Note: Descriptions are shown in the official language in which they were submitted.
` ~ 1327416
, ,.
Description
.:~
Electroconductive coating composition, a process for the
production thereof and the use thereof.
The invention re(ates to an electroconductive coating
composition ~hich is capable of preventing electrostatic
charge on surfaces, to a process for the production there-
;; of, and to the use thereof.
For reasons of safety at work, such as, for example,
explosion protection, packages made from highly insula-
ting plast;cs must usually be provided ~ith an anti-
static finish. In this field, transparent conductive
~- films are particularly desired since identification of
;- the contents is possible.
~; 15
In other uses too, the high electrostatic chargeability
of customary plastics results in difficulties:
'~1! - Poor ~ind-up behavior of calendered films and fast-
q ness.
- Z0 - Mutual adhesion of film sheets during processing and
i,; in filling plants.
- Sparking during emptying of plastic containers in the
presence of explosive gas/air mixtures (for example
solvents) can result in dangerous explosions.
- The printability of plastic parts is destroyed.
:..
- - Plastic parts attract dust during storage and become
soil~d.
- In the case of packaging of sensitive electronic com-
ponents, the latter are destroyed by electrostatic
` 30 charge on packing.
- Photographic films and X-ray films can be rendered
unusable by electrostatic charge due to so-called
"static marking".
There are several ~ays of dissipating charges on the
.' ~
.
:.
.: ~ ': .,,
, . ..
- 2 - 1327416
~ plastic surface:
:
a) Compounds made from plastics and carbon black or a
metal powder or metal fibres. Since they only become
- 5 active when the conductive particles come into con-
tact (perco~ation), large added amounts o~ conductive
material are necessary (typically 5% to 30%). The
typical property profile of the plastic is thereby
considerably modified, its mechanical propert;es
become markedLy uorse and the optical propert;es,
such as transparency and color, are totally changed.
"
b) In many plastics, the surfaces can be modified by an
; intensive corona discharge until electrostatic charge
no longer occurs. Unfortunately, the action diminishes
after a short time, meaning that this method cannot
be used for long-term application and is often em-
ployed only to improve the coatability.
. ~
; 2Q c) Conductive surfaces are produced by adding anti-
statics to the plastic surface, for example by dip-
ping, soaking or spraying. However, these antistatics
can also be incorporated into the plastic mass, and a
long-term action is achieved. In both cases, it ;s a
~ 25 great disadvantage that the surface resistance of the
`~~ plastics treated in this way is greatly dependent on
atmospheric moisture; their etfectiveness decreases
rapidly, in particular when the materials are exposed
to very low humidity.
; d) Plastics can be coated with vapor-deposited metals
or inorganic semiconductors in vacuo or by sputter-
ing. These metal coatings must be applied very thinly
; if adequate transparency is required. As a conse-
- 35 quence, these coatings are very sensitive and would
. have to be protected, by additional coatings, against
mechanical and chemical damage~ This process is com-
plicated, involved and expensive. In addition, the
choice of usable materials is limited by susceptibility
. , ,
:
.,
' '~ '' ' ~'' ' ' ' '.'
; , .
:
,
1327416
- - 3 -
to corrosion. In addition, metaL coatings vapor-
deposited on plastic films often exhibit poor coat-
`~ ing adhesion, and it is necessary to improve this
by additional process steps, such as, for example,
the abovementioned corona treatment. In these multi-
layer film systems, the metal coating is also pro-
tected by a dielectric coating against external mech-
anical damage; the thickness of this dielectric coat-
ing must itself be observed very accurately in order
to achieve the surface resistance desired. Together
with a customary antistatic coating on the inside of
the film, a storage effect for the electrical charges
can occurt due to which the prevention of electro-
~`i static charges is achieved only unsa~isfactorily.
Such products are therefore only suitable for screen-
ing against externaL fields (Faraday cage).
~ ;,
, i,.f .
The object of the present invention is therefore to pro-
3`' duce electroconductive coatings which do not have the
abovementioned disadvantages and, in addition, can be
applied to any desired surfaces.
.,~
It has been found that a coating composition comprising
; a soluble oligomer of substituted thiophenes and a
soluble poLymer can produce a highly adherent electro-
conductive coating on various substrates.
The invention thus relates to an electroconductive coat-
ing composition comprising 10 to 100% by weight of an
oligomer having three to ten structural units which are
connected to one another by linkage in the two-position
- andlor five-position, on statistical average comprising
60 to 100% by weight of structural units derived from
at least one monomer of the formula (~)
R1 R2
H (I),
in which
,,
';.
. ,, - .. . .. . .
,, ; . . . ~ . .
