Process for manufacturing a safety glass for motor vehicles and buildings, and product so obtained

Claim 1

A process for manufacturing safety glazing, formed of at least one glass sheet to which a plastic coating is bonded, which comprises: (1) preparing a coating composition which comprises: (a) a solution of polycaprolactone with molecular weight between 200 and 1200 and polyether with molecular weight between 250 and 1000, dissolved in an amount of between 10 and 40% of (b) a mixture of a vinyl monomer N-vinyl-2-pyrrolidone, with at least 10% and not more than 105% of a mono-, di-, tri- or tetra-acrylate monomer; (c) a photoinitiator in an amount between 0.5 and 3% of the total composition; (d) one or more silicone flow control agents or fluorinated flow control agents in an amount of 0.1 to 0.4%; (e) reaction catalyst in an amount of 0.02% to 0.4%; and (f) an aliphatic polyisocyante in an amount sufficient to react with an amount less than the stoichiometric amount of hydroxyl groups present in the initial part of the composition, with an -NCO index from 1.01 to 1.1, added immediately before use; (2) applying to a glass sheet the coating position with a viscosity between 40 and 200 centipoise immediately after preparation and before any significant change in viscosity caused by initiation of reaction between the hydroxyl and isocyanate groups in the composition; (3) immediately after applying the composition, spinning the glass sheet at about 10 to 50 rpm so as to ensure a constant thickness spread of the coating composition film over the entire surface of the sheet and to ensure that the thickness is kept constant at between 80 and 150 microns; (4) exposing the film to a high-intensity UV light source for a time sufficient to complete polymerization of the acrylic and vinyl monomers, and terminating the spinning of the sheet; and (5) heat-treating the coated glass sheet to complete formation of polyurethane from the hydroxyl and isocyanic groups of the polyisocyanates.