Patent GB-923085-A (GB)
Title: Improvements in or relating to adhesives
IPC: C09J175/06
Filed: 1959-06-19
Abstract: An adhesive comprises a solution in a volatile organic solvent of (i) 100 parts by weight of a reaction product resulting from the reaction of a polyester resin having more than one active hydrogen group with diisocyanate in the proportion of from about 0,9 to about 1,4 mols. of diisocyanate to 1 mol. of the polyester resin, (ii) a tackifying resin compatible with the reaction product, and (iii) from about 5 to about 15 parts by weight of polyisocyanate, together with from about 30 to about 60 parts by weight of a mineral filler mixture comprising from about 10 to about 25 parts by weight of fibrous magnesium silicate, from about 15 to about 35 parts by weight of finely divided calcium silicate and from about 5 to about 20 parts by weight of finely divided, substantially iron-free silica.  In a modification the adhesive is made up in two parts, part A comprising the solvent, components (i) and (ii) and the mineral filler mixture and part B comprising a solution of arylene polyisocyanate, wherein the quantity of part B mixed with part A to provide a curing adhesive is sufficient to provide about 5 to about 15 parts by weight of polyisocyanate to 100 parts by weight of the reaction product. Maleic acid or anhydride (0,25 to 5 parts by weight) may also be incorporated in the mixture to prevent increase of viscosity on storage.  Suitable polyesters are those obtained from adipic, succinic, sebacic, maleic or azelaic acids and ethylene, propylene, diethylene, triethylene or butylene glycols, with possibly a small proportion of trimethylol propane. As tackifying resins there are specified chlorinated polyphenyls, alkali-catalysed p-substituted phenol aldehyde resin or epoxy resins.  The latter may be derived from epichlorhydrin and bisphenol, hydroquinone or resorcinol, or may be a complex epoxide obtained by reacting polyhydric phenols with simpler epoxides such as the epichlorhydrin reaction product of glycerol or trimethylolpropane.  Suitable solvents are ethyl acetate, ethylene glycol monoethyl ether acetate, acetone or methyl ethyl ketone, with up to 15% of toluene.  Preferred polyisocyanates are polymethylene polyphenyl isocyanates, though diphenyl methane diisocyanate, triphenyl methane triisocyanate and aliphatic polyisocyanates are also mentioned.  In examples the adhesives comprise (1) part A: a reaction product of tolylene diisocyanate with an adipic acid/butylene glycol polyester, finely divided calcium silicate and fibrous magnesium silicate which were compounded in a mill and added to iron-free fluffy silica in ethyl acetate, followed by a glycidyl ether polyepoxide resin and maleic acid; part B: polymethylene polyphenyl isocyanate in ethyl acetate and o-dichlorobenzene.  A mixture of A and B is used for attaching a polychloropene shoe sole to a leather upper; (2) a similar mixture but a chlorinated terphenyl replaces the epoxy resin in part A; (3) a similar mixture, but with the use as part B of diphenylmethane-4,41-diisocyanate and polymethylene phenyl isocyanate dissolved in ethyl acetate and dichlorobenzene; (4) part A: the polyester/tolylene diisocyanate reaction product as in (1), calcium silicate, fibrous magnesium silicate, fluffy iron-free silica, toluene, ethyl acetate and chlorinated polyphenyl resin; part B: a reaction product of phenol and polymethylene phenyl isocyanate dissolved in methyl ethyl ketone.