2741 ~
: - 4 -
R1 denotes a C1-C12 alkoxy group or -O(CHn2CH20)nCH3
where n = 1 to 4 and
R2 denotes a hydrogen atom, a C1-C12 alkyl group,
a C1-C12-alkoxy group or -O(CH2CH20)nCH3 where
n = 1 to 4, or
R1 together with R2 represents -O(CHz)m-CH2- or
~^ -O(CH2)m-0-, in which m is 1 to 12,
0 to 40X by ~eight of structural units derived from at
.~ least one monomer of the formula (II)
~ ~ 6 (II),
``:
in which R4 and R5, independently of one another,
denote a hydrogen atom, a halogen atom, a C1-C12-
alkyl group or aryl or, together with the carbon atoms
: linking them, form an aromatic r;ng,
R3 and R6, independently of one another, denote a
hydrogen atom, or R3 together with R4 and the carbon
atoms linking them, or RS together with R6 together
. with the carbon atoms linking them, ;n each case form an
~ aromatic ring,
.. 20 X denotes an oxygen atom, a sulfur atom, an =NH group,
,;
~i an =N-alkyl group or an =N-aryl group,
:~ 0 to 40~ by weight of structural units derived from at
least one monomer of formula (III)
R7 RE1 R9 R10
i ,~¢ ~3~ ( I I I ),
.. H Y Z H
in which R7, R8, R9 and R10 independently of one
another denote a hydrogen atom, a C1-C12 alkyl
group, a C1-C12-alkoxy group or an aryl group,
::. Y and Z, independently of one another, denote an oxygen
atom, a sulfur atom, an =NH group, an =N-alkyl group or
an =N-aryl group,
R11 denotes an arylene group, a heteroarylene group or a
conjugated system of the formula -(-CH=CH)-o, in which o
:
.:
. ,,
.. . .
;,~; - : .
-
.
, ~
, ~ .
,
-- 1327416
- 5 -
is zero, 1, 2 or 3,
0 to 40% by ~eight of structural units derived from at
least one monomer of the formula (IV)
R12 R13 (IV),
in which R12 and R13, independently of one another,
denote a hydrogen atom, a halogen atom, a C1-C12-alkyl
group, a C1-C12-alkoxy group, a C1-C4-alkylamino group
s or a C1-C4-acylamino group,
sJ R14 denotes a halogen atom, a C1-C12-alkyl group, a C1-C12-
alkoxy group, a C1-C4-alkylamino group or a C1-C4-acylamino
group and X has the abovementioned meaning,
where the oligomer, in the oxidized form, is completely
soluble in dipolar aprotic solvents at 25C, and solu-
tions having a content of at least 0.5 9 of the oligomer
in 100 mL of solvent are obtained at Z5C, and
0 to 90% by weight of a polymer ~hich ;s dissolved or
swollen in solvents or solvent mixtures hav;ng aCp value
greater than 3.5 (cal/ccm)1/2 and a ~H value less than
~' 6.5 (cal/ccm)1~2.
In addition, the invention also relates to a proces for
the production of the coating composition mentoned wherein
oligomer and, where appropriate, polymer are dissolved or
-~ swollen together in a solvent or solvent mixture having a
Cp value greater than 3.5 (cal/ ccm)1/2 and ac H value
less than 6.5 (cal/ccm)1/2, and the mixture is recovered
from the solvent.
,::
Finally, the invention relates to the use of this coating
composition for the production of electroconductive coatings
on nonconductive or semiconductive materials.
,
; The coating composition according to the invention com-
prises an oligomer and, where appropriate, a polymer.
The oligomer contains structural units which are
'~'
,
'',
,
, ,. ~ - . . .
'''' . ~ - . ~, :' .
,'~ .
- 6 - 1 3 2 7 4 1 ~
derived, by linking in the 2-position and/or 5-pos;tion,
from at least one monomer of the formula (I)
:`~
.,.~ Rl R2
in which H ~ ~ (I),
R1 denotes a C1-C12-, preferably C1-C4-, in particular C1-
C2-alkoxy group or -O~CH2CH20)nCH3 where n = 1 to 4, pre-
ferably 1 or 2, and
R2 denotes a hydrogen atom, a C1-C1z-, preferably C1-C4-
alkoxy group, in particular a C1-C2-alkoxy group, a C1-
10 C12-, preferably C1-C4-alkyl group, or -O(CH2CH20)nCH3
where n = 1 to 4, preferably 1 or 2, or R1 toge~her with
R2 represents -O(CH2)m-CH2- or -O(CH2)m-0- where m = 1
to 12, preferably 1 to 4~
. ,~
ExampLes of representatives of the formula (I) are
3-Methoxythiophene, 3-ethoxythiophene, 3-propoxythiophene,
3-methoxy-4-methylthiophene, 3-methoxy-4-ethylthiophene,
3-methoxy-4-butylthiophene, 3-ethoxy-4-methylthiophene,
3-ethoxy-4-ethylthiophene, 3,4-dimethoxythiophene, 3-
1 20 ethoxy-4-methoxythiophene, 3-butoxy-4-methoxythiophene,
3-(methoxyethoxy)thiophene, 3-(methoxyethoxyethoxy)-
thiophene, 3,4-(ethylene-1,2-dioxy)thiophene and 3,4-
tprop-3-ylene-1-oxy)thiophene. It is also possible to
~- employ mixtures of monomers (I).
