A coating composition useful in forming conductive layers comprises a latex having water as a continuous phase and, as a dispersed phase, hydrophobic polymer particles having associated therewith a polyaniline salt semiconductor. The coating composition can be coated on a variety of supports to produce conductive elements. The coating compositions are particularly useful in forming antistatic layers for photographic elements or conducting layers for electrophotographic and electrographic elements. Also disclosed is a preferred process for preparing a latex coating composition comprising the steps of loading polymer particles with the polyaniline component of the polyaniline acid addition salt semiconductor and then acidifying the latex to form a polyaniline salt coating composition.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to new conductive compositions, elements and 
processes. More specifically, the conductive compositions of the present 
invention are dispersions of hydrophobic latex polymer particles having 
associated therewith polyaniline acid addition salt semiconductors. 
Processes for making polyaniline saltcontaining latices and methods for 
preparing elements having coatings of the compositions form other aspects 
of the present invention. 
2. Description Relevant to the Prior Art 
The unwanted buildup of static electricity on an insulating support has 
been a continuing problem. It is well-known that a thin conductive layer 
will prevent static buildup but, while it is possible to formulate a 
conductive composition that can be coated on a support, it has been quite 
difficult to combine these conductive properties with other desirable 
physical properties. 
The stringent physical and optical requirements for photographic elements 
make the formulation of suitable antistatic compositions for these 
elements particularly troublesome. Many conductors are known which can be 
coated on photographic elements to provide static protection. One 
particularly useful class of compositions which can be used in 
photographic elements is a composition containing the polyaniline acid 
addition salt (hereinafter "polyaniline salt") semiconductor described in 
U.S. Pat. No. 3,963,498 issued June 15, 1976, to Trevoy. These 
semiconductors are formed by the reaction of a neutral polyanilineimine 
(hereinafter "polyaniline") with an acid. These semiconductors offer a 
number of advantages when used in antistatic coatings, particularly when 
used with photographic films. For example, because these materials are 
electronic conductors as opposed to ionic conductors, their conductivity 
is relatively independent of relative humidity. Thus, they retain high 
conductivity under conditions of low humidity where the buildup of 
unwanted static electricity is particularly difficult to control. Further, 
these semiconductors retain their conductivity when coated in a suitable 
binder and therefore can be used in a variety of elements using 
conventional coating techniques. Still another advantage of these 
semiconductors is that they are relatively inexpensive and therefore can 
be used on a relatively large scale at low cost. 
The polyaniline salt semiconductors of Trevoy offer a number of advantages; 
however, further improvements have been sought. While coatings containing 
a relatively low coverage of these semiconductors are useful in reducing 
the resistivity of an insulating support to a certain extent, relatively 
high coverages of these semiconductors, when used in conventional coating 
compositions, are required to achieve sufficient conductivity to eliminate 
static problems under severe conditions. For example, in order to achieve 
resistivities on the order of 10.sup.6 ohm/sq, it is necessary to coat the 
semiconductors of Trevoy at coverages greater than about 35 mg/m.sup.2. 
Unfortunately, these semiconductors are colored and at these coverages 
impart to the elements on which they are coated an undesirable density. As 
an illustration, a coating containing 35 mg/m.sup.2 of a typical 
semiconductor disclosed in the Trevoy patent, e.g., 
N-{p-[(4-methoxyanilino)anilino]phenyl}-1,4-benzoquinone imine 
p-toluenesulfonic acid salt, would have a highly desirable conductivity of 
about 1.0.times.10.sup.8 ohm/sq, but would also have an integrated optical 
density of about 0.025 in the visible portion of the spectrum. If the 
coverage of the polyaniline salt in such a layer were to be reduced so as 
to reduce the undesirable optical density, the resistivity would increase. 
For certain critical applications such as, for example, in the production 
of transparent photographic materials, it would not be possible to get 
sufficiently high conductivity while at the same time desirable low 
optical density. It is readily apparent that improvements in the 
semiconductive coating compositions would be extremely desirable. 
Aside from the optical density problems associated with the semiconductors 
of Trevoy, these semiconductors are, in general, insoluble in water. This 
can be undesirable because coating layers onto photographic supports is 
more safely and economically accomplished if water can be used as the 
basis for the coating composition. Extensive milling permits dispersions 
of water-insoluble semiconductors to be made in the presence of protective 
colloids such as gelatin. However, milling in this manner is 
time-consuming and energy-intensive. It would be highly desirable if a 
suitable method of coating semiconductors from water could be devised. 
It is known to use latex dispersions as binders for conductive materials. 
In conventional processes such as those described in U.S. Pat. 4,011,176, 
the antistatic materials, such as semiconducting compounds, are simply 
dispersed in the continuous phase, along with the latex particles. This 
usually requires extensive mixing and/or milling in order to disperse 
water-insoluble antistatic material. When this is attempted with 
polyaniline salt semiconductor antistatic materials, it produces a useful 
aqueous-based coating composition. However, when the latex is coated and 
coalesced on a support, high coverages of the polyaniline salt 
semiconductor are still required to produce the desired high conductivity. 
This high coverage again results in undesirable density. 
While for many reasons semiconductors are highly desirable in photographic 
elements, the prior art does not suggest a solution to the difficult 
problems discussed above. There is no suggestion as to how these 
semiconductors can be coated from aqueous solutions in order to produce 
high-conductivity coatings. 
SUMMARY OF THE INVENTION 
We have found that the above difficult problems can be substantially 
reduced by preparation of a coating composition which uses a polyaniline 
salt semiconductor, the composition being prepared by particular methods 
using particular materials. By using the materials and methods described 
herein, we are able to produce an aqueous-based coating composition which 
is capable of forming coatings having, at the same time, high conductivity 
and low optical density. In one aspect of our invention, we provide an 
element comprising a support having thereon a conductive layer, the 
conductive layer comprising a coalesced, cationically stabilized latex 
binder and a polyaniline salt semiconductor formed by the reaction of a 
polyaniline and an acid. The improvement according to our invention is 
that the semiconductor and the latex are chosen so that the semiconductor 
is associated with the latex before coalescing. 
