Cooking utensil comprising a hard base made from ceramic and/or metal and/or polymer material and a nonstick coating containing a fluorocarbon resin

Abstract

The invention relates to a cooking utensil comprising a hollow bowl with a base and a side wall rising from the base, and including at least one fragile area. The bowl has a concave inner surface for receiving food, as well as a convex outer surface. The utensil is coated successively, from the bowl, with a hard base and a nonstick coating, which covers the hard base and includes at least one layer containing at least one fluorocarbon resin. The hard base has a layer that is at least broken at the fragile area. The invention also relates to a method for producing such a utensil.

Claims

1. A method for producing a cooking utensil, comprising the following steps: a) supplying a metal support in the form of a disk; b) forming said metal support to give it the shape of a bowl, including a bottom, side walls rising from the bottom and having at least one fragile area, the at least one fragile area being the connection area between the bottom and side walls, a concave inner surface adapted to receive food, and a convex outer surface; c) adhering a hard base on said inner surface of the support, wherein adhering the hard base comprises: thermal spraying a ceramic and/or metal and/or polymer material having a powdery form on said inner surface of the bowl to form a layer which is at least discontinuous on the at least one fragile area, the discontinuous layer having the form of a superficial dispersion of drops of said material distributed in a substantially homogeneous manner on said inner surface at least at the location of the at least one fragile area, with: an overlap ratio which is between 30% and 80% of the surface to be covered, and a drop size between 2 m and 50 m, and wherein the hard base has a surface roughness (Ra) between 2 m and 12 m; d) adding a nonstick coating on said hard base, wherein the nonstick coating comprises at least one layer including at least one fluorocarbon resin, alone or in a mixture with at least one resistant thermostable bonding resin at least at 200 C., with the resin or resins forming a sintered continuous network.

2. The method according to claim 1, wherein the thermal spraying is a flame spraying.

3. The method according to claim 2, wherein the material to be sprayed is a powdery material having a granulometry from 5 m to 65 m.

4. The method according to claim 3, wherein the powdery material has a granulometry of 20 m to 45 m.

5. The method according to claim 1, wherein adhering the hard base is preceded with a step of preheating of said metal support if step b) is performed before adhering the hard base or preheating said bowl if step b) is performed after adding said nonstick coating.

6. The method according to claim 1, comprising a further step of treating the inner surface of the support to obtain a treated inner surface that will allow the adherence of a hard base on the support before the step c) of adhering the hard base on said inner surface of the support is performed.

7. The method according to claim 1, wherein the step d) of adding the nonstick coating comprises a step of depositing on said hard base the at least one fluorocarbon resin, and a step of sintering.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) Other advantages and particularities of this invention shall result from the following description, provided by way of a non-restricted example and made in reference to the annexed figures:

(2) FIG. 1 shows a diagrammatical cross-section view of a cooking utensil in accordance with the invention according to a first alternative,

(3) FIG. 2 shows a diagrammatical cross-section view of a cooking utensil in accordance with the invention according to a second alternative, and

(4) FIG. 3 shows a diagrammatical cross-section view of a cooking utensil in accordance with the invention according to a third alternative.

DETAILED DESCRIPTION OF THE INVENTION

(5) The identical elements shown in the FIGS. 1 and 2 are identified by identical numerical references.

(6) FIGS. 1 to 3 show, by way of example of a cooking utensil according to the invention, a frying pan 1 comprising a metal support 2 having the form of a hollow bowl and a grasping handle 5. The support 2 comprises an inner surface 24 which is the surface oriented towards the side of the food able to be received in the frying pan 1, and an outer surface 25 which is intended to be arranged towards an external heat source.

(7) The inner surface 24 is coated successively, from the support 2, with a hard base 3 in accordance with this invention, and with a nonstick coating 4 which successively includes from the hard base 3 a bonding primer layer 41 and two top layers 42, 43.

(8) Moreover, FIGS. 1 to 3 also show that the outer surface 22 of the support 2 is advantageously coated with an exterior covering coating 6 (for example with glaze), the thickness of this covering coating 6 being conventionally between 20 m and 300 m.