Suitable comonomers for the monomers (I) are all aroma-
tic and heteroaromatic compounds which are capable of
' ~!
, forming electroconduçtive polymers and with which the
monomers (I) can be copolymerized. Examples which may be
~ 30 mentioned here are compounds of the formula (II)
:,
R4 R5 ~II).
; R X R6 --
R4 and R5, independently of one another, are a
hydrogen atom, a halogen atom, a C1-C12-, preferably
C1-C4-alkyl group, or an aryl group, preferab~y
. . .
?.
:,', ' . ' . ', '
.: ;,, ~ :
'.',' ' ' ' ' ' '
. ~ . .
'~' ' . '
. '~ . .
: . .
1327416
- 7
phe,1yl or thienyl, or, together with the carbon atoms
bonding them, form an aromatic ring, preferably a ben-
zene, thiophene or pyrrole ring.
S R3 and R6, independently of one another, are a
hydrogen atom or, in each case with R4 or R5 and
together with the carbon atoms bonding them, form an
aromatic ring, preferably a benzene, thiophene or
pyrrole ring.
X denotes an oxygen atom, a sulfur atom, an =NH group,
an =N-alkyl group, preferably =N-C1-C4-alkyl, or
; N-aryl, preferably N-phenyl.
-~ 15 Pyrrole, 3-chloropyrrole, 3-methylpyrrole, 3,4-dimethyL-
pyrrole, N-methyLpyrroLe, thienoC3,2-b]pyrrole, carba-
`~l zole, thiophene, 3-methylthiophene, 3-octylthiophene,
3,4-dimethylthiophene, 3,4-diethylthiophene, isoth;a-
naphthene and thienoC2,3-b~thiophene, diethienoC3,2-b;
20 2',3'-d]thiophene, and dibenzothiophene,preferably
pyrrole and 3-methylthiophene, are suitable.
.
i Further suitable comonomers for monomers (I) are those of
3 the formula (III):
ZS Rll ~ ~ (III),
R7, R8, R9 and R10, ;ndependently of one another, are a
hydrogen atom, a C1-C12-, preferably C1-C4-alkyl group,
a C1-C12-alkoxy group, preferably C1-C4 alkoxy, or an
aryl group, prefsrably phenyl or thienyl. Y and Z, inde-
pendently of one another, denote an oxygen atom, a sulfur
atom, an =NH group, an =N-alkyl group, preferably =N-C1-
C4-alkyL, or an =N-aryL group, preferabLy =N-phenyL. R
represents aryLene, preferabLy phenylene, heteroarylene,
preferably th;enylene, furanylene, pyrrolylene or a con-
~ jugated system of the formula
:,
. ~ .
j, '
: , ' ' , .
.: .
1327~16
~ - 8 -
i . ...
~ C~ = CH ~
,
where o = 0, 1, 2 or 3.
';
~ In particular, 1,2-di~2-thienyl)ethene, 1,2-di(3-methyl-
;~ 5 thien-2-yl)ethene, 1,2-di(2-furanyl)ethene, 1-(Z-
furanyl)-2-~2-thienyl)ethene, 1-(2-pyrrolyl)-2-(2-
~ thienyl)ethene, 1,4-di(2-thienyl)buta-1,3-diene, 1,4-
;~ di(2-furanyl)buta-1,3-diene, 1,4-di(2-thienyl)benzene,
i terthienyl(2,5-di(2-thienyl)thiophcne), 2,5-di(2-
`~ 10 thienyl)pyrrole, 2,2'-bithiophene, 3,3'-dimethyl-2,2'-
bithiophene, 3,3'-dimethoxy-2,2'-bithiophene, 3,4'-di-
, .,
methoxy-2,2'-bithiophene and 4,4'-dimethoxy-Z,Z'-bi-
thiophene are suitable.
The abovementioned comonomers (II) and (III) can aLso be
-I used mixed with one another. The preparation of the com-
~ pounds (II) and (III) is known from the prior art.
,l,,,j
The oligomers contain three to ten structural units,
preferably four ~o nine structural units and in particu-
lar five or six structural units. The amount of these
structural units derived from at Least one monomer of
the formula (I) is on statistical average 60 to 100% by
~ ~eight, preterably 90 to 100X by ~eight and in particu-
-~ 25 lar 95 to 100Z by ~eight, relative to the structural
,.,~
l units present in the undoped oligomer.
