Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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FILE, Wi~-tN THIS Ai~~a
- 1 - ~tfi~TRANSLATION
Conducting oceanic-inorganic hybrid materials
The present invention relates to mixtures of conducting organic polymers and
reaction products of polyfunctional organosilanes, conducting organic-
inorganic
S hybrid materials obtained therefrom, and their use for coating surfaces.
Glass moulded parts and plastics moulded parts become electrostatically
charged by
friction or application of charges, for example electron beams in TV picture
tubes.
As a result of these charges the moulded parts rapidly become covered with
dust due
to attraction of dust, which is undesirable in practice. There is therefore
the need to
protect these moulded parts against electrostatic charging. This protection
can be
achieved for example by coating the moulded parts with an antistatic coating.
Following the definition given in ISO 2878, antistatic materials are
understood to be
those having surface resistances of between SO kS2/0 and 100 MS2/C. Conducting
1 S materials are defined as those having surface resistances of < SO kS2/~.
With sufficiently conducting materials, in addition to the antistatic effect a
screening
effect against electromagnetic radiation, as is emitted for example from
cathode ray
tubes, is also achieved. For an effective radiation screening the surface
resistance
must be less than 3 kS2/~.
For practical use these coatings must also have a sufficient mechanical
strength and
adhesion. Especially in the case of glass as Garner, the layers must be
sufficiently
scratch-resistant in order to avoid damage to the coating when cleaning the
coated
2S surfaces and thus loss of the antistatic and/or conducting effect.
Electrically conducting polymers, for example polythiopenes, for producing
antistatic and/or conducting coatings are known from the literature Examples
thereof may be found in EP-A 440 9S7 and DE-OS 42 11 459.
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The use of these polythiophene salts for giving glass an antistatic finish is
described
in DE-OS 42 29 192. It has been found however that these coatings are not
sufficiently scratch-resistant in practice for some applications.
Scratch-resistant coatings based on hydrolysed siloxanes are known from EP-A
17
187. These however are not compatible with preparations of polythiophene
salts.
Poly-3,4-ethylenedioxythiophene-containing coatings on image screens are
described in WO 96/05606. In order to improve the scratch resistance of the
coatings and obtain anti-reflecting properties, layers of SiOz and/or TiOZ
obtained
for example from metal alkoxides are applied thereto via the sol-gel process.
A disadvantage is that already with layer thicknesses that are only slightly
more
than 100 nm, the transmission falls below 60%. The layer must therefore have
exactly the same thickness over the whole surface. The reproducible
application of
such thin coatings is however technically difficult..
A further disadvantage of this process is that conducting coatings having the
required scratch resistance can only be obtained if the conducting layer is
provided
with at least one scratch-resistant covering layer. To obtain suitable
coatings having
anti-reflecting properties it is necessary to apply up to four different
layers in
succession. This is technically extremely complicated. Also, with each
additional
layer there is an increasing danger that the overall laminar composite will
exhibit a
defect.
The present invention provides mixtures which, when applied to suitable
substrates,
produce after removal of the solvents firmly adhering, conducting coatings
having
improved scratch resistance and transmission of visible light.
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It has now been found that the aforementioned requirements can be fulfilled if
mixtures of conducting organic polymers with reaction products of
polyfunctional
organosilanes and optionally further components such as metal alkoxides, metal
oxides or metal oxide-hydroxides are used.
The present invention accordingly provides mixture containing:
A) preparations of polythiophenes,
B) reaction products of polyfunctional organosilanes,
C) optionally reaction products of alkoxides of the elements B, Al, Si, Sn,
Ti,
Zr,
D) optionally metal oxides or metal oxide-hydroxides of the elements B, Al,
In,
Si, Sn, Ti, Zr,
E) Solvents
i
O O -
O
L ~S
As component A), there are preferably used preparations of polythiophenes such
as
are described in DE-OS 42 11 459, EP-A 339 340 and EP-A 440 957. The
preparations contain polythiophene salts of the type polythiophene"'+, Anm~,
wherein
the polythiophene cation polythiophene'T'+ contains positively charged or
uncharged
units of the formula (I),
wherein
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A denotes a C 1-C4-alkylene radical optionally substituted with C ~ _CZO alkyl-
,
-CHZOH or C6_C~4-aryl groups. The number of units in the polythiophene
cation may be between 5 and 100.
