Patent GB-1024396-A (GB)
Title: Process for curing polyepoxides by polymercaptans and accelerators, and resulting products
IPC: C04B41/48
Filed: 1964-06-18
Abstract: A polyepoxide is cured by mixing it with a polymercaptan and applying it to a surface, and applying separately thereto an acclerator for the cure.  The two components may be applied in either order, or simultaneously from different vessels.  Pigments, fillers, dyes, plasticizers, and extenders may be included, and solvents or diluents including monoepoxy compounds may be used. The accelerator is preferably applied as a solution containing 1-80% by weight of the accelerator, in amount providing 0.1-5% of accelerator by weight of resin.  The ratio of polymercaptan to resin is preferably at least 0.8:1.  Cure occurs at room temperature but may be hastened by heating to 15-150 DEG  C. if desired.  Suitable polyepoxides are glycidyl ethers of polyhydric phenols, e.g. diphenylol alkanes, diphenylol sulphone, resorcinol, hydroquinone, dihydroxydiphenyl, and dihydroxynaphthalenes, and phenol-formaldehyde condensates, and of aliphatic polyhydroxy compounds, e.g. glycerol, ethylene glycol and trimethylol propane, and poly-(epoxyalky) esters of polycarboxylic acids and polymerized unsaturated acids, and epoxidized unsaturated acid esters and dienes, and di-(epoxyalkyl) ethers, and e.g. 3,4-epoxy-6-methyl - cyclohexylmethyl 3,4 - epoxy - 6 - methyl-cyclohexane carboxylate.  Glycidyl polyethers of 2,2-bis-(4-hydroxyphenyl) propane of molecular weight 340-4000 are preferred. The polymercaptans preferably contain more than two mercapto groups per molecule and may be mercapto-hydrocarbons, esters, ethers, urethanes, and suphides, e.g. glycerol and hexane 1,2,6-triol trithioglycollates and pentaerythritol tetrathioglycollate, glycerol tri-(mercaptobutyl ether), tri-(mercaptoethyl) trimellitate, or products of the reaction between H2S and any of the above polyepoxides, notably polyglycidyl ethers of polyhydric alcohols and phenols.  In particular, compounds containing heterocyclic rings substituted by at least three mercaptoalkyl groups are useful, e.g. 2,4,6-tri 1 (2 - mercaptoethyl) - 1,3,5 - trioxane. The accelerators include phenols, sulphides, tertiary amines, organic phosphines and arsines and antimony compounds, amine salts, and quaternary ammonium salts (long list).  In Example I a bisphenol-A-based epoxy resin containing butyl glycidyl ether is mixed with a polymercaptan from H2S and a novolac polyglycidyl ether in solution, spread on a metal surface, and sprayed with benzyl dimethylamine solution. In Example II titanium-calcium pigment, diatomaceous silica and calcium carbonate are added as a pigment to the mixture as in I.  In Examples III, IV and X other curing agents, and in V, IX and XI other accelerators are used, selected from the above lists.  Uses.-Non-skid road coatings, coatings for loading + storage areas, factory floors and storage tanks; painting ships + car parts; lamination; filament winding; encapsulation.ALSO:Surfaces (e.g. roads and floors, wires) may be coated by applying thereto in separate applications (1) a mixture of a polyepoxide and a polymercaptan curing agent, and (2) an accelerator for the cure (see Division C3).  The reagent (1) may be applied directly, if liquid, or in molten form or in solution while (2) maybe applied as a solution, or, preferably, in solution.  The reagents may be applied in either order, or the separate solutions may be applied simultaneously by spraying.