Process for the production of a cation exchange diaphragm and the diaphragm obtained by this process
AssigneeCommissariat a l'Energie Atomique
InventorsGilbert Gaussens, Francis Lemaire
Life of this patent
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Abstract
Cation exchanger diaphragm which can in particular be used as a solid electrolyte. This diaphragm comprises a grafted copolymer film, particularly polyethylene grafted by styrene and has an exchange capacity exceeding 0.5 meq/g, a resistivity below 100.OMEGA..cm, a swelling in water exceeding 30% compared with the dry mass and a permeability relative to oxygen and hydrogen such that in the electrolysis of water these two gases are obtained with a purity level exceeding 98%.
Claims19
A process for the production of a cation exchange diaphragm, wherein in a first stage of grafted copolymer powder is prepared by grafting styrene and/or its derivatives onto a polyethylene powder by exposing a suspension of said polyethylene and styrene and/or its derivatives to irradiation by means of ionizing rays so as to obtain a grafting degree of the monomers on the polyethylene polymer of 15 to 60%, in a second stage the grafted copolymer powder is brought into the form of a thin film by dissolving the grafted copolymer powder in an organic solvent, by pouring the thus obtained solution onto a support and then evaporating the solvent and in a third stage cation exchanger groups are fixed to the thus obtained grafted copolymer film.
A cation exchange diaphragm having an exchange capacity exceeding 0.5 milliequivalents per gram (meq/g) and preferably 1.75 meq/g, a resistivity below 100 .OMEGA..cm, preferably below 70.OMEGA..cm and a swelling in water exceeding 30% and preferably exceeding 60% compared with the dry mass, obtained by a process comprising:
- (a) preparing a grafted copolymer powder by exposing a suspension of a polyethylene powder in a solution of ethylenically unsaturated monomers consisting of styrene and/or one or more of its derivatives to irradiation by means of ionizing rays so as to obtain a grafting degree of the monomers on the polymer of 15 to 60%,
- (b) bringing into the form of a thin film the grafted copolymer powder by dissolving the grafted copolymer powder in an organic solvent, by pouring the thus obtained solution onto a support and then evaporating the solvent, and
- (c) fixing cation exchanger groups to the thus obtained grafted copolymer film.
Dependencies are inferred from the claim text.