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...
Patent
1991-12-24
1993-09-21
Michl, Paul R.
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...
524590, 524717, 524785, 524871, 528 52, 528 56, 528 64, C08J 300, C08K 504, C08L 7500, C08G 1808
Patent
active
052470016
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to electrically conducting polymers and to production processes which enable such polymers to be obtained.
Plastic materials, which are essentially formed from a polymer mixed with a number of additives, are, from their origin, particularly suitable for the production of parts of complex shapes which are electrically insulating. It is now known to produce plastic materials which are also able to conduct electricity. These new materials are particularly useful in the low-power electrical field and for electromagnetic shielding. This latter application is particularly useful because of the multiplication both of disturbing electrical and electromagnetic fields and of electronic devices liable to be disturbed by these fields.
It is known to produce a polymer having a high electrical conductivity by assigning thereto conducting fillers such as metal particles, carbon black or metallized fibres. The electrical properties of such a composite polymer depend not only on the electrical properties of the materials comprising the matrix and the inclusions but also on the geometric shape of these inclusions (spherical, elongated, and the like) and the way in which the operation of mixing the inclusions into the elastomer has been conducted. In particular, the conducting fillers tend to form aggregates, which gives rise to the inclusion of a large amount of air in the mixture finally obtained. The presence of this air tends to reduce the conductivity of the whole, which leads to overloading of the material with conducting particles relative to the amount which would be necessary a priori for a composition without air. This overload modifies the mechanical properties of the composite material obtained to an extreme extent, essentially adversely.
It is also known to obtain intrinsically conducting polymers, such as polyacetylene, polyphenylene sulfide and the like. The conductivity is obtained by chemical or electronic modification, such as doping.
Although the conductivity thus obtained is sufficiently high for the desired applications, the other properties necessary for a correct use of these materials, in particular the stability to air, the thermal stability, the ease of use and the possibility of obtaining solid parts, are not achieved, at the very least not at the same time.
In order to alleviate these disadvantages, the invention proposes a process for the production of a composite conducting polymer, characterized in that a first solution formed from a mixture of polyol and iron chloride anhydride FeCl.sub.3 is first prepared and in that this solution is then mixed with pyrrole and a polyisocyanate
Other features and advantages of the invention will become more clearly apparent in the following description, which is given with reference to the appended figures, which represent:
FIG. 1: a diagram of a first process for the production of a polymer according to the invention;
FIG. 2: a diagram of a second process for the production of such a polymer; and
FIGS. 3 and 4: characteristic curves of the electrical properties of these materials.
Polyurethanes are polymers which belong to a family whose members may have very different electrical and mechanical properties. A polyurethane is a polymer which possesses the urethane chemical group, the formula of which is >N--CO--O--, repeated more or less regularly.
These polymers are obtained from two liquid compounds: a polyol and a polyisocyanate monomer which contains at least 2 NCO groups. On mixing these, a chemical reaction is caused which initiates a cross-linking of the reaction product, which results in a synthetic elastomer being obtained.
On the other hand, it is known to polymerise pyrrole, the formula of which is: C.sub.4 H.sub.5 N, by chemical, electrothermal or thermal routes, in liquid phase or in vapor phase. If an electronic modification of the polypyrrole is induced during this polymerization, by doping or by oxidation, the conductivity of the polymer obtained is modified, the polymer becoming conductive.
The base elements us
REFERENCES:
patent: 4617353 (1986-10-01), Myers
patent: 4935165 (1990-06-01), Wessling et al.
Database Chemical Abstracts, (Note: STN), vol. 108, No. 8, 1987, (Columbus, Ohio, US), Xiantong Bi et al.: "An electrically conductive composite prepared by electrochemical polymerization of pyrrole into polyurethane", voir resume No. 64505z, & Synth. Met. 22(2), 145-156.
"Thomson-CSF"
Michl Paul R.
Niland Patrick
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