GB1255483A - Polyamides - Google Patents

Abstract

1,255,483. Coated metal objects. B.P. CHEMICALS Ltd. 22 Oct., 1969 [18 Nov., 1968], No. 54590/68. Heading B2E. [Also in Division C3] Metal objects may be coated with a polyamide P by fluidized bed dip coating, electrostatic deposition, or flame-spraying. Polyamide. P comprises residues derived from: dicarboxylic acid(s) A containing #6 C-atoms; an acyclic polymethylene diamine B having 7-12 C-atoms in the chain, the chain bearing 1-3 alkyl substituents; and a cyclic diamine C such that its 2-dimensional structural formula does not possess an axis of symmetry passing through the amine groups. A may be one or more of e.g. adipic, sebacic, azelaic, or dodecanedioic acid, or an alkyl-substituted derivative thereof; tere- or isophthalic acid or hydrogenation products thereof; or phenylenediacetic acid. B may be 5-methylnonane diamine. C may be 3-aminomethyl-3,5,5-trimethylcyclohexylamine or m-xylylene diamine. Preferably C forms 10-40% moles of. the total diamine. Also present in P may be up to 20% moles of the total amine component of residues of, e.g. H 2 N-(CH 2 ) 6 -NH 2 , H 2 N- (CH 2 ) 12 -NH 2 , caprolactam, oenantholactam, or H 2 N-(CH 2 ) n -COOH where n is 5, 6, 10; or 11. P may be prepared by condensing, e.g. at 230-300‹C in the absence of free O 2 , the amines and the acid(s) A derivatives thereof, e.g. diesters or acid chlorides; e.g. by melt-polycondensation methods, e.g. simple diacid/ diamine condensation or condensation of the "nylon salt". A and the amines may be used in equimolar quantities or # 5% wt. excess of the amines may be used. The process may be performed in a twin-screw reactor. Also present may be a colour stabilizer, e.g. 0.001- 2.5% of ammonium hypophosphite, triphenylphosphite, diethyl hexylphosphite, or tris(nonylphenyl) phosphite. Acetic acid or monoamines may be added to control the M.W. of P. P preferably has viscosity >0.7. The Vicat softening point may be, e.g. 132.4‹C or 143‹C.