GB1055610A - Self-supporting polyamide film - Google Patents

Abstract

A self-supporting film is composed of a neutral thermoplastic polyamide derived from a polymerized fatty acid containing more than 80% dimer or a C1- 8 alkyl ester thereof. The fatty acid may be a saturated or mono- or poly-ethylenically or acetylenically unsaturated acid, e.g. oleic, linoleic, or tall oil fatty acid. It may be polymerized by the action of heat and/or a basic, Lewis acid or peroxide catalyst and may be hydrogenated before or after polymerization to reduce unsaturation. The ratio of oligomers in the product may be changed by fractional distillation. At dimer concentrations just above 80% the monomer/ trimer ratio must be within the region 1.8-1.2:1 but as the dimer concentration approaches 100% the monomer/trimer ratio becomes less critical. The polyamide may be produced by reacting the acid with a polyamine and/or an alkanolamine. The polyamine may be a C2- 20 alkylene diamine, e.g. 1,3-diaminopropane, 1,4 - diaminobutane, 1,6 - diaminohexane, 1,10 - diaminodecane, 1,12 - diaminododecane, 1,18 - diaminooctadecane, 1,4 - bis - (b - aminoethyl) benzene, 1,3- or 1,4-bis-(aminomethyl) cyclohexane, ethylene diamine, 1,2-diaminopropane, 3,4 - diethyl - 1,6 - diaminohexane, 3 - ethyl - 1,8 - diaminooctane, 2 - nonyl - 1,10-diaminodecane, or 2 - octyl - 1,4 - diaminoundecane. Alkanolamines may be of formula NH2R111OH where R111 is a C2- 8 alkylene radical, e.g. ethanolamine, propanolamine, butanolamine, 2-amino-3-hexanol, 2-amino-4-pentanol, 5-amino-4-octanol, or 3-amino-3-methyl-2-butanol. Where both polyamine and alkanolamine are used the ratio may be 1:0.05-2. For each mole of fatty acid used 0.05-0.5 mole of a di-carboxylic acid or ester of formula R11OCORCOOR11 may also be present in the reaction mixture where R is a C2- 20 hydrocarbon radical and R11 is H or a C1- 8 alkyl group. Acids of this type specified include adipic, sebacic and suberic acids. There may be overall a 10% excess of carboxyl groups over amino and hydroxyl groups or vice versa. The polymerization temperature may be 150-300 DEG C. Film of 3-5 mils thickness may be used to bond surfaces by heat-softening it in contact with the surfaces or subsequently cooling it until it hardens. A pressure of up to 15 p.s.i. may be used. The process may be used to seal the seams of metal containers, for sealing gaskets and for bonding paper and plastics.