appeared to be homogeneous, was determined: 0.2 S/cm.
ExamPle III
A solution was made of 2.30 g of FeC13 (from Merck, free of water) in 10.05 g of demineralised water (solution A~. Then a solution was prepared of 0.46 g of pyrrole (from Aldrich, vacuum distilled) in 9.77 g of demineralised water (solution B~.
In the same was as in Example I the two solutions wer~ added to 20 g of a dispersion of polyurethane in water (Uraflex XP 401 UZ, DSN Resins, solids content 40~, average particle size 60 nm), which wa3 stabilised by incorporated methoxypolyethylene glycol chains (Mw = 750 g/mole). After it had been centrifuged, 1.99 g of sediment was redispersed in 3.97 g of demineralised water. The black di~;persion thus obtained `~
was then spread out to a fluid film on a glasR plate and driQd to the air at room temperature. Finally the specific conductivity of the obtained film, that appeared to be homogeneous, was determined: 0.07 S/cmO

ComDarative experiment A
A solution was prapared of 3.34 g of FeCl3 (from Merck, free of water) in 15.0 g of demineralised water (solution A). Solution A waR added drop by drop to 20 g of a dispersion of polyurethane in water (Uraflex Z~ 2331, DSM Resins, solids content 40~, average particle size 100 nm), which was stabilised by ionic carboxyl groups on the polyurethane chain. During the addition of the drops the dispersion was atirred with the aid of a stirring bar.

2~73Q

During the addition of the drops the temperature was kept at 20C. After 1.15 g of FeCl3 solution had been added the dispersion became unstable and lumps started to be formed.
It proved impossible to obtain a homogeneously distributed film of thi~ dispersion.

Example IV
A solution was prepared of 11.67 g of FeCl3 (from Merck, free of water) in 57.92 g of demineralised water (solution A). Then a solution was prepared of 2.11 g of pyrrole (from Aldrich, vacuum distilled) in 32.38 y of demineralised water (Rolution B).
In the same manner as in Example I the two solutions were added to 20 g of a~ emulsion of alkyd resin in water (Uradil AZ 600, DSM Resins, solids content 42~, average particle size 300 nm), which was stabilised by incorporated methoxypolyethylene glycol chains (Nw = 4,000 g/mole).
The drops were added while the diispersion was stirred with the aid of a stirring bar. During the addition of the drops the temperature wa~ kept at 20C. After centrifugation 3.42 g of sediment was redispersed in 5.68 g of demineralised water. The black dispersion thus obtained was then spread out to a film on a glas~ plate and dried to the air at a temperature of 70C. Finally the i~pecifi~ conductivity of the obtained film, that appeared to be homogeneous, was determined: 0.06 S/cm.
:
Exam~le V ~!
A solution was prepared of 5.20 g of FeC13 ~from Merck, free of water) in 25.80 g of demineraliRed water (~olution A). Then a solution was prepared of 0.93 g of i-pyrrole (from Aldrich, vacuum distilled) in 18.96 g of demineraliqied water (solution B).
In the same manner as in Example IV the two solutiona were added to 20 g of Uradil AZ 600, which was ~tabili~ed by incorporated methoxypolyethylene glycol , . :.

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~06~3 0 AE 7495 chains (Mw = 4,000 g/mole). The black redispersed sediment thus obtained was then spread out to a film on a glass plate and dried to the air at 70C. Finally the specific conductivity of the obtained film, that appeared to be homogeneous, was determined: 0.01 S/cm.

Comparative ex~eriment B
1.3 g FeCl3 solution (18 wt.~ in water) was added drop by drop, with stirring, to 20.0 ~ of a di~persion of alkyd resin Z310 (Dsn Resins, 60 wt.%
solids; average particle si~e 534 nm), which was stabilised by 2 wt.~ sodium dodecylbenzene sulphonate. The emulsion immediately became unstable.

Com~arative experiment C
3.4 g of an FeCl3 solution (18 wt.% in water) was added drop by drop, with stirring, to 20.0 g of a dispersion of alkyd resin Z310 (DSM Resins, 5 wt.% ~olids;
average particle size 534 nm), which was ~tabilised by 2 wt.~ sodium dodecylbenzene sulphonate. The emulsion immediately became unstable.
'.
Example VI
18.0 g of FeCl3 solution (18 wt.% in water) was addad drop by drop, with stirring, to 20.1 g of acrylate disperæion on the basis of methylmethacrylate, butylacrylate and methacrylic acid,stabili~ed by 7 ~-by weight of built-in methoxy poly(ethylene glycol) (Mw = 750 g/mole) and emulgated by alkylbenzene sulphonate in an amount of 0.7 %-by-weight with re3pect to the amount of acrylate. The average particle eize is 495 nm. This acrylate will be denoted as Uramul PD/STA 71 in the following examples. Then the dispersion was stirred for 30 minutes at a temperature of 20C. At the same temperature 11.6 g of pyrrole solution ( 5 wt.~ in water) was then added drop by drop, with stirring. A stable black dispersion was formed. After centrifugation and :~ " ' .' :.' '~ ,. '~'. '~. ''; ,,.''; '~ , ' ~ ` '~ ',~'~" "~,, ""~ , . " ~ .."~, ", ;,~ ", " ~" ;,~

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21~30 redispersion of a portion of the black dispersion thus obtained was then spread out to a film on a glass plate and dried to the air at 80C. Finally the specific conductivity of the obtained film, that-appeared to be homogeneous, was determined: 2 * 10-5 S/cm.