,; The amount of structural units derived from monomers of
the formula (II) iS, on statistical average 0 to 40~
~; 30 preferably 0 to 10X by ueight, and the structural units
derived from monomers of the formula (III) are present
.,,`:,!,
~ on statistical average to the extent of 0 to 40, pre-
- ferably 0 to 10X by weight.
.~, .
.:,
In addition, the terminal groups of the oligomers can be
formed from structural units of monomers (IV) ~hich can
be added to the monomers of the generaL formuLa (I) in
. i,~,.,
. .,
. ~ ~
," ~:.
.. . .
.~ -
, .
. ,~, ,
:.' '.
. , :
` ~ - 9 - 1~27416
order to ~odify the degree of poLymerization and the
physical properties.
:
R12 Rl~l
~ ( IV),
X R1'1
, .
,
; R12 and R13, independently of one another, are a
, 5 hydrogen atom, a halogen atom, preferably chlorine or
bromine, a C1-C12, preferably C1-C4-alkyl group, a C1-
~, C12, preferably C1-C4-alkoxy group, a C1-C4 alkylamino
group or a C1-C4-acylamino group, preferably acetyl-
amino.
~ 10
`- R14 is a halogen atom, a C1-C12-, preferably C1-C4-alkyl
, group, a C1-C12-, preferably C1-C4-alkoxy group, a C1-C4-
ii alkylamino group or a C1-C4-acylamino group, preferably
. acetyl amino.
X has the abovementioned meaning.
¦ Examples of the compounds of formula (IV) are 2-methoxy-~ th;ophene, 2-methylthiophene, 2-bromothiophene, 2-
- chlorothiophene, 2-acetylam;noth;ophene, 2-bromo-3-
methoxyth;ophene, 2-bromo-4-methoxythiophene, 2-chloro-
3-methylthiophene, 2,3-d;methoxythiophene, 2,4-dimethoxy-
thiophene, 2,3-dimethylthiophene, 3-methoxy-2-methyl-
thiophene, 2-methoxy-3-methylthiophene and 4-methoxy-2-
methylthiophene, 2-chloro-4-methoxythiophene, 2-acetyl-
amino-3-methoxythiophene, 2-methylpyrrole, 2-bromopyrrole,
2-chloropyrroLe, 2-methylfuran and 2-methoxyfuran. As a
; consequence of the substitution in the 2-position, these
compounds have a chain terminating action. The amount of
j (IV) is generally û to 4ûX by ~eight, preferably less
-~` 30 than 1û% by ueight and in particular less than 5~ by
~eight, relative to the total amount of monomers.
. ,.
., ,:
. The soluble, electroconduct;ve oligomers contain, in the
oxidized form, an appropriate number of anions ;n order
,~ .
.. . . .
, . ~,
. - . - ~ -, , .
'5i, ' ' , , , ' ' ' ' , ` .
~ . ~ . ' ' ' ' ' ' ' "
',', ' .': , ,
.,:, ~ , . :
--` - 10 1327416
to compensate-for the positive charges. These are pre-
ferably anions of the conductive salt ~hich ~as employed
in the preparation process Exa~ples of suitable anions
~ ~hich may be mentioned here are ~F4 , PF6 , SbF6 ,
; 5 SbCl6 , FeCl4 , FeC(CN)6~3 , F , Cl , ~r , SCN , S042-,
HS04 _, P043-, alkyl-S03 _, perfluoroalkyl-503 , aryl-S03 ,
alkyl-C02 , perfluoroaLkyl-C02 , aryl-C02 and phenolate
~ith loss of thermal stability, ClO4 , and N03 are also
suitable ~F4 , PF6 and CF3503 , are preferred It is
also possible for mixtures of the above~entioned anions
; incorporated into the oligomer to be present The number
of these anions, relative to the number ot monomer units,
is usualLy 10 to 30X, preferably 15 to 20X
-' 15 The oligomer and its preparation are the sub~ect-matter
of European patent application EP-A-257 573.
(
The poly~er which, if ~ppropriate, is like~ise present
in the coating composition according to the invention
-I 20 should be soluble or swellable in solvents or solvent
mixtures having a ~p value (deltap value) greater
than 3.5, preferably greater than 5.5 (cal/ccm)1/2 and
a ~H value (deltaH value) less than 6.5, preferably less
than 5 0 (cal/ccm)1/2
:.,,
Suitable polymers ~re poly(vinyl acetal), poly(vinyl
acetate), poly(maleic anhydride), poly-N-vinylpyrrol-
idone), poly(4-vinylpyridine), poly(methyl methacryl-
ate), poly(ethyl ~ethacrylate), polyacroleine, polyform-
aldehyde, poly(ethylene oxide), polytpropylene oxide),cellulose acetate, styr-ne-~crylonitrile eopoly~ers,
polyacrylonitril~, Poly~-th-crylonitril~, poly~vinyl
chlorid-), poly(vinylid~ne fluoride), poly-N-vinylcar-
bazole, poly-N-vinylacet~mide, poly~acrylic anhydride),
- 35 poly(ethylen- carbon~te), poly-E-caprolacta~ and further
polymer~ or copoly~ers.