Anm- denotes a polyanion.
Examples of polyanions that may be used according to the invention are the
anions
of polymeric carboxylic acids such as polyacrylic acids, polymethacrylic
acids,
polymaleic acids, as well as anions of polymeric sulfonic acids such as
polystyrenesulfonic acids and polyvinylsulfonic acids. These polycarboxylic
acids
and polysulfonic acids may also be copolymers of vinylcarboxylic acids and
vinylsulfonic acids with other polymerisable monomers such as acrylic acid
esters
and styrene.
The mean molecular weight M of the polymeric acids from which are derived the
polyanions that may be used according to the invention is 1000 to 2,000,000,
preferably 2000 to 500,000. The polymeric acids or their alkali salts are
commercially available or can be prepared by methods known per se, such as
those
described for example in Houben-Weyl: "Methoden der organischen Chemie", Vol.
E20, "Makromolekulare Stoffe", Part 2, p.1141 ff.
The mixtures according to the invention contain as component B) reaction
products
of polyfunctional organosilanes. Polyfunctional organosilanes within the
context of
the invention are those that contain at least 2, preferably at least 3 silicon
atoms per
molecule, that in each case contain 1 to 3 alkoxy or hydroxyl groups, and that
are
coupled via at least one Si-C bond to a structural unit joining two silicon
atoms.
Bonding structural units within the context of the invention may in the
simplest case
be linear or branched C1 to C~o- alkylene chains, CS to Coo-cycloalkylene
radicals,
aromatic radicals such as phenyl, naphthyl or biphenyl, or also combinations
of
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aromatic and aliphatic radicals. The aliphatic and aromatic radicals may also
contain
hetero atoms such as Si, N, O, S or F. Furthermore, chain, ring or cage
siloxanes,
for example sils~squioxanes, may be mentioned as coupling structural units.
Examples of coupling structural units are given hereinafter, wherein X denotes
Si
atoms that contain 1 to 3 hydrolysable and: or condensation-crosslinking
groups, and
Y denotes corresponding Si atoms that are bound via an alkylene chain to the
coupling structural unit; n denotes a number from 1 to 10, and m denotes a
number
from 1 to 6:
\ X X
X-(CH2)~ X . X ~ X . 'i~~~
' ~ m '
X X X
1~ X \
. Y ( Y
X m '
X
Y ~ Y Y
Y
~~~~ Y
Y ; . Y m
,0 Y
m
X ' ~ ~~' ~/ ,
i CH3 CHI
Y ~ ~ O ~ ~ Y X ~ ~ C ~ ~ >( ; Y / \~ C ~ ~ Y
CH3 CH~
Y ~ Y
i I I
Y Si Y ' Y-Si-Y ; Y-Sn-Y ; Y- i n-Y
I
Y R Y R
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wherein R is an organic radical, for example alkyl, cycloalkyl, aryl or
alkenyl.
Examples of polyfunctional organosilanes are compounds of the general formula
(II)
S R34-isl~(CH2)nsl(OR4)aR53-a~i (II)
where
i = 2 to 4, preferably i = 4,
n = 1 to 10, preferably n = 2 to 4, particularly n = 2, and
R3 = alkyl or aryl,
R5 = alkyl or aryl, preferably RS = methyl,
a=lto3,
wherein
R4 = alkyl, aryl, preferably R4 = methyl, ethyl, isopropyl;
in the case where a = 1, R~ may also be hydrogen.