The coating composition which forms the layer described above is another 
important aspect of our invention. The coating composition comprises a 
latex having water as a continuous phase and, as a dispersed phase, 
cationically stabilized hydrophobic polymer particles having associated 
therewith the semiconductor. The key to the present invention is that, in 
order to produce layers having high conductivity at low coverage, it is 
necessary that the semiconductor be associated with the hydrophobic latex 
particle in the coating composition. By "associated with" we mean that the 
semiconductor is attached to or located within the polymer particle; that 
is, the semiconductor is not merely mixed or dispersed with the latex 
dispersion as is known in the art, but must become a part of the 
individual polymer particles. Thus, substantially all of the semiconductor 
in the coating composition must be adsorbed, absorbed or otherwise become 
an integral part of the polymer particles. By preparing a coating 
composition wherein the semiconductor is associated with the latex 
particles, we are able to produce coatings having unexpectedly high 
conductivity at low coverages. 
Another aspect of our invention is a preferred process for associating the 
semiconductor with the polymer particles in the latex. While other 
processes can be used, the process of the present invention is 
particularly preferred. The process comprises the steps of: 
(1) forming a solution by dissolving a polyaniline in a water-miscible 
organic solvent, 
(2) forming a latex by dispersing cationically stabilized hydrophobic 
loadable polymer particles in an aqueous continuous phase, 
(3) blending the latex with the solution, 
(4) loading the polymer particles by removing the organic solvent thereby 
forming a polyaniline-loaded latex, and 
(5) forming a polyaniline salt-loaded latex by adding sufficient acid to 
the polyaniline-loaded latex to convert substantially all of the 
polyaniline-loaded latex to polyaniline salt-loaded latex. 
In yet another aspect of the present invention, we provide a process of 
preparing a conductive element comprising a support having thereon a 
conductive layer, the process comprising the steps of: 
(1) forming the latex coating composition described above, 
(2) coating the latex on a support, 
(3) removing the continuous phase of the latex and 
(4) coalescing the latex so as to form the layer. 
Using the coating compositions and processes of our invention, the layers 
of our invention can be highly conducting while at the same time have very 
low coverages of the semiconductor. This means a savings in materials in 
the coating process and coatings with very low optical density. These 
advantages are obtained with coating compositions which can be easily and 
safely coated because of their aqueous base. 
Further, the layers of our invention unexpectedly exhibit highly uniform 
conductivity over the surface of the layer. 
DETAILED DESCRIPTION OF THE INVENTION 
According to the present invention, the semi-conductor must be associated 
with the hydrophobic latex particle in the coating composition. Layers 
coated from such coating compositions have desirable high conductivity at 
low coverages. One particularly preferred method of preparing the polymer 
particles having the polyaniline salt semiconductor associated therewith 
is to load the particles with the semiconductor according to an adaptation 
of the method described by Chen in Research Disclosure, No 15930, Vol 159, 
July, 1977. It is preferred to adapt the process of Chen by first forming 
a polyaniline-loaded latex and then converting this latex to a polyaniline 
salt-loaded latex by treatment with acid. The adapted process of Chen is 
particularly preferred when used with the polyaniline salt semiconductor 
because large quantities of the semiconductor can be associated with the 
polymer particles using this method. 
The preferred adapted loading process is a five-step process. First, a 
solution is formed by dissolving a polyaniline in a water-miscible organic 
solvent. Second, a latex is formed by dispersing hydrophobic loadable 
polymer particles in an aqueous continuous phase. Third, the latex is 
blended with the solution of the polyaniline. Fourth, the polymer 
particles are loaded by removing the organic solvent. This step forms a 
polyaniline-loaded latex. Finally, in the fifth step, the 
polyaniline-loaded latex is converted to a polyaniline salt-loaded latex 
by acidifying the latex with a suitable acid. The resulting polyaniline 
salt-loaded latex forms an excellent coating composition having a 
semiconductor associated with the latex polymer particles. A useful 
conductive element can be prepared by coating the described latex coating 
composition on a suitable support, removing the continuous phase of the 
latex and coalescing the latex so as to form a conductive layer on the 
support. 
The polyanilines which can be used to form the coating compositions and 
elements of the present invention are described in U.S. Pat. No. 3,963,498 
to Trevoy, the entire disclosure of which is hereby incorporated by 
reference. More particularly, the polyaniline component is the D moiety 
which is described by Trevoy in column 3, line 15, through column 6, line 
8. Specific useful polyanilines can be found in Table 1 of the patent at 
column 6, line 63, through column 7, line 30. While all of the 
polyanilines described by Trevoy can be used in the preferred compositions 
and elements of the present invention, the preferred imines are 
N-{p-[4-(p-methoxyanilino)anilino]-phenyl}-1,4-benzoquinone imine 
(polyaniline (a)), N-{p-[p-(anilino)anilino]phenyl}-1,4-benzoquinone 
diimine (polyaniline (b)) and 
N-{p-[4-(p-methylanilino)anilino]}phenyl-1,4-benzoquinone imine 
(polyaniline(c)). 
In order to form the loaded latex which is useful as the preferred coating 
composition of the present invention, the polyaniline or semiconductor is 
dissolved in a water-miscible organic solvent. Useful solvents are those 
which: 
(a) can be dissolved in distilled water at 20.degree. C. to the extent of 
at least 20 parts by volume of solvent in 80 parts by volume of water; 
(b) have boiling points (at atmospheric pressure) above about -10.degree. 
C.; 
(c) do not detrimentally react chemically or physically with latex polymer 
or the semiconductor and 
(d) do not dissolve more than about 5 weight percent of the loaded polymer 
particles at 20.degree. C. 
Useful water-miscible organic solvents are water-miscible alcohols, ketones 
and amides, tetrahydrofuran, N-methyl-2-pyrrolidone, dimethylsulfoxide and 
mixtures thereof. Particular examples of these solvents include acetone, 
ethyl alcohol, methyl alcohol, isopropyl alcohol, dimethylformamide, 
methyl ethyl ketone and the like. The polyanilines are generally soluble 
in acetone and this is the preferred solvent for the preferred process. 
