GB952590A - Pressure-sensitive adhesives - Google Patents

Abstract

A pressure-sensitive adhesive comprises a monopolymer of a C1-C14 alkyl acrylate or methacrylate or a copolymer in which such an ester represents a major weight proportion, cross-linked by an oxide, hydroxide or salt of a polyvalent metal which is a metal of Group II or the transitional series of elements, e.g. calcium hydroxide, calcium stearate, zinc chloride, zinc oxide, zinc stearate, zinc resinate, managanese resinate and cobalt naphthenate. The cross-linking reaction may be accelerated by polyamines and polyalcohols, e.g. polyethylene imine, tetraethylene pentamine, tris (dimethylaminomethyl) phenol, polyethylene glycol, polypropylene glycol, glycerol, sorbitol and mannitol. The curing of the adhesive is effected by heat, e.g. at 150-200 DEG C. The uncured adhesive may be applied in the form of a solution or aqueous dispersion on to a backing, on which it is then cross-linked. Solvents specified for the adhesive are benzene, toluene, hexane, heptane, carbon tetrachloride and chloroform. The examples describe the following procedures: (1) a solution of polybutyl acrylate, polybutyl methacrylate and zinc stearate in toluene is applied to aluminium foil and heated to 200 DEG C. for 2 minutes; (2) as in (1) but employing as the cross-linking agent a solution of zinc chloride and tris (dimethylaminomethyl) phenol in acetone; (3) as in (1) but employing zinc resinate as the cross-linking agent and applying the adhesive to a polytetrafluoroethylene film; (4) a toluene solution containing polydodecyl methacrylate, manganese resinate and tetraethylene pentamine is applied to aluminium foil, and the coating heated to 200 DEG C.; (5) zinc resinate and polyethylene glycol are added to an aqueous emulsion of a 2-ethylhexyl acrylate/vinyl acetate copolymer; and the resulting composition is coated on a polyester film and heated to 150 DEG C.; (6) a toluene solution containing an ethyl acrylate/2-ethylbutyl acrylate copolymer and cobalt naphthenate is applied to aluminium foil, and the coating heated to 200 DEG C.; and (7) a toluene solution containing polybutyl acrylate, hydrogenated ester gum, calcium hydroxide and mannitol is applied to aluminium foil, and the coating is heated to 200 DEG C.ALSO:Pressure-sensitive adhesive tapes and sheets are made by applying to a backing material an adhesive comprising a homopolymer of a C1-C14 alkyl acrylate or methacrylate or a copolymer in which such an ester represents a major weight proportion, together with a cross-linking agent for the polymer which is an oxide, hydroxide or salt of a metal of Group II or the transitional series of elements, and then cross-linking the adhesive on the backing by means of heating. Also present in the adhesive may be a polyamine or polyalcohol as a curing accelerator. The backing material may be aluminium or copper foil or a film made from polyester or polytetrafluoroethylene. The examples describe the following pressure-sensitive adhesive assemblies: (1) aluminium foil coated with a mixture of polybutyl acrylate and polybutyl methacrylate cross-linked by zinc stearate; (2) as in (1), but with zinc chloride and tris(dimethylaminomethyl) phenol used as cross-linking agents; (3) polytetrafluoroethylene foil coated with the polymer mixture of (1) cross-linked with zinc resinate; (4) aluminium foil is coated with polydodecyl methacrylate cross-linked by manganese resinate and tetraethylene pentamine; (5) polyester film is coated with a copolymer of 2-ethylhexyl acrylate and vinyl acetate cured with zinc resinate; (6) aluminium foil is coated with a copolymer of ethyl acrylate and 2-ethylbutyl acrylate cured with cobalt naphthenate; and (7) aluminium foil is coated with a mixture of polybutyl acrylate and hydrogenated ester gum cured with calcium hydroxide and mannitol. In Example (5) the adhesive is applied to the backing in the form of an aqueous emulsion, in all the other examples the adhesive is applied as a solution in toluene.