Patent GB-478588-A (GB)
Title: Improvements in coated articles
IPC: B05D7/16
Filed: 1936-07-20
Abstract: A primer coating-composition which will adhere firmly to metal, and which, after hardening, will firmly hold an overcoating of vinyl resins carried in a ketonic solvent, comprises a phenol-aldehyde, alkali catalyst type, condensation resin, having its condensation process arrested before a solid resin has been formed, dissolved in a high-boiling solvent and blended with another resin having the property of adherence to metal. Specified high-boiling solvents are phenol, cresol, cresylic acid, cyclohexanone, cyclohexanol and benzyl alcohol, and a low-boiling solvent also may be present in the blend of resins.  Specified resins for blending with the phenol-aldehyde resin are Kauri gum, phthalic anhydride-glycerol-fatty acid resins and Vinsol Resin No. 1, and plasticizers such as linseed oil fatty acids, wood oil acids and butyl acetyl ricinoleate may be added. According to an example, a resin, formed by condensing commercial cresol with formaldehyde in the presence of sodium hydroxide, the condensation being arrested before a solid resin is formed, is dissolved in a high-boiling solvent, with or without a low-boiling solvent such as alcohol or ethyl acetate, and to this varnish are added a xylol solution of a phthalic anhydride-glycerol resin and a plasticizer.ALSO:A metallic object is provided with an adherent coating of a polymerized, thermoplastic, vinyl resin comprising essentially the conjoint polymer of vinyl chloride and a vinyl ester of a lower fatty acid, by first coating the object with a liquid containing a phenol-aldehyde, alkali catalyst type, condensation resin, having its condensation process arrested before a solid resin has been formed, dissolved in a high boiling solvent and blended with another resin having the property of adherence to metal, hardening said applied coating, e.g. by heating to 140 DEG  C., and then applying another coating containing said vinyl resin in solution in a ketonic solvent such as acetone.  Specified high boiling solvents for the phenol-aldehyde resin are phenol, cresol, cresylic acid, cyclohexanone, cyclohexanol and benzylalcohol, and a low boiling solvent, such as ethyl alcohol, may also be present in the blend of resins.  Specified resins for blending with the phenol-aldehyde resin are the kauri gum resins, phthalic anhydride-glycerol-fatty acid resins, which may be added dissolved in xylol, and Vinsol Resin No. 1, and plasticizers such as linseed oil fatty acids, wood oil acids and butyl acetyl ricinoleate may be added.  According to an example, a resin, formed by condensing commercial cresol with formaldehyde in the presence of sodium hydroxide, the condensation being arrested before a solid resin is formed, is dissolved in a high boiling solvent such as phenol, cresol, cyclohexanone, cyclohexanol or benzyl alcohol, with or without the addition of a low boiling solvent such as alcohol or ethyl acetate.  To this varnish is added a solution of a phthalic anhydride-glycerol type resin in xylol, and a plasticizer, and the mixture is applied to a metallic surface and baked to harden the resinous film.  The vinyl resin solution is then applied.