Useful latex polymers, in addition to being capable of associating with the 
semiconductor, should meet several requirements. The latex polymers must 
be cationically stabilized and should have a glass transition temperature 
less than about 65.degree. C. The polymer particles should be capable of 
forming a fully coalesced layer under conditions which do not degrade the 
physical or chemical properties of the support. 
The aqueous latices which are the preferred coating compositions consist 
essentially of water as a continuous phase and loaded polymer particles as 
a dispersed phase. The loadable polymer particles are those which meet the 
following test. At 25.degree. C., the loadable polymer particles being 
tested must (a) be capable of forming a latex with water at a 
polymer-particle concentration of from 0.2 to 50 percent by weight, 
preferably 1 to 20 percent by weight, based on total weight of the latex, 
and (b) when 100 ml of the latex is then mixed in an equal volume of the 
water-miscible organic solvent to be employed in forming the loaded 
polymeric latex composition, stirred and allowed to stand for 10 minutes 
exhibit no observable coagulation of the polymer particles. Further, the 
latex, after being loaded with the polyaniline, must be able to be 
acidified without exhibiting observable coagulation, again for about 10 
minutes. Useful loadable polymer particles are disclosed by Chen in 
Research Disclosure, No 15930, Vol 159, July, 1977. The entire disclosure 
of this Research Disclosure is hereby incorporated by reference. More 
particularly, useful loadable polymer particles are the cationically 
stabilized polymers of the polymers described in the Research Disclosure 
at page 63, column 2, through pages 67, column 1. 
T. J. Chen has now discovered that certain cationically stabilized 
polyurethane latex polymer particles meet his described loading test. He 
has unexpectedly found that these urethanes form loaded latices which are 
more stable than loaded latices which are made from other conventional 
latices. By "stable" it is meant that the loaded urethanes can be stored 
for long periods, i.e., 30 days or longer, without observable coagulation. 
As a result of this property, hydrophobes which have been difficult to 
load because of crystallization, etc, can now be loaded onto/into these 
urethanes. The discovery that loaded, cationically stabilized 
polyurethanes are surprisingly stable is not our discovery, but is the 
discovery of T. J. Chen made prior to our discovery that cationically 
stabilized latices loaded with polyaniline salt semiconductors form 
coatings with unexpected conductivity. 
Polyurethane latices which can be loaded according to the discovery of Chen 
are polyurethanes derived from a polyol component and an isocyanate 
component. The polyol unit can comprise: 
(a) from 10 to 100 mole percent of one or a mixture of prepolymers having 
two or more than two hydroxy end groups and a molecular weight from 300 to 
20,000, preferably from 500 to 6,000, the recurring units in said polyols 
being lower alkyl ethers or lower alkyl esters; and correspondingly 
(b) 90 to 0 mole percent of a low-molecular-weight diol with or without a 
functionality to impart a positive or a negative charge to the resulting 
polyurethane latex polymer. 
The isocyanate component can comprise one or a mixture of diisocyanates 
conforming to the structure OCNRNCO, wherein R is alkylene, 
alkylene-containing hetero atoms such as oxygen, cycloaliphatic, e.g., 
cyclohexylene, alkylenebiscyclohexylene and isophorone-1,4-diyl, arylene, 
substituted arylene, alkylenebisarylene and arylenebisalkylene. More 
particularly, urethanes which can be loaded according to the discovery of 
Chen to form highly stable latices can be represented by the structure: 
##STR1## 
wherein R is as described above; R.sup.1 is: 
##STR2## 
wherein each Z is independently --O-- or --NH--; R.sup.2, R.sup.3 and 
R.sup.5 are independently selected from alkylene of about 2-10 carbon 
atoms, cycloalkylenebis(oxyalkylene) such as 
1,4-cyclohexylenebis(oxyethylene), arylenebisalkylene such as 
phenylenebismethylene, or the residue of a poly(alkylene oxide) group such 
as -alkylene-O-.sub.p, the alkylene having about 2-4 carbon atoms and p 
being about 2-500; R.sup.4 is an alkylene group of about 2-10 carbon 
atoms; R.sup.6 is alkylene of about 2-10 carbon atoms or arylene such as 
phenylene, naphthylene, bisphenylene, oxydiphenylene and the like; 1 and n 
are independently 2-500; m is 0 or 1; y is 0 to 90 mole percent of the 
diol component of the polyurethane; and z is the total isocyanate 
component of the polyurethane; the ratio of (x+y) to z being about 0.4 to 
1.0. 
A wide variety of polyols and diisocyanates can be used to form stable 
loadable urethanes according to Chen. Appropriate polyols include: (1) 
diols such as alkylenediols of 2-10 carbon atoms, arylenediols such as 
hydroquinone, and polyether diols [HO--CH.sub.2 CH.sub.2 O--.sub.n H]; (2) 
triols such as glycerol, 2-ethyl-2-hydroxymethyl-1,3-propanediol, 
1,1,1-trimethylolpropane and 1,2,6-hexanetriol; (3) tetraols such as 
pentaerylthritol; higher polyols such as sorbitol; and poly(oxyalkylene) 
derivatives of the various polyhydric alcohols mentioned. Other desirable 
polyols include linear polyesters of MW .about.500 with terminal hydroxyl 
groups, low acid numbers and water content; block copolymers of ethylene 
and propylene oxides with a diamine such as ethylenediamine; and 
caprolactam polymers having end hydroxyl groups. Typical diisocyanates 
include 2,4- and 2,6-toluene diisocyanate, 
diphenylmethane-4,4'-diisocyanate, polymethylene polyphenyl isocyanates, 
bitolylene diisocyanate, dianisidine diisocyanate, 1,5-naphthalene 
diisocyanate, 1,6-hexamethylene diisocyanate, 
bis(isocyanatocyclohexylmethane diisocyanate, isophorone diisocyanate, 
2,2,4-(2,4,4)-trimethylhexamethylene diisocyanate, and xylylene 
diisocyanate. 