Poly(methyl methacrylate), styrene-acrylonitrile eopoly-
mers and poly(vinyl acetal) are preferred
,^ . s -
:.,,
,.:
,,., ' , ~ .
. .
::
.
: ~
1327416
~esides the oligomer and, if appropriate, the polymer,
the coating composition according to the invention can
contain further additives, such as, for example, stabi-
lizers, plasticizers, pigments, dulling agents, lubri-
cants and other additives.
, .
The coating composition contains 10 to 100, preferably
30 to 90% by weight, relative to the total amount, of
oligomer and 0 to 90, preferably 10 to 70, % by weight,
relative to the total amount, of polymer. Further addi-
tives are added in addition, if necessary.
The solvents or swelling agents used for the oligomer
;~ and the polymer are dipolar aprotic solvents having a
~p value greater than 3.5, preferably greater than 5.5
(cal/ccm)1/2 and a~ H value less than 6.5, preferably
less than 5.0 ~cal/ccm)1/2. The ~ values are listed in
A.F. Barton, Handbook of Solubility Parameters and other
i Cohesion Parameters, CRC Press 1983, pages 153-161.
;l 20
~.
For example, acetone, acetonitrile, propionitrile,
~' nitromethane, benzaldehyde, benzonitrile, y-butyro-
lactone, r-caprolactone, diethylsulfate, crotonaldehyde,
methyl cyanoacetate, furfural, triethyl phosphate, N, N-
Z5 d;methylformam;de, d;methyl sulfox;de, 3-methoxypropio-
,~
-~--i nitrile, N-methylpyrrol;done, nitrobenzene, nitro-
methane, n;troethane, propylene carbonate, sulfur dio-
~, xide (-10C) and sulfolane are suitable.
., .~,,~
Acetonitr;le, acrylonitr;le, benzon;trile, y-butyro-
lactone, d;ethyl sulfate, furfural, N-methylpyrrolidone,
n;tropropane, prop;on;tr;le, propylene carbonate and
triethyl phosphate are preferably used. The ~ values of
some preferred solvents are given below:
....:
~,, . ~ .
, .....
;: "
,
":
;-
. .,
, ,; ~ ,:~ - . . .
~: . - . . ~
,j i. ,
,
132~6
- 12 -
~p ~H
Furfurai 7.452.55
Propylene carbonate 9.02.05
y-butyrolactone 8.3 3.7
DiethyL sulfate 7.353.6
Triethyl phosphate 5.754.6
Acetonitrile 9.03.05
Acrylonitrile 8.7 3.4
Propionitrile 7.152.75
Nitro~ethane 9.42.55
` Nitropropane 6.052.05
N-methylpyrrolidone 6.153.6
~i.
In order to produce the coating composition according to
the invent;on, the oligomer and, if appropriate, the
polymer are dissolved or swollen together in the solvent~ -
This takes place at a temperature between the melting and
~ boiling point of the solvent or solvent mixture employed,
; preferably in the range 0C to 80C, in particular 20 to
60C, if appropriate with stirring or other mixing tech-
niques. The overall concentration of the two partners in
the solvent is 0.1 to 20, preferabLy 0.5 to 10% by weight.
~ If required, the other additives are then added.
,~ 25 ~y varying the mixing ratios of oligomer to polymer, the
~"'t properties of the coating composition such as surface
-~ resistance of the coating, specific resistance and film
formation, and the mechanical properties of the coating,
~ such as transparency, abrasion resistance and resistance
;~ 30 to organic and inorganic liquids, can be matched to the
requirements.
,.,~
The coating composition can be recovered as such from
; the solution or suspension by known methods but the
solution or suspension is preferably further used
directly.
, . .
-~ The solutions can be processed by customary methods, as
~ are employed in the coating of polymer solutions onto
,'''', . . .
.: ,,
-
~
'
- 13 - 1327416
any desired substrates, such as glass, metals, semi-
conductors and plastics; spin-coating, coating from a
flat film die, knife coating, dip coating, spray coating,
electrostatic spray coating, roll coating, printing and
similar processes. The coating thickness of the coating
is determined by the application method, the drying con-
ditions and the viscosity of the solutions, and is usually
in the range 2û nm to 1000 nm.
~,
The coating thickness of the conductive coa~ing further-
more depends substantially on the conductivity desired
and the transparency. As the coating thickness in-
creases, surface resistance becomes less and the trans-
parency ~orse. The conductive oligomers used have a
15 spec;fic resistance bet~een 10 3S/cm and 10 S/cm, so
- that a coating thickness of 100 nm produces a surface
~ resistance between 1 x 108 ohms and 1 x 104 ohms.
