Patent ID: 8540840

Claim:
A method of producing a model or tool comprising the sequential steps of: (a) mixing a first component containing a curable epoxy resin and a thixotropic agent with a second component containing a hardener system comprising at least one polyethyleneimine, at least one other amine having at least two amino hydrogen groups and a complex of a Lewis acid and a Lewis base having latent reactivity in a mix block to form a curable paste wherein the curable paste has a density of between 1.1-1.6 g/cm 3 ; (b) machine dispensing the curable paste on an outer surface of a substructure in the form of a continuous layer; (c) curing the continuous layer of curable paste at room temperature; (d) post-curing the layer of paste at a temperature of at least 50° C.; and (e) machining the cured continuous layer to produce the model or tool wherein the thixotropic agent comprises hydrophilic fumed silica, the Lewis acid is BX 3 AlX 3 , FeX 3 , FeX 2 , ZnX 2 , TiX 3 or TiX 4 where X independently represents a C 1-6 alkyl group, C 1-6 alkoxy group, hydrogen, bromine, iodine or fluorine atom provided that when the Lewis acid is BX 3 no X represents a fluorine atom, the Lewis base is ammonia or a compound of the formula Z(Ra) 3 in which Z is nitrogen or phosphorus and each Ra independently represents a hydrogen atom; an alkyl group having from 1 to 20 carbon atoms optionally substituted by one or more phenyl groups in which each phenyl group may be optionally substituted by one or more C 1-12 alkyl groups and/or halogen atoms; a phenyl group optionally substituted by one or more C 1-12 alkyl groups and/or halogen atoms; a C 5-7 cycloalkyl group; or two Ra's together represent an alkylene group having from 4 to 6 carbon atoms one or more of which may be replaced by an oxygen or a sulphur atom and the curable paste after curing has a heat deflection temperature above 100° C.