Further examples are cyclic compounds of the general formula (III)
i(OR')~Rg3-
( ~ H2)n
SI O
~ s (
m
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where
m = 3 to 6, preferably m = 3 or 4,
n = 2 to 10, preferably n = 2,
R6 = C1-C6 alkyl or C6-C,4 aryl, preferably R6 = methyl, ethyl, particularly
preferably R6 = methyl,
R8 = alkyl, aryl, preferably R8 = methyl,
c = up to 3, wherein
R' = alkyl, aryl, preferably R' = methyl, ethyl, isopropyl;
in the case where c = l, R' may also be hydrogen.
Further examples of polyfunctional organosilanes are compounds of the general
formula (IV)
S1[OS1R'~z(CHz)pSl(OR9)dR'°3-a~4 - (IV)
where p = 1 to 10, preferably p = 2 to 4, particularly preferably p = 2,
R" - alkyl, aryl, preferably R~ I = methyl,
R'° - alkyl, aryl,.preferably Rl° = methyl,
d = 1 to 3, wherein
R9 = alkyl, aryl, preferably R9 = methyl, ethyl, isopropyl;
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_g_
in the case where d = l, R9 may also be hydrogen.
Examples of polyfunctional organosilanes according to the invention are also
silanols such as Si[CH~)zSi(OH)(CH3)2]4 and cyclo-[OSiMe((CH2)2Si(OH)Mez)]a,
S or alkoxides such as cyclo-[OSiMe((CHZ)ZSi(OEt)ZMe)]4 and cyclo-
[OSiMe((CHZ)ZSi(OMe)Mez)]a.
The mixtures according to the invention may contain as component C) reaction
products of alkoxides of the elements B, Al, Si, Sn, Ti, Zr.
The alkoxides that may be used in the preparation of the mixtures according to
the
invention preferably correspond to the general formula M(OR)y, where y has the
value 3 if M denotes boron or aluminium, and y has the value 4 if M denotes
silicon,
tin, titanium or zirconium. Examples of alkoxides that may be added in the
preparation of the mixtures according to the invention in order to improve the
scratch resistance of coatings produced therefrom are Si(OEt)4, Al(O'Pr)3 or
1 S Zr(O'Pr)4, preferably Si(OEt)4. By adding titanium alkoxides, for example
Ti(O'Pr)4
or Ti(O"Bu)4, the refraction index of the conducting, organic-inorganic hybrid
material produced from the mixtures according to the invention can be
increased.
During the production process of the mixtures according to the invention,
solvolysis
products and condensation products are formed from the alkoxides, for example
by
reaction with the solvent, polyfunctional organosilanes, polythiophene
preparations,
catalysts or by self condensation. In order to reduce the reactivity of
readily
hydrolysable and condensable metal alkoxides and to avoid the formation of
deposits, these metal alkoxides may first of all already be reacted with water
before
they react with the polyfunctional organosilanes. These solvolysis products
and
condensation products form the component C) of the mixtures according to the
invention.
Details of the hydrolysis and condensation of polyfunctional organosilanes and
their
mixtures with metal oxides may be found for example in DE-OS 196 03 242,
German Patent Application 196 03 241.5 and WO 94/06807.
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The polyfunctional organosilanes are reacted with water in the presence of a
catalyst,
preferably in a solvent, for example an alcohol, and optionally in the
presence of
metal alkoxides. Inorganic or organic acids, for example formic acid, are used
as
catalysts. The solvolysis and condensation products of the polyfunctional
organosilanes form the component B) of the mixtures according to the
invention.
The mixtures according to the invention may contain as component D) metal
oxides
or metal oxide-hydroxides of the elements B, Al, In, Si, Sn, Ti or Zr. Mixed
metal
oxides, for example indium-tin oxides (ITO) may also be used. In order to
obtain
transparent coatings, particles with primary particle sizes in the range from
1 to 50
nm are preferably used. Their incorporation in the mixtures according to the
invention is best achieved by adding the particles as a dispersion in a
solvent, for
example water or alcohols. A dispersion of SiO, (primary particle size ca. 9
nm) in
isopropanol may be mentioned by way of example.