Example VII
3.5 g of FeC13 solution (lB wt.~ in water) was added drop by drop, with stirring, to 20.0 9 of acrylate dispersion (Uramul PD/STA 71; 5.0 wt.~ solids; average particle size 495 nm). Then the dispersion was stirred for 120 minutes at a temperature of 20C. At the same temperature 2.3 g of pyrrole solution (5 wt.% in water) was then added drop by drop, with stirring. A stable black dispersion was formed.

Com~arative experiment D
A solution was prepared of 4.99 g of FeCl3 (from Merck, free of water) in 22.47 g of demineralised water (solution A). Then a solution waq prepared of 0.89 g of pyrrole (from Aldrich, vacuum distilled) in 16.89 g of demineralised water (solution B). ;~
After solution A had cooled to a temperature of 20C it was added drop by drop to 20.04 9 of a dispersion of an acrylate resin in water (Uramul CP 3310 SC, DSM
Resins, solids content 50~, average particle size 170 nm), which was stabilised by added ether sulphate. During the addition of the drops the dispersion was stirred with the aid of a stirring barO During the addition of the drops tha temperature was kept at 20C. After half an hour's stirring solution B was then added drop by drop, with stirring. After 4.19 g of solution B had been added a black precipitate had been formed, which could not be redispersed.

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Exam~le VIII
19~90 g of a polyurethane dispersion in water (Uraflex XP 401 UZ, ~SM Resins, solids content 40~, average particle size 60 nm), which was stabilised by incorporated methoxypolyethylene glycol chains (~w=750), was introduced into a beaker and stirred with the aid of a stirring bar. The beaker was placed in a vessel containing ice. Then the dispersion was acidified by adding a HCl solution (1.37 y of 12 molar + 13.42 g of 1 molar) in water.
Then 0.89 g of aniline, dissolved in 17.03 g of lM HC1, was added drop by drop, with stirring. Finally 1.61 g of (NE4 ) 2S20B, dissolved in 15.08 ~ of lM HCl, was added with stirring.
After 24 hours the obtained dark green dispersion was centrifugad (20,000 rpm, 30 minutes). After centrifu~ation the aqueous phase was poured o~f and the sediment was redi~per6ed. From this a coating was made, whose specific co~ductivity was measured after drying: 1.5 S/cm.
Example IX
A solution was prepared of 3.61 g of FeCl3 (Merck, free of water) in 16.26 g of demineralised water (solution A~. Then a ~olution was prepared of 0.60 g of pyrrole (from Aldrich, vacuum distilled) in 12.19 g of demineralised water (~olution B).
In the same way as in Example I the two solution~ werQ added to 20.06 g of vinyl acetate dicpersion in water (Uramul VH10, DSM Resins, solids content 29~, stabilised with the aid of partly chemically bound hydroxymethyl celluloQe, average particle size 550 nm).
After centrifugation 4.35 g of sediment was redispersed in 10.15 g of demineralised water. Of this dispersion a homogeneous coating was applied to a glass plate, after which, after drying at room temperature, the specific conductivity was measured: 6 * 10-5 S/cmO ~-~ ~673 ~ AE 7495 .
Example_X
A solution was prepared of 12.32 g of Fe(N03)3.9H20 (Janssen Chimica, p.a.) in 234.2 g of demineralized water (solution A). Subsequently, a solution was prepared of 0.89 g of pyrrole (Aldrich, vacuum distilled) in 43.6 g uf distilled water.
Analogously to example I, both solutions were added to 20 g of a dispersion of polyurethane in water (Uraflex XP 401 UZ, DSM Resins, solids content 40%, -average particle size 60 nm), stabilized by means of incorporated methoxy polyethylene glycol chains (N~ = 750 g/mole). After the dispersion had been centrifuged for one hour at a speed of 14,000 rpm, the sediment was redispersed. The resulting dispersion was pour~d out onto a glass plate and dried (T = 80C in N2 environment), yielding a coating with a specific conductivity of 0.37 S/cm. ;
, Example XI
Example X was repeated, solution A now consisting of 8.69 g of Fe(p-toluene sulphonate) dissolved in 117.14 g of demineralized water. The coating prepared from this solution has a specific conducti~ity of-7.5 S/cm and the stability of its conductivity properties proved to be good.
~ .
Example XII
Example I was repeated, but during addition of solution A and solution B and during stirring the temperature was now kept between 0 and 5C by means of an ice bath.
The specific conductivity of the coating obtainQd after drying at a temperature of 80C was 2.5 S/cm. -~

