Compositions – Electrically conductive or emissive compositions
Patent
1997-03-03
1999-02-16
Kopec, Mark
Compositions
Electrically conductive or emissive compositions
524 81, 524910, 524911, H01B 120, C08K 500
Patent
active
058716700
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to an electroconductive composition comprising a polymer matrix and an electroconductive network, formed in the matrix, of charge transfer (CT) complex from an electron donor and an electron acceptor, a method of producing said composition and the use thereof.
EP-A-0 285 564 describes substrates with electroconductive polymer layers, which layers contain in the polymer matrix a network of radical cation salts from tetrathio-, tetraseleno- or tetratellurotetracene and metal salts or halogens. EP-A-0 362 141 discloses substrates which are directly coated with networks of such radical cation salts. EP-A-0 362 142 describes substrates in which these networks are embedded in halogen containing polymers. EP-A-0 362 143 describes substrates in which these networks are embedded in halogen containing and photosensitive polymers. One disadvantage of these polymer layers is, that organic solutions must be used for their preparation. Another disadvantage of these layers is that the electroconducting network is formed from CT complexes having needle-like crystals, which are relatively long and big, so that the amount of CT complexes can not be lowered too much without losing electroconductivity.
It has now been found, surprisingly, that an electroconductive percolated network system of a CT complex is formed in a polymer matrix by a solvent-free in situ process using an electron donor and an electron acceptor, either the electron donor or the electron acceptor particles being weakly soluble in the polymer matrix. Surprisingly the weakly polymer-soluble particles act as nucleating agents and a microcrystalline polymer-penetrating network is formed. The polymer compositions show antistatic properties or electroconductivity. It was further found that the size of the crystal-needles and thus the electroconductivity or antistatic properties can be influenced by the size of the weakly-polymer-soluble electron donor or acceptor.
One object of the instant invention is a composition comprising a matrix of a thermoplastic, thermosetting or a structurally crosslinked polymer, in which is incorporated an electroconductive network of crystal needles of a charge transfer complex (abbreviated CT complex) of an electron donor and an electron acceptor, characterized in that the CT complex formation, either of at least one electron donor or at least one electron acceptor as weakly polymer-soluble finely devided particles, electron donor and at least one polymer-soluble electron acceptor or by at least one weakly polymer-soluble electron acceptor and at least one polymer-soluble electron donor, and are formed in the polymer mass as microcrystalline needles, which are in contact and connect the weakly polymer-soluble particles, thus forming a network which penetrates the polymer mass.
Within the scope of the present invention the term "weakly polymer-soluble" means that seed particles are being dissolved slowly so that crystal growth is maintained only at the seed surface.
Preferably, the diameter of these particles is from 10 nm to 20 .mu.m, more preferably 20 nm to 20 .mu.m, and most preferably 50 nm to 5 .mu.m.
The crystals of CT complex are contained in the polymer matrix in an amount of preferably 10.sup.-3 to 2% by weight, more preferably 10.sup.-2 to 1% by weight based on the polymer.
If S.sub.CT denotes the solubility of the CT complex in the polymer (in Mol/Kg) and if it is assumed that the molecular weight of the weakly polymer-soluble donor or acceptor is about one half of the molecular weight of the corresponding CT complex, the loading of the polymer with the weakly polymer-soluble donor or acceptor, X.sup.P.sub.D or X.sup.P.sub.A (in Mol/Kg), should be: .
The factor of 100 ensures complete crystallization of the CT complex.
The above crystals have a length of preferably 0.1 .mu.m to 1000 .mu.m, more preferably 1 .mu.m to 500 .mu.m, and most preferably 10 .mu.m to 400 .mu.m, and an aspect ratio (length:width ratio) of preferably 1 to 10000, more preferably 10 to 5000 and most preferably 10 to 100
REFERENCES:
patent: 4769177 (1988-09-01), Hocker et al.
patent: 5492652 (1996-02-01), Chetcuti
patent: 5545703 (1996-08-01), Castellucci
Jeszka et al "A New Method of Growing Crystalline Networks . . . ", Polymers for Advanced Technologies, vol. 3, pp. 139-142, 1992 (no month).
Hilti Bruno
Minder Ernst
Pfeiffer Jurgen
Ciba Specialty Chemicals Corporation
Hall Luther A. R.
Kopec Mark
Levine Jacob M.
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