Patent GB-871078-A (GB)
Title: Polymeric oxidation products of phenols
IPC: C09D5/44
Filed: 1957-11-08
Abstract: Polymeric products are deposited at the anode when a phenol which (1) retains its benzenoid structure when partially oxidized and (2) has at least two unsubstituted positions in the aromatic ring, these positions being ortho and/or para to the hydroxyl group, is subjected to a unidirectional electric current in a substantially non-aqueous electrolytic bath.  In the preferred case the anode is a metal other than Pb or Sn and the polymer is deposited as a film on the metal provided that the phenol does not have a tertiary alkyl carbon atom in the ortho position.  Phenols specified are phenol, o-chlorophenol, o-hydroxy-diphenyl, 3,5-xylenol, m-cresol, m-dihydroxybenzene, 3-methyl,-5-ethyl phenol, p, p1-dihydroxy diphenyl, p-tert. amyl phenol, p-tert. butyl phenol, 2, 5-xylenol, bisphenol A, p-phenyl phenol, a -naphthol, and 1, 7-dihydroxynaphthalene.  The phenol may be in molten condition, or dissolved in a substantially nonaqueous solvent, e.g. methanol, ethanol, ethylene glycol, glycerol, nitrobenzene, dimethylformamide, acetone, and mixtures thereof. There may be added to the bath (a) flexibilizing agents, e.g. o-cresol, m-cresol, cyclohexanol, furfuryl, benzyl, n-hexyl or allyl alcohols, and esters of mono- or di-hydric aliphatic alcohols containing up to 4C with an aliphatic fatty acid containing at least 9C; (b) alkaline electrolytes e.g. Na, K or Li hydroxides, Na or Li acetates, and Na carbonate, phosphate or borate or (c) urea.  Graphite is the only cathode specified, but the anode may be Fe, Cu or Zn, or alloys thereof e.g. cast iron, wrought iron, steel, or the Fe/Zn alloy formed by sherardizing Zn on a ferrous base.  Several examples are given at the end of which there is discussed the case in which phenol is electrolysed at a metal anode in the presence of 2%-5% p-cresol: in this case the polymeric product is not a film but a flaky solid which may be mixed with silicone-alkyds to form coating materials. Uses: As coatings on metal sheets, plates, cans, tanks, kettles or pipes for chemical or foodstuff purposes.ALSO:Coatings may be produced on the surface of an article of a metal other than Pb or Sn by (a) immersing the article in a substantially non-aqueous electrolytic bath containing a phenol having at least two unsubstituted positions in the aromatic ring, the said positions being ortho and/or para to the phenolic hydroxyl group of the phenol, and not having a tertiary alkyl carbon atom linked to the aromatic ring in the ortho position, the phenol retaining its benzenoid structure when partially oxidized, and (b) passing a unidirectional electric current through the bath and through the metal article acting as an anode to cause the phenol to oxidize partially, polymerize, cross-link and be deposited as an adherent polymeric film upon the article.  A list of suitable phenols is given.  The phenol may be in molten condition, or dissolved in a substantially non-aqueous solvent, e.g. methanol, ethanol, ethyleneglycol, glycerol, nitrobenzene, dimethylformamide, acetone and mixtures thereof.  There may be added to the bath (i) flexibilizing agents, e.g. o-cresol, m-cresol, cyclohexanol, furfuryl, benzyl, n-hexyl or allyl alcohols, and esters of mono- or dihydric aliphatic alcohols containing up to 4 C with an aliphatic fatty acid containing at least 9 C, (ii) alkaline electrolytes, e.g. Na, K or Li hydroxides, Na or Li acetates, and Na carbonate, phosphate or borate, or (iii) urea. The anode may be Fe, Cu, or Zn, or alloys thereof, e.g. cast iron, wrought iron, steel, or the Fe/Zn alloy formed by sherardizing Zn on a ferrous base and may be in the form of sheets, plates, cans, tanks, kettles or pipes for chemical or foodstuff purposes.  Examples are given.