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21 0~730 Example XIII
Analogous to example X, the difference being that after addition of solution B stirring was applied for one hour, following which the di~persion was centrifuged.
The specific conductivity of the coating film obtained wa~c 0.28 S/cm~

Exam~le XIV
2.0 g of white pigment paste (31.5 mass %
polyurethane dispersion (Uraflex XP 401 UZ from DSM
Resins)), 52.5 mass ~ titanium dioxide (Tioxide TR 92 from --Tioxide International)), 15.7 mass % water and 0.3 mass anti-foaming agent (Tego foamex 7447 from Tego Chemie Service)) were added to 1.0 g of the dispersion of example X (solids content 12.9 mass ~). After drying, a grey coating having a specific conductivity o~ ~ x 10-3 S/cm was obtained.

Example XV
A solution was prepared of 0.75 g of H202 solution (Perhydrol 30~ ~22~ p.a., from Merck) in 0.75 g of demineralized water (solution A). Subsequently, a solution was prepared of 2.58 g of p-toluene sulphonic acid monohydrate (99%, from Janssen Chimica) in 7.50 g of demineralized water (solution B). In additio~, a solution was prepared of 0.01 g of FeCl3 (from Merck, anhydrous) in 0.66 g of demineralized water (solution C).
At a temperature of 20C 0.45 g o~ pyrrole (from Aldrich, vacuum distilled) was added to a diluted acrylate ;~
dispersion (~ramul PD/STA 71; 5.0 wt.~ solids), stabilized by mQans of 7 wt.% incorporated methoxy polyethylene glycol (Mw = 750 g/mole). Addition took place while the dispersion was bein~ stirred by meanR of a stirring bar. -During addition the temperature was kept at 20~C.
After the pyrrole had dissolved, solutions A and B wsre added. Subseguently, solution C was added with stirr ing.
, ' '", '' 21~7~0 After four hours' stirring the dispersion was spread out on a glass plate to obtain a film, which was dried at a temperature o~ 80C under N2. The specific conductivity of the film wais found to be 1.1 x 10-2 S/cm.
The examples show that the stability of : .
dispersions whose binder is stabilised by means of a non-ionic stabiliser is very good. The dispersions according to the invention are also very suitable for providing, in a simple manner, objects with a coating that has both good electrically conductive properties and good coating properties. The applied coating is homogeneously distributed over the coated object and moreover appears to adhere well to the object.

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Claims

1. Dispersion of electrically conductive particles, comprising a binder and an electrically conductive polymer in a dispersing medium, characterised in that the particles contain a non-ionic stabiliser.

2. Dispersion according to claim 1, wherein the binder is a non-doping polymer.

3. Dispersion according to claim 1 or 2, wherein the non-ionic stabiliser is chemically bound to the binder.

4. Dispersion according to any one of claims 1-3, wherein the electrically conductive polymer is substantially adsorbed to the surface of the particles.

5. Dispersion according to any one of claims 1-4, wherein the dispersion contains 1-50 wt.% non-ionic stabiliser, relative to the overall weight of binder and stabiliser.

6. Dispersion according to any one of claims 1-5, wherein the molecular weight of the non ionic stabiliser lies between 500 and 5000 g/mol.

7. Dispersion according to any one of claims 1-6, wherein the non-ionic stabiliser is composed of monomeric units containing 1-20 carbon atoms.

8. Dispersion according to any one of claims 1-7, wherein the non-ionic stabiliser is chosen from the group comprising polyoxyalkyl esters and polyoxyalkyl ethers.

9. Dispersion according to claim 8, characterised in that the non-ionic stabiliser is polyethylene glycol or methoxy polyethylene glycol.

10. Dispersion according to any one of claims 1-9, wherein the weight ratio of the electrically conductive polymer and the binder lies between 0.1:99.9 and 20:80.

11. Dispersion according to any one of claims 1-10, wherein the binder is chosen from the group comprising alkyd resins, polyester resins, polyurethane resins, acrylate resins, vinylacetate containing resins and hybrid systems containing said resins.

12. Dispersion according to any one of claims 1-11, wherein the electrically conductive polymer is composed of monomeric units from the group comprising pyrrole, thiophene, aniline, and derivatives of these monomeric units.

13. Process for the preparation of the dispersion according to any one of claims 1-12, according to which the monomers are polymerised to an electrically conductive polymer in a dispersion of a binder, which contains a non-ionic stabiliser.

14. Process for applying a conductive coating, comprising the process of claim 13.

15. Use of the dispersions according to any one of claims 1-12 for applying a conductive coating.

16. Coating entirely or partly made from the dispersion according to any one of claims 1-12.

17. Coating according to claim 16, characterised in that the specific conductivity is at least 10-10 S/cm.

18. Coating according to claim 17, characterised in that the specific conductivity is at least 10-3 S/cm.

19. Dispersion and process as substantially described and explained with reference to the examples.