By adding fillers such as glass powder, calcium carbonate, calcium sulfate,
barium
sulfate or layer-type silicates (talcum, kaolin, mica), the conductivity of
the
amorphous organic-inorganic hybrid materials obtainable from the mixtures
according to the invention may be improved still further.
The mixtures according to the invention are prepared from the reactive
solutions
obtained by reacting polyfunctional organosilanes or their mixtures with
alkoxides,
metal oxides or metal oxide-hydroxides, by adding preparations of
polythiophenes
while stirring. In order to obtain homogeneous mixtures the components are
preferably diluted with solvents that are at least partially water-miscible,
since the
polythiophene preparation can in general only be prepared as a dilute aqueous
solution and with the latter homogeneous mixtures can as a rule only be
obtained in
a narrow range in the reactive solution.
It is moreover also possible to add the corresponding monomers, for example
3,4-
ethylenedioxythiophene to the reaction solution and to polymerise it, for
example in
the presence of iron sulfonate.
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As solvents with which the reaction solutions may be diluted before adding the
polythiophene preparations, there may be mentioned by way of example alcohols
such as methanol, ethanol, isopropanol, n-butanol, sec.-butanol, ethylene
glycol or
glycerol, ketones such as acetone or methyl ethyl ketone, and amides such as
N,N-
dimethylformamide or N-methylpyrrolidone. Mixtures of two or more solvents may
also be used.
Preferably the amount of polythiophene salts in the mixtures according to the
invention is 0.1 to 20 wt.%, preferably 1 to 10 wt.%, referred to the sum of
the
components A), B) and C).
The mixtures according to the invention contain solvents as component E).
These
solvents serve to produce a homogeneous mixture of the individual components.
The mixtures according to the invention may contain as solvents water,
inorganic
acids such as hydrochloric acid, or organic solvents. Organic solvents may for
example include alcohols such as methanol, ethanol, isopropanol, n-butanol,
sec.-
butanol, ethylene glycol or glycerol, ketones such as acetone or methyl ethyl
ketone,
amides such as N,N-dimethylformamide or N-methylpyrrolidone, or organic acids
such as formic acid. Generally the mixtures according to the invention contain
a
mixture of solvents, since the components necessary for preparing the mixtures
according to the invention are mostly used in dissolved form.
In a particular embodiment an organosilane of the formula
Si[(CH,)2Si(OH)(CH3)2]a
is first of all reacted in the presence of tetraethyl orthosilicate (1
mole:4moles) in
ethanol with water and formic acid to prepare the mixtures according to the
invention; after one hour's reaction time the reaction mixture is diluted with
n-
butanol and ethylene glycol and an aqueous solution is added to a preparation
of
poly-3,4-ethylenedioxythiophene / polystyrenesulfonic acid.
Inorganic-organic hybrid materials are obtained by removing the solvent from
the
mixtures according to the invention. These hybrid materials can be used for
example as an antistatic and/or conducting surface coating.
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For this purpose the mixtures according to the invention are applied to
surfaces; after
the evaporation of the solvents and the hardening of the formed organic-
inorganic
hybrid material, conducting, scratch-resistant coatings are obtained.
The coating of surfaces with the mixtures according to the invention may be
effected
by conventional techniques, for example spraying, application with a doctor
blade,
dipping, flow coating or spin coating.
The applied- layer of inorganic-organic hybrid material will preferably have a
thickness of 20 nm to 100 p.m, particularly preferably a thickness of 100 nm
to 10
pm. The conductivity of the layers is preferably 0.2 to 1O8S2/I7, particularly
preferably 100 to 1O8S2/C.
The coatings are hardened at temperatures of 15°C to 250°C,
preferably SO°C to
200°C, particularly preferably 100°C to 200°C.
Surfaces of moulded parts and films of inorganic or organic materials such as
plastics may for example be coated with the mixtures according to the
invention.