Polyurethanes which are useful herein are those described above which are 
cationically stabilized. These polyurethanes comprise a polyol unit which 
imparts a positive charge to the polyurethane. Useful polyurethanes which 
are cationically stabilized include those described in U.S. Pat. No. 
3,873,484, the disclosure of which is hereby incorporated by reference. 
Latices of this type are commercially available from the Witco Chemical 
Corp under the designation Witcobond W-210.sup..TM.. 
Other particularly useful cationically stabilized latex polymer dispersion 
which have been loaded with polyaniline salt semiconductor are listed 
below. The number in parentheses after a polymer, here and throughout this 
specification, indicates the weight percentage of the respective monomers 
in the polymer. 
(1) poly(n-butylmethacrylate-co-vinylbenzyl chloride) (90/10) quaternized 
with trimethylamine 
(2) poly[vinyl acetate-co-tetrahydrofurfuryl methacrylate-co-methyl 
methacrylate-co-(N,N,N-trimethyl-N-vinylbenzylammonium chloride)] 
(70/20/5/5) quaternized with trimethylamine 
(3) poly(vinyl acetate-co-methyl methacrylate) (90/10) 
(4) poly[tetrahydrofurfuryl 
methacrylate-co-N,N,N-trimethyl-N-vinylbenzylammonium chloride)] (90/10) 
quaternized with trimethylamine 
(5) poly{methyl acrylate-co-tetrahydrofurfuryl 
methacrylate-co-[2-(methacryloyloxy)ethyl trimethylammonium methosulfate]} 
(35/60/5) 
(6) poly[n-butyl methacrylate-co-butyl acrylate- 
co-(N,N,N-trimethyl-N-vinylbenzylammonium chloride)] (70/20/10) 
quaternized with trimethylamine 
(7) poly(vinyl acetate) 
After the solution of the polyaniline and the dispersion of the loadable 
polymer particles are formed, the two are blended. Generally, it is 
preferred to blend the water-miscible organic solvent solution into the 
dispersion of the loadable polymer particles. Blending is undertaken so 
that the polyaniline remains in solution and the loadable polymer 
particles remain dispersed. 
While blending of water and the loadable polymer particles with the 
water-miscible organic solvent solution of the polyaniline can result in 
significant loading of the polyaniline into the polymer particles, some of 
the polyaniline could still remain in the continuous phase dissolved in 
the water-miscible organic solvent. It is preferred further to load the 
polyaniline into the polymer particles by removing at least a major 
portion of the water-miscible organic solvent. While any of the methods of 
removing the water-miscible organic solvent disclosed in the above-cited 
Research Disclosure of Chen can be used, it is preferred to remove rapidly 
the water-miscible organic solvent by evaporation under reduced pressure. 
The result of these steps is that the loadable polymer particles have 
associated therewith (i.e., loaded) the polyaniline component of the 
semiconductor. 
It is preferred that the loading of the polyaniline take place at a 
substantially neutral pH. The polyaniline-loaded latex may only be stable 
at a pH of 7.0 for about 1-3 wks. However, after acidification to form the 
polyaniline salt-loaded latex, the pH is typically about 2.7. At this pH, 
the coating composition is stable for long periods, i.e., greater than 30 
days. 
It is preferred that the loading of the polyaniline and the subsequent 
acidification of the loaded latex take place in the presence of a 
surfactant. As is known in the art, the surfactant aids in keeping the 
hydrophobic latex polymer particles in suspension. The surfactant is 
typically present at a concentration of about 2 percent by weight of the 
coating composition, although this concentration can be varied depending 
on the particular surfactant, latex, solvent and polyaniline. Preferred 
surfactants are those having an HLB (hydrophilelipophile balance) between 
about 13 and 17. Surfactants meeting this criteria include ethoxylated 
alkyl phenols such as Igepal CO-730.sup..TM., Triton X-102.sup..TM., 
Triton X-165.sup..TM. and Igepal CO-630.sup..TM. ; and block copolymers of 
poly(ethylene oxide) and poly(propylene oxide) such as Pluronic 
L-64.sup..TM. and Pluronic L-44.sup..TM.. 
The weight ratio of the polymer particles to polyaniline in the coating 
composition and therefore the coatings themselves can vary over a wide 
range. It has been found that this ratio has little effect on the 
relationship between resistance of the coating and the coverage of the 
semiconductor. The amount of binder can therefore be chosen to optimize 
the physical properties of the layer and the properties of the coating 
composition to facilitate coating. A useful range of the weight ratio of 
polymer to polyaniline is between about 1:1 and 20:1. Particularly 
desirable layers and coating compositions are formed when this ratio is 
between 4:1 and 10:1. 
The next step in the preferred process is to convert the polyaniline-loaded 
polymer particles to polyaniline salt-loaded particles by acidifying the 
loaded latex dispersion which resulted from the previous step. Acidifying 
of the latex can be accomplished by simply mixing a solution containing 
the appropriate acid with the latex dispersion. The amount and particular 
acid should be chosen so that (a) substantially all of the polyaniline is 
converted to polyaniline salt and (b) the resulting latex is stable for a 
time sufficient to form coatings. Where the acid chosen has the effect of 
destabilizing the latex, the coating composition containing the 
polyaniline salt-loaded latex must be coated immediately. In preferred 
embodiments, however, the latex should be storage-stable. Therefore, the 
acid should be selected so that, when it is mixed with the 
polyaniline-loaded latex, the resulting polyaniline salt-loaded latex is 
stable for at least 10 minutes. The selection of a suitable acid to form 
stable latices depends upon the presence of surfactants, the particular 
loadable polymer particles chosen, the particular polyaniline chosen, the 
pH of the initial polyaniline-loaded latex and other factors. Useful acids 
include halogen acids, e.g., hydrogen chloride, hydrogen bromide, hydrogen 
fluoride, hydrogen iodide, fluoroboric acid and the like; sulfur acids 
such as sulfurous acid, sulfuric acid, thiosulfuric acid, thiocyanic acid 
and the like; acids of phosphorous such as phosphorous acid, phosphoric 
acid and the like; nitrogen acids such as nitrous acid, nitric acid and 
the like. Organic acids including mono-, di- and polyfunctional organic 
acids are also useful. Useful organic acids include aliphatic acids, both 
saturated and unsaturated, having from 1 to about 8 carbon atoms, for 
example, formic, acetic, propionic, maleic and the like; aromatic acids 
such as phthalic, terephthalic, benzoic and the like; and organic 
compounds containing acidic hydrogen atoms such as barbituric acid and 
2-barbituric acid. Preferred acids for forming stable latex dispersions 
include phosphoric acid, nitric acid, and methanesulfonic acid. 