-~ The extinction at a coating thickness of 100 nm has a
; maximum in the visible region between 550 nm and 1000
20 nm, preferably between 60û nm and 900 nm, at an optical
density of 0.1 to 2.0, and the coatings usualLy appear
, blue in transmission. This means that the coatings ac-
~:,
cording to the invention are highly transparent in the
~ visible region and simultaneously fulfill very success-
-~ 25 fully the task of dissipating electrical charges. Ap-
-, plied coatings of this type of electroconductive oligo-
mers of plastics, such as poly(ethylene terephthalate),
polyethylene, polypropylene, poly(vinyl chloride), poly-
,'5 acrylonitrile and others are particularly suitable if
~; 30 they are, in addition, transparent in the visibLe spec-
traL region.
"
: .
Film sheets can be provided in a simple manner ~ith a
conductive coating by using the same processes and
machines as are used, for example, in the coating of
., .i
photograhic films, sheets or aluminum bases for offset
printing plates. In general, the conductive coating may
only be applied to one side of the fiLm as long as the
substrate is not excessively thick. If it shouLd be
" ,
, . .
,,, ~ ~ .
"~
:, ~ : , . ~ , ,
'. . ,, :
s,j,. ...
,~ , : . :
~ ~ - 14 - 1327~6
necessary, the other side of the film can also be pro-
vided with a conductive coating. This need not neces-
sarily be identical to the conductive coating on the
front side.
~ 5
In addition, it is possible to coat materials having
large internal surface areas, such as t~xtiles, fabric
webs, fibres, sponges, foamed plastic, etc. by dipping.
By applying thin coats of the coating composition accord-
`~ ing to the invention having coating thicknesses less than
m, catalysts, electroconductive wires, sensors, semi-
conductor components, solar cells, protective coatings
for solar cells, screening materials, camouflage pa;nts
in the infra-red and microwave region, heating conductors
for panel heating, special-purpose electrodes, electro- -
conductive films and fibres, films and fibres with an
;l antistatic finish, foams with an antistatic finish, films
, for audio record sleeves, conductive backing films for
-~ 20 f;lm materials, in particular for photogr~phic films and
.j .~
for X-ray films, scale covers for measuring equipment,
contrast increase for TV screens combined with preven-
~ tion of electrostatic charge either by direct coating of
`~ the front of the screen or by placing a coated glass or
- 25 plastic sheet in front of the screen, or by applying a
coated film, and touch panel arrangements for display
screens can be produced and achieved in a simple manner.
., . 1, .
:,...
The combination of the particular properties of the
~ 30 soluble, electroconductive oligomers with non-conductive
`~ polymers makes possible their use ;n applications which
were hitherto not possible since the customary conduct-
ive polymers were not soluble in the doped state. Thus,
processes which are employed in the production of micro-
~.j
electronic components can be used in an analogous man-
I ner: spin-coating and structuring using known processes
-~ of thin-film technology, for example using photo-
sensitive coatings or resists.
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The examples belo~ are intended to further ;llustrate the
;nvent;on. The amounts specified relate to the weight.
Example 1
S
6.59 parts of tetraethylammonium tetrafluoroborate, 4.56
parts of 3-methoxythiophene and 300 parts of acetonitrile
~ere introduced into an undivided electrolysis celL
equipped with cooling jacket. The cathode comprised
the V2A steel sheeting of leng~h 80 mm and ~id~h 55 mm.
The anode employed was a carbon felt (~eight per unit
area about 0.3 kg/m2, specific ~ET surface area about
1.5 m2/g) of length 80 mm, ~idth 55 mm and thickness
3 mm (geometrica~ surface area on both sides about 90
cm2). The anode was clamped at a distance of 2 cm
paralLeL to the cathode separated by a polypropylene -
net spacer. In add;tion, an Ag/AgCl reference electrode
(anode potent;al against Ag/AgCl 1.48 V) was used. At
an electrolys;s temperature of 20C and an anode cur-
rent of 400 mA, a cell voltage of S to 11 volts was
obtained. After half the amount of current theoretically
~ 3
required, the anode, charged with the oligomers, was
replaced by a new one and the electrolysis was termin-
ated after consumpt;on of the theoretical amount of
current. Each of the anodes charged with the crude
product ~ere dried immediately after replacement and
placed in a bath containing methylene chloride and
; repeatedly digested therein for a relatively long
period. After re-drying, the oligomer-charged carbon
;~i 30 felts were digested in a bath containing ace~onitrile
-` until the oligomers had dissoLved virtuaLly compLeteLy.
