Conducting organic-inorganic hybrid materials

Details Conducting organic-inorganic hybrid materials Conducting organic-inorganic hybrid materials

1999-05-28

2001-03-13

Niland, Patrick D. (Department: 1714)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

At least one aryl ring which is part of a fused or bridged...

C524S183000, C524S266000, C524S368000, C524S394000, C524S404000, C524S413000, C524S430000, C524S437000, C524S588000, C524S609000, C525S100000, C525S101000, C525S417000

Reexamination Certificate

active

06201051

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to mixtures of conducting organic polymers and reaction products of polyfunctional organosilanes, conducting organic-inorganic hybrid materials obtained therefrom, and their use for coating surfaces.
BACKGROUND OF THE INVENTION
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 50 k&OHgr;/
and 100 M&OHgr;/
. Conducting materials are defined as those having surface resistances of <50 k&OHgr;/
.
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 k&OHgr;/
.
For practical use these coatings must also have a sufficient mechanical strength and adhesion. Especially in the case of glass as carrier, the layers must be sufficiently scratch-resistant in order to avoid damage to the coating when cleaning the coated 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 440 957 and DE-OS 42 11 459.
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 SiO
2
and/or TiO
2
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 object of the present invention was accordingly to provide 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.
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.
SUMMARY OF THE INVENTION
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
DESCRIPTION OF THE INVENTION
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
m+
, An
m−
, wherein the polythiophene cation polythiophene
m+
contains positively charged or uncharged units of the formula (I), wherein
A denotes a C
1
-C
4
-alkylene radical optionally substituted with C
1
-C
20
alkyl-, —CH
2
OH or C
6
-C
14
-aryl groups. The number of units in the polythiophene cation may be between 5 and 100.
An
m−
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 {overscore (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 C
1
to C
10
-alkylene chains, C
5
to C
10
-cycloalkylene radicals, aromatic radicals such as phenyl, naphthyl or biphenyl, or also combinations of 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 silsesquioxanes, 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:
wherein R is an organic radical, for example alkyl, cycloalkyl, aryl or alkenyl.
Examples of polyfunctional organosilanes are compounds of the general formula (II)
R
3
4−i
Si[(CH
2
)
n
Si(OR
4
)
a
R
5
3−a
]
i
  (II)
where
i=2 to 4, preferably i=4,
n=1 to 10, preferably n=2 to 4, particularly n=2, and
R
3
=alkyl or aryl,
R
5
=alkyl or aryl, preferably R
5
=methyl,
a=1 to 3,
wherein
R
4
=alkyl, aryl, preferably R
4
=methyl, ethyl, isopropyl;
in the case where a=1, R
4
may also be hydrogen.
Further examples are cyclic compounds of the general formula (III)
where
m=3 to 6, preferably m=3 or 4,
n=2 to 10, preferably n=2,
R
6
=C
1
-C
6
alkyl or C
6
-C
14
aryl, preferably R
6
=methyl, ethyl, particularly preferably R
6
=methyl,
R
8
=alkyl, aryl, preferably R
8
=methyl,
C=up to 3, wherein
R
7
=alkyl, aryl, preferably R
7
&

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