Phosphoric acid forms stable latex dispersions and, in addition, forms 
coatings having exceptional conductivity, even in comparison with similar 
coatings of the invention using other acids. Phosphoric acid is therefore 
particularly preferred. 
As mentioned above, sufficient acid is added to the latex to convert 
substantially all of the polyaniline to polyaniline salt. It can be 
desirable in some circumstances to add excess acid to the 
polyaniline-loaded latex. By "excess" we mean more than a stoichiometric 
amount. Excess acid assures that the latex forms conductive coatings even 
if some of the acid is lost from the coating, such as by leaching. The 
amount of acid added to the polyaniline-loaded latex can therefore vary 
over a wide range. Typically, useful amounts of acid fall within the range 
of 1.0 to 10.0 moles acid/mole imine. Where this ratio is greater than 
about 4:1, an overcoat layer may not properly adhere to the conducting 
layer. Where this ratio is less than about 1.0, the layer may not have 
sufficient conductivity. Because the acid component of the polyaniline 
salt semiconductor can vary over this wide range, it is more accurate to 
describe the coverage in a layer of the semiconductor in terms of the 
coverage of the polyaniline. 
Preparation of the preferred coating composition comprising hydrophobic 
latex polymer particles loaded with polyaniline salt semiconductor has 
been described in detail. Loading in the described manner is the preferred 
method for associating the semiconductor with the latex. It will be 
understood, however, that other methods can be used. For example, the 
semiconductor and the latex polymer can be chosen so that the 
semiconductor is soluble in a monomer which is used to form the latex 
polymer. So long as the polyaniline salt semiconductor is capable of being 
associated with the latex, the coating composition will produce layers 
having unexpectedly high conductivity in comparison with layers made from 
conventional coating compositions. 
The weight percent solids in the latex coating compositions of the present 
invention can vary widely. As is well-known in the art, the percent 
solids, along with the method of coating, has a substantial influence on 
the coverage of the layer that results from the coalescence of the coating 
composition. By "solids" in this context we mean the suspended hydrophobic 
polymer particles including the semiconductor associated therewith. A 
useful range for the weight percent solids in the coating composition is 
between about 0.2 percent and about 15 percent. 
Coating compositions having latex polymer particles having associated 
therewith the semiconductor can be coated on a wide variety of supports to 
form useful conducting elements. The support can be a number of materials 
which can take a number of forms. For example, the coating compositions 
described herein can be coated on polymeric materials such as 
poly(ethylene terephthalate), cellulose acetate, polystyrene, poly(methyl 
methacrylate) and the like. The compositions can also be coated on other 
supports such as glass, paper including resin-coated paper, and metals. 
Fibers, including synthetic fibers, useful for weaving into cloth, can be 
used as the support. Planar supports such as polymeric films useful in 
photography are particularly useful. In addition, the compositions of the 
present invention can be coated onto virtually any article where it is 
desired to have a conductive coating. For example, the compositions can be 
coated on small plastic parts to prevent the unwanted buildup of static 
electricity or coated on small polymeric spheres or other shapes such as 
those used for toners in electrography and the like. 
The compositions of the present invention can be coated onto the support 
using any suitable method. For example, the compositions can be coated by 
spray coating, fluidized bed coating, dip coating, doctor blade coating or 
extrusion hopper coating, to mention but a few. 
A major advantage of the conductive layers of the present invention is that 
they exhibit surprisingly high conductivity at low coverage of the 
semiconductor. By low coverages we mean coverages of about 10 mg/m.sup.2 
or less. Increasing the coverage beyond about 40 mg/m.sup.2 produces 
little increase in conductivity. The exact coverage will depend on the 
particular semiconductor and latex chosen and, of course, the desired 
conductivity. In instances where optical density of the conductive layer 
is not a problem, for example, where the layer is coated on an opaque 
support, high coverages can also be useful. 
The coating compositions of the present invention form useful conductive 
coatings by coalescing the latex having associated therewith the 
semiconductor after the composition has been coated. Typically, 
coalescence occurs by simply allowing the continuous aqueous phase to 
evaporate. In some instances, depending upon the exact nature of the 
polymer particles, it may be necessary to heat the coated composition for 
a short period to coalesce the latex. This is well-known in the art. In 
some cases, improved physical properties result when the coalesced layer 
is cured by heating the layer, such as to about 120.degree. C., for a 
short period, such as for about 30 sec. 
In some embodiments, it may be desirable to coat the layer of the 
compositions of the present invention with a protective layer. The 
protective layer can be present for a variety of reasons. For example, the 
protective layer can be an abrasion-resistant layer or a layer which 
provides other desirable physical properties. In many embodiments, for 
example, it can be desirable to protect the conductive layers of the 
present invention from conditions which could cause the leaching of the 
acid component of the preferred polyaniline salt semiconductor. Where the 
conductive layer of the present invention is part of an element having a 
basic layer, it can be desirable to provide a barrier in the form of a 
protective layer to prevent the contact of the conductive layer by base. 
The protective layer is typically a film-forming polymer which can be 
applied using coating techniques such as those described above for the 
conductive layer itself. Suitable film-forming resins include cellulose 
acetate, cellulose acetate butyrate, poly(methyl methacrylate), 
polyesters, polycarbonates and the like. Currently preferred protective 
layers include layers of poly(n-butyl acrylate-co-styrene), poly(n-butyl 
acrylate-co-methyl methacrylate), poly(n-butyl methacrylate-co-styrene), 
poly(methyl methacrylate) and 
poly(1,4-butylene-1,1,3-trimethyl-3-phenylindan-4',5-dicarboxylate). 
