Coating processes – Electrical product produced
Patent
1981-10-19
1984-05-15
Smith, John D.
Coating processes
Electrical product produced
148 63, 148 631, 148 635, 357 8, 427 86, 427 87, 427115, 427125, 4272556, 427292, 427295, 427309, H01L 2928
Patent
active
044488033
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The invention generally relates to semi-conducting N.sub.4 -chelate coatings and their manufacture on electrically conducting substrates suitable for producing industrial electrodes of different types.
BACKGROUND ART
Monomeric and polymeric phthalocyanines exhibit interesting electronic, electrocatalytic and photo-electrochemical properties.
Eley and Vartanyian found in 1948 that the conductivity of phthalocyanines increases exponentially with temperature in the form of a Boltzmann distribution, which is typical for so-called intrinsic semi-conductors.
Since then there have been various publications relating to investigations of the influence of the conditions of preparation on the conductivity of monomeric and polymeric phthalocyanines. The following publications may be cited for example: Technology, West Germany, July, 1976 083
These publications relate to formation of monomer and polymer chelates by reaction in a solution or melt. The resulting monomeric and polymeric chelates (primarily oligomers) are dissolved in concentrated sulphuric acid, diluted in water, deposited on active carbon and processed into a gas-diffusion electrode for oxygen reduction.
It has also been suggested to form polymeric phthalocyanines by a homogenous gas phase reaction of tetracyanobenzene and a volatile metal chelate, dissolution in sulphuric acid, dilution and deposition on a carbon support. This method was described for example by A. J. Appleby and M. Savy in Electrochimica Acta, Vol. 21, pages 567-574 (1976).
A. P. Berlin et al (Doklady Akademii Nauk SSR, Vol. 136, no. 5, pages 1127-1129) describe the formation of very thin films of polymeric complexes obtained from tetracyanoethylene and copper, iron or nickel. The thickness reported in the case of iron corresponded to 0.05-0.3.mu.. However, such thin films show insufficient chemical resistance in corrosive media.
Naraba et al (Japanese Journal of Applied Physics, Vol. 4 (12) 977-986, describe the preparation of a poly-tetracyanoethylene chelate film. This work relates primarily to Cu and reports a film thickness of 1 mm, with a significant Cu gradient across the film. This publication describes applying a vacuum of 10.sup.-5 mm Hg and using high frequency heating to get a clean surface; such a procedure is hardly suitable for an industrial process.
In a further publication of K. Hiratsuka et al in Chemistry Letters, pages 751-754, 1979, surface annealing under a hydrogen atmosphere is described as a prerequisite for complete removal of surface oxides prior to chelation. The temperature range of 250.degree.-350.degree. C. and an initial reactant amount related to sample area corresponding to 20-40 g/m.sup.2 are mentioned.
Polymeric phthalocyanines can exhibit high electrical conductivities which may be greater by ten orders of magnitude than the conductivities of monomeric phthalocyanines. They may have semi-conducting properties of the n or p type, depending on the conditions of preparation.
N.sub.4 -chelates and more particularly metal phthalocyanines were found to exhibit interesting catalytic properties for oxygen reduction in fuel cells where acid electrolytes are used to avoid carbonate formation.
Polymeric phthalocyanines of high molecular weight are resistant to attack by acid media and exhibit high catalytic activity for oxygen reduction.
Polymeric phthalocyanines cannot be sublimated, but it has been reported that polymeric films may be obtained after prolonged exposure of metal plates to tetracyanoethylene (TCNE) at elevated temperatures.
However, investigations have shown different methods and conditions of preparation can lead to N.sub.4 -chelates with quite different electrical and catalytic properties, as well as different molecular weights and chemical or physical stability.
It has also been found that the chemical and physical stability of oligomeric and polymeric N.sub.4 -chelates depends on the starting materials of the chelates, their purity, the conditions under which they are produced and the structure of the resulting chelate.
REFERENCES:
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Delacote et al., "Electron Injection in Thin Films of Copper Phtalocyanine", Solid State Communications, vol. 2, pp. 373-376, 1964.
Okamoto et al., "Organic Semiconductors", published by Reinhold Publishing Co., pp. 148-157, .COPYRGT.1964.
Hamann et al., "Electrical Properties of Organic/Inorganic Thin Film Sandwiches", Thin Solid Films, vol. 36, No. 1, Jul. 1976, pp. 81-84.
M. Meier et al.: Journal Physical Chemistry, 81, 712 (1977), DE OS No. 25 49 083.
D. Wohrle, in Advances in Polymer Science, vol. 10,35 (1972).
Electrochimica Acta, vol. 21, pp. 567-574 (1976), A. J. Appleby and M. Savy.
V. S. Bagotzsky et al., Journal of Power Sources 2 (1977/78), 223-240.
H. Meier et al., Berichte der Bunsengesellschaft Bd 77, nr. 10/11, 1972.
H. Ziener et al.: Project report to the Federal Ministry for Research and Technology, West Germany, Jul. 1976.
Doklady Akademii Nauk SSR, vol. 136, No. 5, pp. 1127-1129, A. P. Berlin et al.
Japanese Journal of Applied Physics, vol. 4 (12) 977-986, Naraba et al.
Chemistry Letters, pp. 751-754 (1979), K. Haratsuka et al.
Gauger Jurgen F.
Hinden Jean M.
Katz Michael
Diamond Shamrock Corporation
Harang Bruce E.
Hazzard John P.
Smith John D.
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