Examples of suitable plastics are those based on polyethylene, polypropylene,
polyesters such as polyethylene terephthalate and polyethylene naphthalate,
polystyrene, polycarbonate, ABS, polyacrylate, polyacrylonitrile, cellulose
derivatives such as cellulose acetate, polyamides, polyvinyl chloride,
optionally
glass fibre-reinforced epoxy resins, -as well as copolymers or blends of the
aforementioned polymers.
The mixtures according to the invention are particularly suitable for coating
inorganic moulded parts of materials such as glass or ceramics, for example
materials containing aluminium oxide, silicon carbide or silicon nitride.
The mixtures according to the invention are preferably used for the antistatic
andlor
conducting coating of glass cathode ray tubes.
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Examples
A ca. 1.3% poly-3,4-ethylenedioxythiophene/polystyrene sulfonate solution
(PEDT/PSS) in water is used as conducting organic polymer.
The polyfunctional organosilanes that are used, for example
Si[(CH2)ZSi(OH)(CH3)z]a or cyclo-[OSiMe((CH2)2Si(OEt)zMe)]4, were prepared by
hydrosilylation of tetravinyl silane or cyclo-[OSiMe(CzH3)]4 with HSiCIMe2 or
HSiCI2Me, followed by hydrolysis and alcoholysis. Further details may be found
in
DE-OS 196 03 242 and German Patent Application 196 03 241 5.
The surface resistance was measured according to the details given in DIN IEC
93.
For this purpose two 5 mm wide and 5 cm long conducting silver strips were
applied
at a distance of S cm apart to the sample surface. The conducting silver
strips were
hardened, unless otherwise stated, by heating for 15 minutes at 160°C.
The pencil hardness was measured according to the instructions given in ASTM D
3363.
Example 1
(a) 20 g Of Sl[(CH2)2S1(OH)(CH3)2]4, SO ml of ethanol, 40 ml of tetraethyl
orthosilicate (TEOS), 10 ml of water and 6 ml of formic acid were combined
in this order while stirring and then stirred for a further 90 minutes.
(b) 40 ml of ethylene glycol, 40 ml of n-butanol and 40 ml of the PEDT/PSS
solution were added while stirring to 40 ml of the solution from (a). Three
glass plates were spray coated with this homogeneous mixture, using
nitrogen as carrier gas. The coatings were then immediately dried for 15
minutes at 160°C; after drying, the surface resistance was measured.
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Sample Surface resistanceLayer thickness
[S2/~]
1 15000 < 0.5 ~m
2 12000 1.4 pm
3 _ 12000 not measured
All films were transparent.
(c) - The mixture prepared according to (b) was stored for 2 days in a
refrigerator
(ca. 4°C), following which no change was observed. The homogeneous
mixture was then applied by means of a doctor blade (wet film thickness
120 Vim) to a glass plate and the surface resistance was measured.
Sample Surface resistanceSurface thickness
[S2/I7]
4 2200 4.8 ~.m
The coating was crack-free, transparent and homogeneous.
Example 2
(a) 10 g of Si[(CHZ)2Si(OH)(CH3)z]4, 25 ml of ethanol, 20 ml of TEOS
(tetraethyl orthosilicate), 5 ml of water and 3 ml of formic acid were
combined in this order while stirnng. After ca. 10 minutes the reaction
mixture was filtered through normal filter paper and stirred for a further 80
minutes.
(b) 40 ml of ethylene glycol, 40 ml of n-butanol and 60 ml of the aqueous
PEDT/PSS solution (previously filtered through cotton wool) were added
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while stirring vigorously to 40 ml of the lacquer solution from (a) and the
whole was stirred for 10 minutes. The homogeneous mixture thus obtained
was sprayed on glass plates using nitrogen as Garner gas, and the coating was
hardened for 15 minutes at 160°C.
Sample Surface resistanceLayer thicknessTransmissionPencil hardness
[~] (400-700
nm)
1 4200 1.7 ~m >83% > 7H
2 5500 1.1 pm >90% > 7H
Both films were transparent.