The coating compositions of the present invention are particularly useful 
in forming antistatic layers for photographic elements or conductive 
layers in electrographic and electrophotographic elements. The 
compositions of the present invention can provide high conductivity in 
layers having low coverages and therefore low optical densities. Thus, the 
compositions of the present invention are particularly useful in forming 
antistatic layers for transparent photographic elements such as projection 
transparencies, motion-picture film, microfilm and the like. Elements of 
this type comprise a support having coated thereon at least one 
radiation-sensitive layer. While the conductive layers described herein 
can be in any position in the photographic element, it is preferred that 
the conductive layer be coated on the photographic support on the side of 
the support opposite the side having the coating of the 
radiation-sensitive material. The coating compositions of the present 
invention are advantageously coated directly on the support which can have 
a thin subbing layer as is known in the art, and are then overcoated with 
the described protective layer. Alternatively, the conductive layers of 
the present invention can be on the same side of the support as the 
radiation-sensitive materials and the protective layers can be included as 
interlayers or overcoats, if desired. 
The radiation-sensitive layers of the photographic or electrophotographic 
elements of the present invention can take a wide variety of forms. The 
layers can comprise photographic silver salt emulsions, such as silver 
halide emulsions; diazo-type compositions; vesicular image-forming 
compositions; photopolymerizable compositions; electrophotographic 
compositions comprising radiation-sensitive semiconductors; and the like. 
Photographic silver halide emulsions are particularly preferred and are 
described for example, in Product Licensing Index, Publication 9232, Vol. 
92, December, 1971, pages 107-110. 
Another particularly useful element is an electrographic element. The 
conductive layers of the present invention, because of the uniformity of 
their conductivity and the humidity independence of their conductivity, 
are excellent conductive layers for such an element. This embodiment of 
the present invention comprises a support having coated thereon the 
conductive layer as described herein and, as the outermost layer, a 
dielectric layer. In this embodiment, the conductive layer can have some 
density so that high coverages of polyaniline, such as about 35 mg/m.sup.2 
can be used so that the resulting conductive layer can have very high 
conductivity. Higher or lower coverages can also be used. The dielectric 
layer can be formed from any dielectric film-forming material such as any 
of the polymers listed above as useful as the protective layer. The 
currently preferred dielectric layer for this embodiment is 
poly(ethylene-co-4,4'-isopropylidene bisphenoxyethyl terephthalate) which 
is described in U.S. Pat. No. 3,703,372. Optionally, and in preferred 
embodiments, the dielectric layer further comprises a matting agent. 
Numerous matting agents can be used such as poly(methyl methacrylate) 
beads described in U.S. Pat. Nos. 2,701,245 and 3,810,759. The currently 
preferred matting agent is beads of polyethylene, along with some 
fluorocarbon such as Polyfluo.TM. #190 beads available from Micro Powders, 
Inc., of Yonkers, N.Y. This type of matting agent is preferred because it 
does not swell in the solvents used, thereby preventing bead agglomeration 
which degrades image quality. The use of electrographic elements of the 
type described is well-known and is described, for example, by Dessauer 
and Clark, Xerography and Related Processes, Focal Press, 1965, Chapter 
XVI, pp 439-450. 
The resistance of the surface of the coatings of the present invention can 
be measured using well-known techniques. The resistivity is the electrical 
resistance of a square of a thin film of material measured in the plane of 
the material between opposite sides. This is described more fully in R. E. 
Atchison, Aust. J. Appl. Sci. 10 (1954). 
The coverage of the imine component of the preferred conductive layer of 
the present invention can be readily calculated using known methods.

The following examples are presented to illustrate the practice of the 
invention and are not intended to limit the invention in any way. 
EXAMPLE 1 
(A) Preparation of a Polyaniline Salt-Loaded Polymer Latex 
A 28.4-g portion of a 35.2% by weight solid dispersion of Witco Bond 
W-210.TM. was diluted to a total weight of 400 g with water. To this was 
added a solution of 2.0 g of 
N-{p-[4-(p-methoxyanilino)anilino]phenyl}-1,4-benzoquinone imine in 100 mL 
of acetone. The acetone was then removed by rotary evaporation, forming a 
polyaniline-loaded polymer dispersion of the Witco Bond W-210.TM. latex. 
To 393 g of the polyaniline-loaded latex were added 500 g of water, 14 mL 
of 10% phosphoric acid, and then additional water to total weight of 1,180 
g. The resulting dispersion is a polyaniline salt-loaded latex. 
(B) Preparation of a Conductive Coating 
The polyaniline salt dispersion described above was coated onto a subbed 
polyester support at a wet coverage of 10.8 mL/m.sup.2. The water of the 
latex dispersion was removed by evaporation with a moderate amount of heat 
to give a coalesced film having an electrical resistivity of 
2.times.10.sup.6 ohm/sq and a dry coverage of the imine component of the 
layer of 17 mg/m.sup.2 of support. The integrated optical density of 
support between 400 and 700 nm was 0.015. 
EXAMPLE 2 
A 100-g portion of the polyaniline salt-loaded latex prepared in Example 1 
was diluted with water to a total weight of 333 g and coated at a rate of 
8.6 mL/m.sup.2 onto a subbed polyester support. The water was removed by 
evaporation to give a coalesced film having a surface electrical 
resistivity of 5.times.10.sup.7 ohm/sq and a dry coverage of the 
polyaniline component of 4.3 mg/m.sup.2 of support. 
EXAMPLE 3 
A 107-g portion of the polyaniline-loaded latex dispersion prepared as in 
Example 1 was diluted with water to a total weight of 400 g. To this 
dispersion was added 3.65 mL of a 10% solution of methanesulfonic acid. 
The resulting polyaniline salt-loaded latex was coated onto a subbed 
polyester support and the water removed by evaporation. The resulting 
coalesced film had a surface electrical resistivity of 1.1.times.10.sup.7 
ohm/sq and a dry coverage of polyaniline component of 17 mg/m.sup.2 of 
support. 