-i~ The intense dark-blue solution was evaporated to dryness
~,r, on a rotary evaporatsr. The crude product was commi-
;- nuted mechanically, washed with water, dried, digested
for tweLve hours using methylene chLoride, subse~uently
fiLtered off and dried. For further purification, the
material obtained was re-dissolved in acetonitrile and
centrifuged for 0.5 hours at 10,000 rpm, and the centri-
-:
fugate was 0vaporated to dryness on a rotary evaporator.
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2.2 parts of a solid with a bronze metallic luster were
obta;ned. The elemental analysis gave the following
values :
45.1X of C, 3.2X of H, 23.1% of S and 9.6% of F. A
compressed powder disk of the ground product had a spe-
cific conductivity of 7.1 x 1û 3 S/cm. In DTG, a
weight loss of less than 10% was observed up to 260C.
The DSC exhibited a maximum at 305C. In the mass
:.
spectrum of the undoped form, the molecular ions of the
10 pentamer (mte = 562) and the hexamer (m/e = 674) were
detected. The GPC of the undoped form showed that more
than 80Z of the product comprised pentamers and hexamers.
In the UV/VIS/NIR spectrum in tetrahydrofuran, the un-
doped pentamer exhibited a maximum at A = 460 nm and the
undoped hexamer a maximum at ~ 486 nm.
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The following components were dissolved by stirring in
100 ml of acetonitrile. 0.8 9 of the above-described
oligomer and 0.2 9 of polymethyl methacrylate, having a
melt flow index MFI (230/ 3,8) = 11.0 9/10 min, determined
in accordance with DIN 53735, and a molecular weight of
1.2 x 10 5 g/mol. The solution was coated onto a 50 mm x
50 mm glass substrate vith the aid of a spin coater at a
speed of about 1000 rpm. The thickness of the film was
measured using a profilometer and was 53.6 nm. The coating
was provided at 2 opposite edges with conduct;ve silver
and contacted on each side with two copper wires of dia-
meter 50 ~m. The specific resistance was measured at vol-
tages bet~een -10 V and 100 V in 10 V steps using an
electroneter in V/I mode. The value determined for the
~ specific resistance was 2 x 103 ohm. cm. For the same
;- coating a transmission spectrum ~as recorded vhich had a
maximum at ~60 n~ and an optical density of 0.37.
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~-- 35 The same coating solution was spun, under the same con-
ditions onto a larger glass plate measuring 20 cm x 20 cm.
' Extremely homogeneous films of uniform coating thickness
- were obtained on the glass. These coated glass plates are
~ highly suitable for increasing the contrast of video
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1327~16
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screens if they are mounted in front of the screen. In
addition, it was possible to use, due to their conduc-
tivity, for dissipating electrostatic charges induced
by the screen. For this purpose, the conductive coating
was contacted at the edge with a thin copper wire, as
described above and the latter was connected to the
protective ground of the instrument. Soil;ng of the
; screen was thereby prevented and at the same t;me the
contrast was ;ncreased.
Example 2
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` Using the same materials as in Example 1, the following
`~ solution was prepared:
0.5 9 of conductive oligomer and 0.5 9 of poly(methyl
` methacrylate) in 100 ml-of acetonitrile. After spin- ~
~- coating and measurement as described in Example 1, the
following measured values were obtained: coating thick-
ness 49.7 nm, specif;c res;stance 8 x 103 ohm.cm,
0ax;mum ext;nction at 660 nm, and optical density of
~l 0.27. This solution was likewise spun onto relatively
,r~i large glass plates and mounted in front of a display
monitor. Here too, an improvement ;n contrast and a
good ant;stat;c act;on were obta;ned.
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Exa~ple 3
~' Us;ng the same mater;als as ;n Example 1, the following
solution was prepared in 100 ml of acetonitrile and sp;n-
i 30 coated onto glass plates: 0.2 9 of conductive oligomer and 0.8 9 of poly(methyl methacrylate). Measurement in
the manner descr;bed above gave the following data:
, Coating thickness 50.5 nm, specific resistance 4 x 106
-~ ohm.cm, maximum extinction at 650 nm and optical dens;ty
- 35 of 0.1. Mounted in front of a video screen, an anti-
static action ~as obtained, but ~ith virtually no ;mprove-
ment in contrast.
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Exa~ple 4
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The fo~owing components were dissolved by stirring in
28 ml of acetonitrile, 60 ml of 3 methoxypropionitrile and
10 ml of y-butyrolactone: 1.0 9 of conductive ol;gomer
from Example 1 and 1.0 9 of poly(methyl methacrylate) of
the same type as in Example 1. A deep blue solut;on was
obtained and was used in a kiss-coat apparatus to coat
~` a polyester film of length 1.5 m and width 0.2 m. The
thickness of the film was 125 ~m. In the apparatusO the
~ film was stuck together to form a continuous loop and
! passed over two rolls arranged vertically. One of the
;~ rolls could be driven by a motor. At the lower roll, of
, diameter 200 mm, the film rested on the liquid surface
of the coating solution, the solution wetting the film
and forming a meniscus. With the aid of the driven rolls, -
the film was coated on the surface. A drying device ~as
located on the machine so the fiLm could be dried at the
same time. At a band speed of 3.0 m/min, a highly adherent
~-~ 20 film which had a surface resistance of 2.1 x 108 ohm
and an optical density of 0.32 at a wavelength of 670 nm
was thus obtained on the film. The uniformity of the
film was excellent and the adhesion of the film thus
j.l,
coated exhib;ted no defects, even after draw;ng sver a
sharp edge.
