GB850215A - Improvements in or relating to thixotropic compositions - Google Patents

Abstract

A thixotropic heat-curable composition comprises (a) an amino-polyamide resin having an amine number greater than 50 and being the reaction product of an excess polyamine with polymeric fat acids, (b) an epoxy resin derived from a polyhydric phenol and a halohydrin and having an epoxy equivalency greater than 100, (c) a cation-modified clay flow control agent, (d) a polar organic compound as activator for the flow control agent, and (e) an inert filler. The relative proportions of the ingredients may vary from 30 to 70 parts of (a), 70 to 30 parts of (b), 20 to 40 parts of (c), 1 to 10 parts of (d) and 15 to 60 parts of (e). The polyamines employed to react with the polymeric fat acids preferably have the formula H2NR(NHR)nNH2, where R is alkylene and n is less than 6, e.g., diethylene triamine, triethylene tetramine, tetraethylene pentamine and di-1,3-propanetriamine. The polymeric acids are obtained by polymerizing drying and semi-drying oils or their free acids or esters thereof, and consist mainly of dimers and small quantities of trimers and higher polymers, particularly of linoleic acid. The flow control agents (c) are clays with an original base-exchange capacity of at least 25, in which the cation has been exchanged for an onium base to an extent sufficient to form an onium clay swelling to at least 10-fold in nitrobenzene, e.g. ammonium, phosphonium, oxonium, sulphonium, arsonium, stibonium and telluronium bases, and with a hydrophobic radical having a molecular area of at least 70 square angstrom units. They are described in U.S.A. Specification 2,531,427. Examples are dimethyl dioctadecyl ammonium bentonite, dimethyl "dicoco" ammonium bentonite, where "coco" refers to the hydrocarbon radicals derived from coconut fatty acids, and dimethyl dioctadecyl ammonium cation linked to a clay having primarily the formula MgO.4SiO2. 2H2O. The activator (d) causes the thickening and thixotropy and is preferably a hydroxy compound, e.g. ethyl alcohol, ethylene glycol monobutyl ether, glycerol, triethylene glycol, polyethylene glycol, lauryl alcohol and sorbitan esters and polyoxyalkylene sorbitan esters of fatty acids. Specified fillers, (e) are granular aluminium powder, iron powder, iron oxide powder, talc, alumina, powdered glass fibres, sintered nylon powder, clays such as kaolin; and other powdered metals, oxides, silicates and carbonates may be used. Uses: metal to metal bonding compositions, e.g. seam fillers, plastic solders, car body solders and caulking compositions, and for bonding non-metallic surfaces. Specification 850,216 also is referred to. Reference has been directed by the Comptroller to Specification 726,570.