EXAMPLE 4 
A polyaniline-loaded latex was formed as in Example 1, except that the 
imine chosen was N-{p-[p-(anilino)anilino]phenyl}-1,4-benzoquinone 
diimine. An 80-g portion of this polyaniline-loaded polymer dispersion was 
diluted to a weight of 340 g with water, and 2.70 mL of a 10% solution of 
phosphoric acid was added. The resulting polyaniline salt-loaded latex 
dispersion was coated onto a subbed polyester support. The water of the 
latex was removed by evaporation to give a coalesced film having a surface 
electrical resistivity of 9.3.times.10.sup.6 ohm/sq and a dry coverage of 
the polyaniline component of 17 mg/ft.sup.2 of support. 
EXAMPLE 5 
(A) Preparation of a Polyaniline Salt-Loaded Latex 
30.39 g of a 16.45% solids latex of poly(n-butyl 
methacrylate-co-vinylbenzyl chloride) (90/10) quaternized with 
trimethylamine was added 0.10 g of Igepal CO-730.TM. Surfactant, as a 
dispersing aid, and water to give a total weight of 200 g. To this latex 
was added a solution of 1.0 g of the polyaniline of Example 1 in 55 mL of 
acetone. The acetone was removed by rotary evaporation to produce a 
polyaniline-loaded latex. To 1.7 g of the imine-loaded latex dispersion 
were added 200 g of water, 3.8 mL of a 10% solution of phosphoric acid, 
and additional water for a total weight of 400 g. The result was a 
polyaniline salt-loaded latex. 
(B) Coating of the Polyaniline Salt-Loaded Latex 
The latex from step (A) was coated onto a subbed polyester support at a 
coverage of 10.8 mL/m.sup.2. The water was removed by evaporation to give 
a coalesced film having a surface electrical resistivity of 
5.times.10.sup.6 ohm/sq and a dry coverage of the polyaniline component of 
17 mg/m.sup.2 of support. The integrated optical density in the 400-700 nm 
region was 0.015. 
EXAMPLE 6 
This is a comparative example. 
A polyaniline salt-loaded latex was prepared according to the procedures 
set forth in Example 1. The latex used was a 5% by weight latex of 
poly(n-butyl acrylate-co-2-acrylamido-2-methylpropanesulfonic acid) 
(90/10), an anionically stabilized latex. The polyaniline was 
N-{p-[4-(p-methoxyanilino)anilino]phenyl}-1,4-benzoquinone imine which was 
introduced into the latex using a 0.5% by weight solution of the imine in 
acetone. To 40 g of this polyaniline-loaded latex were added 7.3 mL of a 
2% phosphoric acid solution in water to form the polyaniline salt-loaded 
latex. This latex was coated onto a subbed polyester support and the water 
was removed by evaporation to give a coalesced film. The film had an 
electrical resistivity of 2.0.times.10.sup.9 ohm/sq and a coverage of the 
polyaniline component of 16 mg/m.sup.2. 
EXAMPLE 7 
This is a comparative example. 
A conductive coating was prepared using the polyaniline salt of Example 1 
in a gelatin binder in the following manner: An amount of 400 mL of a 1% 
by weight gelatin solution was warmed to 40.degree. C. and 4.0 mL of a 
solution containing 1% by weight Olin 10G.TM. surfactant and 0.76 g of 85% 
phosphoric acid were added. Then 25 mL of a solution containing 0.8 g of 
the polyaniline of Example 1 in acetone were added to the gelatin solution 
with strong agitation. The acetone was removed by rotary evaporation 
leaving a finely divided dispersion of the polyaniline salt in the gelatin 
solution. The polyaniline salt was not associated with the gelatin. This 
dispersion was coated on a suitable polyester support so as to produce a 
coverage of the polyaniline of about 28.6 mg/m.sup.2 of support. After 
drying, the layer had a resistivity of 5.3.times.10.sup.8 ohm/sq. This 
example illustrates that conventional layers of polyaniline salt 
semiconductors, even when the semiconductor is coated at almost twice the 
coverage, do not exhibit the high conductivity of the layers of the 
present invention. Compare Example 1's coverage of 17 mg/m.sup.2 and 
resistivity of 2.times.10.sup.6 ohm/sq with comparative Example 7's 
coverage of 28.6 mg/m.sup.2 and resistivity of 5.3.times.10.sup.8 ohm/sq. 
EXAMPLE 8 
This is a comparative example. 
A conductive coating was prepared using the polyaniline salt of Example 1 
and the latex binder of Example 1, except that the polyaniline salt was 
not associated with the latex before coating and coalescing. The 
conductive layer was prepared in the following manner: To 180 mL of water 
containing 6.2 mL of 10% phosphoric acid and 0.1 g of Igepal CO-730.TM. 
surfactant were added 25 mL of an acetone solution containing 1.05 g of 
the polyaniline of Example 1 and 0.1 g of Igepal CO-630.TM.. The addition 
was made with strong agitation. The acetone was removed from the resulting 
solution, resulting in a finely divided dispersion of the polyaniline salt 
semiconductor in water. To this dispersion were added 14.2 g of a 35% by 
weight solids dispersion of Witco Bond W-210.TM. latex. Under those 
conditions, no noticeable amount of semiconductor became associated with 
the latex; rather, a codispersion of semiconductor and latex was formed. 
This codispersion was coated on subbed polyester support and dried to form 
a coalesced layer having polyaniline coverage of 10.8 mg/m.sup.2 of 
support. This layer had a resistivity of 3.8.times.10.sup.7. A layer 
coated from the loaded latex described in Example 1 was coated at the same 
coverage and had a resistivity of 3.5.times.10.sup.6. When this comparison 
was repeated at a coverage of polyaniline of 5.4 mg/m.sup.2, resistance of 
the coating made from codispersion was 4.3.times.10.sup.8 ohm/sq, more 
than an order of magnitude increase, while the coating made from the 
loaded latex increased by less than a factor of two to 6.3.times.10.sup.6 
ohm/sq. 
EXAMPLES 9-12 
These are comparative examples. 
In a manner similar to Example 8, coatings were made from codispersions and 
from coating compositions of the present invention using various 
polyanilines and acids. 