Exa-ple 5
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4.33 parts of 3-methoxythiophene, 0.26 parts of 3-
~ 30 ethoxythiophene, 4.34 parts of tetraethylammonium tetra-
-` fluoroborate and 250 parts of acetonitrile were eLectro-
; lyzed in an electrolysis cell of the type in ExampLe 1
but w;thout reference electrode, and the product was
^ worked up. 1.2 parts of a solid with a bronze metallic
~ 35 luster were obtained. The elemental anaLysis gave the
`i following values. 42.5% of C, 2.9X of H, 22.9X of S and
9.0X of F. A compressed powder disk of the ground pro-
duct had a specific conductivity of 2.0 x 10 3 S/cm.
-s In the DTG, a we;ght loss of less than 10% was observed
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up to 210C. The DSC exhibited a maximum at 320C.
In the mass spectrum of the undoped form, the molecu~ar
ion of the pentamer (m/e = 576) comprising four methoxy-
thiophene units and one ethoxythiophene unit was
S detected.
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1 9 of this oligomer was dissolved in 100 ml of a sol-
vent mixture having the following composition: 2 parts
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of acetonitr;le, 4 parts of propionitrile, 2 parts of
3-methoxypropionitrile and 2 parts of nitromethane.
;~` 0.8 9 of poly(vinyl acetate) (molecular weight about
` 35,000, softening point 80 to 100C) was added to this
solution and dissolved by stirring and the mixture was
~, used for coating in the same apparatus as described in
Example 4, the band speed being 2.5 m/min. The film used
` was a 100 ~m thick polyester film. A coating which adher~d-
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very well to the film and had a surface resistance of
, 2 x 107 ohm was obtained.
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Exa-ple 6
The following solution was prepared: 1 9 of a conductive
~i oligomer, whose preparat;on is described in Example 1,
was dissolved by stirring at room temperature in 40 ml
j~,
of y-butyrolactone, 20 ml of acetonitrile, 20 ml of
~;!,',',., acetone and 10 ml of propionitrile. This solution was
,.,'~`! used to coat a PVC film of thickness 200 ~m using a
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, commercially available spray-coating apparatus. The
thickness of the sprayed-on conductive coating depended
~`~ 30 on the duration of exposure. The surface resistance of
s~ the coated film was measured in accordance with DIN
53482 using a protective ring electrode and was 4 x 106
ohm, and the optical density was 0.8 at 690 nm.
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Exa-ple 7
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5.13 parts of 3-ethoxythiophene, 4.34 parts of tetra-
- ethylammonium tetrafluoroborate and 250 parts of aceto-
nitrile were electrolyzed as in Example 1, and the
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product was ~orked up. 1,2 parts of a solid having a
bronze metallic luster were obtained. The elemental
; analysis gave the following values: 48.1% of c, 4.2% of
H, 19.9~ of S and 8.5% of F. A compressed po~der disk of
` 5 the ground product had a specific conductivity of 1.0 x
10 2 S/cm. In the DTG, a weight loss of less than 10% was
observed at 205C. The DSC exhibited a maximum at 305C.
In the mass spectrum of the undoped form, the molecular
ion of the pentamer tm/e = 632) was detected.
1 9 of the abovementioned oligomer and 105 9 of a
styrene acrylonitrile copolymer were added to a solvent
mixture compr;s;ng 30 ml of y-butyrolactone, 10 ml of
nitromethane, 10 ml of N-methylpyrrolidone and 10 ml of
butyronitrile and d;ssolved by stirring at 50C. Th;s
solut;on was transferred ;nto a screen-pr;nting appara-
tus and used to print a PVC film. The printed pattern
comprised mutually perpendicular l;nes of w;dth 1 mm at
a spac;ng of 1 mm. The surface res;stance, measured
Z0 using a protective-ring electrode in accordance w;th DIN
53482, was 3 x 107 ohm.
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Exaople 8
The same solution as ;n Example 7 was used to coat poly-
acrylonitrile fibres of th;ckness 100 ~m by dipping into
the solut;on. At an exposure time of 1 m;nute, a coat;ng
which adhered very well to the fiber surface ~as ob-
tained. The resistance of the fibers thus coated was
i30 measured by contact;ng w;th conduct;ve silver at a
-spacing of 10 mm and was 1 x 108 ohm.
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