Cooking item comprising a non stick coating with improved properties of adhesion to the substrate

摘要

A cooking item including a vitreous coating with improved impact-resistance properties, and a method for manufacturing such an item. The method for manufacturing includes optionally treating a concave internal side of a substrate having the end shape of the cooking item, the concave internal side being arranged on the side of the food to be introduced in said item, and a convex exterior side to be arranged on the heat source side, so as to obtain a treated internal side adapted to cause a hard base layer to adhere to the substrate, The method further includes preparing an adhering hard base layer on said internal side of the substrate, be it treated beforehand or not, and preparing a non-stick coating on the hard base layer.

主权项

1. A method for producing a cooking item, the method comprising:
a) providing a substrate having an end shape of the cooking item, the end shape presenting a concave internal side configured to contain a food item introduced into said cooking item, and a convex exterior side configured to be positioned proximate a heat source; b) optionally, treating the internal side of the substrate, so as to obtain a treated internal side adapted to cause a hard base layer to adhere to the substrate; c) preparing a discontinuous enameled adhering base layer on said internal side of the substrate, be it treated beforehand or not; and d) preparing a non stick PTFE-free coating on said hard base layer formed in step c); wherein step c) of preparing a discontinuous, enameled hard base layer comprises successively— c1) preparing an aqueous slurry of enamel frit, c2) applying, through air spraying, the slurry on the internal side of the substrate with a pressure equal to or higher than 4 bars such that the amount of deposited slurry is comprised between 0.07 g/dm2 and 0.2 g/dm2, and then c3) drying and/or curing said enamel layer so as to form a hard biscuit of enamel or a layer of cured enamel, and wherein step d) of preparing the non stick PTFE-free coating on said enamel hard biscuit or said cured enamel layer comprises successively— d1) preparing a sol-gel composition (A+B) comprising at least a colloidal metal oxide and at least a metal oxide precursor, wherein the preparation of the sol-gel composition (A+B) comprises successively:
i) preparing an aqueous composition A comprising 5 to 30% by weight with respect to a total weight of the aqueous composition A of at least one colloidal metal oxide, and 0 to 20% by weight with respect to a total weight of composition A of a solvent comprising at least one alcohol;ii) preparing a solution B comprising at least a metal alkoxide as the at least one metal oxide precursor;iii) mixing solution B of metal alkoxide with aqueous solution A so as to obtain a sol-gel composition (A+B) containing 40 to 75% by weight of the aqueous composition A with respect to a total weight of the sol-gel composition (A+B), so that an amount of colloidal metal oxide represents 5 to 30% by weight of the sol-gel composition (A+B) on a dry basis; d2) applying over an entirety or over a portion of the enamel hard biscuit or said cured enamel layer at least a layer of the sol-gel composition (A+B) having a wet-basis thickness of at least 20 μm, and then d3) curing said sol-gel composition layer (A+B) so as to obtain a non stick PTFE-free vitreous coating having a thickness of at least 10 μm.