Codispersion preparations (identified a and c) 
A solution of 1.0 g of the polyaniline and 0.1 g of Igepal CO-630.TM. 
surfactant in 55 mL of acetone were added to 200 mL of a strongly 
agitated, aqueous solution containing 0.2 g Igepal 730.TM. surfactant and 
sufficient acid to produce a ratio of 2.5 moles acid/mole polyaniline. The 
acetone was removed from the resulting solution to produce a dispersion of 
polyaniline salt in water. To this dispersion were added 5.0 g of latex 
polymer (Witcobond W-210.TM.) solids to form a codispersion of polyaniline 
salt and latex polymer. 
Loaded latex preparation (identified b and d): 
Latices loaded with polyaniline salt were prepared in a manner similar to 
Example 1. 
Both the loaded latex of the invention and the codispersion were coated at 
coverages of 10.8 and 5.4 mg polyaniline/m.sup.2. The results are shown in 
table 1. 
EXAMPLES 13-19 
Example 1 was repeated, substituting various cationically stabilized latex 
polymers for Witcobond W-210.TM.. In each case, the weight ratio of latex 
polymer/polyaniline was 5:1. The results are shown in Table 1. The numbers 
for the polymers are given above in the discussion of useful loadable 
polymers. 
The following table reproduces pertinent data from the above examples. 
Where appropriate, the designation for the polyaniline and for the binder 
corresponds to the designation given these components above. 
TABLE 1 
__________________________________________________________________________ 
Coverage 
Resistivity 
Example 
Polyaniline 
Acid Binder 
mg/m.sup.2 
ohm/sq 
Comment 
__________________________________________________________________________ 
1 (a) phosphoric 
W-210 
17 2 .times. 10.sup.6 
2 (a) phosphoric 
W-210 
4.3 5 .times. 10.sup.7 
3 (a) methane 
W-210 
17 1.1 .times. 10.sup.7 
sulfonic 
4 (b) methane 
W-210 
17 9.3 .times. 10.sup.6 
sulfonic 
5 (a) phosphoric 
(1) 17 5 .times. 10.sup.6 
6 (a) phosphoric 
cationic 
16 2.0 .times. 10.sup.9 
comparative 
latex 
7 (a) phosphoric 
gelatin 
28.6 5.3 .times. 10.sup.8 
comparative 
8a (a) phosphoric 
W-210 
10.8 3.8 .times. 10.sup.7 
comparative codispersion 
8b (a) phosphoric 
W-210 
10.8 3.5 .times. 10.sup.6 
8c (a) phosphoric 
W-210 
5.4 4.3 .times. 10.sup.8 
comparative codispersion 
8d (a) phosphoric 
W-210 
5.4 6.3 .times. 10.sup.6 
9a (a) methane 
W-210 
10.8 2.7 .times. 10.sup.6 
comparative codispersion 
sulfonic 
9b (a) methane 
W-210 
10.8 1.8 .times. 10.sup.6 
sulfonic 
9c (a) methane 
W-210 
5.4 1.0 .times. 10.sup.7 
comparative codispersion 
sulfonic 
9d (a) methane 
W-210 
5.4 4.2 .times. 10.sup.6 
sulfonic 
10a (a) nitric 
W-210 
10.8 &gt;10.sup.12 
comparative codispersion 
10b (a) nitric 
W-210 
10.8 4.6 .times. 10.sup.6 
10c (a) nitric 
W-210 
5.4 &gt;10.sup.12 
comparative codispersion 
10d (a) nitric 
W-210 
5.4 2.6 .times. 10.sup.7 
11a (b) phosphoric 
W-210 
10.8 &gt;10.sup.12 
comparative codispersion 
11b (b) phosphoric 
W-210 
10.8 7.0 .times. 10.sup.6 
11c (b) phosphoric 
W-210 
5.4 &gt;10.sup.12 
comparative codispersion 
11d (b) phosphoric 
W-210 
5.4 2.5 .times. 10.sup.7 
12a (c) phosphoric 
W-210 
10.8 1.7 .times. 10.sup.8 
comparative codispersion 
12b (c) phosphoric 
W-210 
10.8 4.5 .times. 10.sup.6 
12c (c) phosphoric 
W-210 
5.4 8.3 .times. 10.sup.8 
comparative codispersion 
12d (c) phosphoric 
W-210 
5.4 1.3 .times. 10.sup.7 
13 (a) phosphoric 
2 10.8 5.0 .times.10.sup.6 
14 (a) phosphoric 
1 10.8 4.4 .times. 10.sup.6 
15 (a) phosphoric 
3 10.8 3 .times. 10.sup.6 
16 (a) phosphoric 
4 10.8 1.1 .times. 10.sup.7 
17 (a) phosphoric 
5 10.8 5 .times. 10.sup.6 
18 (a) phosphoric 
6 10.8 4.2 .times. 10.sup.6 
19 (a) phosphoric 
7 10.8 3.6 .times. 10.sup.6 
__________________________________________________________________________ 
EXAMPLE 20 
An electrographic element was prepared by coating a conductive layer on a 
subbed poly(ethylene terephthalate) film support and then overcoating the 
conductive layer with a dielectric layer. The conductive layer was coated 
using the coating composition described in Example 1, wherein the weight 
ratio of latex to polyaniline was 5:1, so as to produce a coverage of 
polyaniline salt of about 30 mg/m.sup.2. The dielectric layer was a 
3.5-micron layer of poly(ethylene-co-4,4'-isopropylidene bisphenoxyethyl 
terephthalate) (50:50) containing 3.5 weight percent Polyfluo.TM. #190 
matt beads. A spreading agent as described in U.S. Pat. No. 3,861,915 was 
used in coating the dielectric layer. 
The described electrographic element was imaged on a Gould #5005 
Plotter/Printer stylus recording device and toned with a liquid 
electroscopic developer. Image quality was excellent. 
The invention has been described in detail with particular reference to 
preferred embodiments, but it will be understood that variations and 
modifications can be effected without departing from the spirit and scope 
of the invention.