Example 3
(a) 25 g of a 36.x% solution of cyclo-[OSiMe((CHZ)2Si(OH)Me,)]4, 12.5 ml of
TEOS, 3.2 ml of water and 2 ml of formic acid were combined in this order
while stirring, and the mixture was then stirred for a fizrther 75 minutes. A
clear, colourless solution was obtained.
(b) The lacquer solution obtained according to (a) was diluted according to
the
Table by stirring with solvents, and finally mixed with the aqueous
PEDT/PSS solution. Films of the homogeneous mixtures thus obtained were
applied with a doctor knife in a wet film thickness of 120 pm to glass plates;
these were dried for 10 minutes at room temperature and then for 1 S minutes
at 160°C.
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Sample - 1 2 3 4
Laquer solution of 1 1 1 1
(a) [ml]
Ethylene glycol [ml] 0.5 0.5 - 1
1-butanol [ml] 0.5 1 - -
NMP [ml] 0.5 - 1 -
2-butanol [ml] 0.5 - 1 -
1-propanol [ml] 0.5 - - 1
PEDT/PSS [ml] 1 0.5 1 1
Pencil hardness > 7 H > 6 H > 7H > 7H
Surface resistance 40 188 80 39
[kS2/~]
The conducting silver strips were hardened for 1 hour at 160°C. All
films were
crack-free, transparent and homogeneous.
Example 4 -
(a) 10 g of Si[(CHZ)2Si(OH)(CH3)2]a. 25 ml of ethanol, 20 ml of tetraethyl
orthosilicate (TEOS), 5 ml of water and 3 ml of formic acid were combined
in this order while stirring, and then stirred for a further 90 minutes.
(b) 40 ml of ethylene glycol, 40 ml of n-butanol and 40 ml of the PEDT/PSS
solution were added while stirring to 20 ml of the solution from (a).
(c) 60 ml of ethylene glycol, 60 ml of n-butanol and 60 ml of the PEDT/PSS
solution were added while stirring to 20 ml of the solution from (a).
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The homogeneous mixtures from (b) and (c) were stored for 17 hours in a
refrigerator. 3 glass plates were then spray coated, using nitrogen as carrier
;as, and
immediately afterwards dried for 15 minutes at 160°C. After cooling,
the surface
resistance was measured. Samples 1 to 3 were prepared using solution (b),
samples
4 to 6 using solution (c).
Sample Surface resistance Layer thickness
[S2/'~]
1 3400 0.8 p.m
2 2400 0.9 p m
3 1700 not measured
4 1500 not measured
5 2500 < 0.5 p.m
6 2500 < 0.5 ~m
All films were transparent.
Example 5
(a) 40 ml of ethylene glycol, 40 ml of 1-butanol and 80 ml of the PEDT/PSS
dispersion were added while stirring to 40 ml of the lacquer solution
prepared according to Example 1 (a).
(b) ca. 5 mg of mica (Mica W1, manufacturer Norwegian Talc) were added
while stirring to 2 ml of the mixture prepared according to (a). After 10
minutes' stirring a film (wet film thickness 120 p.m) was applied to a glass
plate using a doctor knife and hardened for 15 minutes at 160°C. The
surface resistance of the sample was 690 S2/~.
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Example 6
20 g of cyclo-[OSiMe((CH~)ZSi(OM)MeZ)]4, 40 ml of isopropanol, 25.7 g of TEOS
and 4.45 g of 0.1 N hydrochloric acid were combined while stirring and then
stirred
for a further hour. The mixture was then diluted with 60 ml of ethylene glycol
and
22 ml of NMP. 1 ml of the PEDT/PSS dispersion and a further 0.25 ml of
ethylene
glycol were then added to 1.3 ml of this solution. After applying the solution
to a
glass plate using a doctor blade (wet film thickness 120 p.m), the film was
hardened
for 1 hour at 140°C after having evaporated the volatile constituents.
After
application of the conducting silver and stoving at 160°C (15 minutes)
the surface
conductivity was measured and was found to be 225 S2/~. The pencil hardness
was 6
H. -
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