(9) In the alternative embodiment shown in FIG. 1, the hard base 3 is entirely discontinuous (over the entire inner surface 24 of the support 2) comprising a superficial dispersion of drops 31 of a ceramic and/or metal and/or polymer material (such as defined hereinabove). These drops are solidified and have an average size between 2 m and 50 m and are distributed homogeneously on the surface of the inner surface 21, with an overlap ratio of the inner surface between 40 and 80%, with a surface density between 300 drops/mm.sup.2 and 2000 drops/mm.sup.2.

(10) In this alternative embodiment, the drops of the ceramic and/or metal and/or polymer material 31 dispersed on the surface of the inner surface 24 are embedded in the primary layer 41 of the nonstick coating 4, in such a way as to allow for the bonding of the primary layer to the hard base 3. Such a hard base 3 leads to an increased mechanical reinforcement of the nonstick coating 4, particularly in terms of hardness and of adherence to the underlying hard base 3. Indeed, the particles of sintered fluorocarbon resin and the fillers of the primary layer 41 by penetrating between the drops of the solidified ceramic and/or metal and/or polymer material 31 deposited on the surface of the inner surface 24, reinforce the adherence of the primary layer 41 on the hard base 3. Therefore, the mechanical reinforcement of the nonstick coating 4 is increased thanks to the fillers in the primary layer 41 as well as to the dispersion of drops 31 of the hard base 3 which play a role analogous to that of a reinforcing filler in the interpenetration area of the two layers 3, 41.

(11) In the alternative embodiment shown in FIG. 2, the hard base 3 is a continuous layer of ceramic and/or metal and/or polymer material on the bottom 21 and discontinuous on the connection area 23 between the bottom 21 and the side walls 22, and on the side walls 22.

(12) Such a combination can be advantageously obtained by adjusting the spraying times according to the zones intended to be covered with a deposit that is either continuous or discontinuous, i.e. by having a slow displacement of the torch in the non-fragile areas (in order to form a continuous hard base area) and a fast displacement in the fragile areas (in order to form a discontinuous hard base area).

(13) In the alternative embodiment shown in FIG. 3, the hard base 3 is a continuous layer of ceramic and/or metal and/or polymer material on the bottom 21 and on the connection area 23 between the bottom 21 and the side walls 22, and discontinuous on the side walls 22.

EXAMPLES

(14) Operating Procedure

(15) Equipment: CASTOLIN DS 8000 torch with nozzle diameter 30 mm Twin 20 Sulzer-Metco powder dispenser Gas propellant: argon or air 4 Nl/min Combustible gas: acetylene 14 Nl/min Oxygen 31 Nl/min Temperature of the support during the application of the hard base: greater than or equal to the ambient temperature (of a magnitude of 20-25 C.) and preferably greater than or equal to 200 C. for a ceramic powder Spraying time: from 0.5 to 20 s for a frying pan 26 cm in diameter Application of the PTFE: via gun spraying (with a roller or via screen printing)
Tests
Evaluation of the Resistance to Abrasion

(16) The resistance to abrasion of the nonstick coating formed is evaluated by subjecting the latter to the action of an abrasive pad of the green SCOTCH BRITE (registered trademark) type.

(17) The resistance to abrasion of the coating is estimated quantitatively by the number of passages of the pad that are required to create the first scratch (corresponding to the appearance of the metal that constitutes the support).

(18) The anti-adherence is measured according to the more or less easy cleaning of the carbonized milk. The scoring is as follows: 100: means that the film of carbonized milk is fully eliminated by the simple application of a stream of water from the kitchen faucet; 50: means that circular movements of the object must be added under the stream of water in order to completely delaminate the carbonized film; 25: means that it is necessary to soak for 10 minutes and possibly force the departure by passing a wet sponge in order to completely eliminate the film; 0: means that at the end of the preceding process, all or a portion of the carbonized film remains adherent.
Evaluation of the Adherence

(19) The adherence of the nonstick coating on the hard base is also evaluated. For this, a test of adherence by surface grid is carried out according to ISO standard 2409, followed by an immersion of the utensil for 9 hours (via 3 three-hour cycles in boiling water). Then, it is observed whether or not the nonstick coating has a delamination.

(20) The scoring is as follows: no square must be delaminated in order to obtain a score of 100 (excellent adherence); in case of delamination the value measured is equal to 100 minus the number of delaminated squares.

Example 1

(21) Cooking Utensil According to the Invention with a Discontinuous Ceramic Hard Base

(22) An aluminum disk 3003 of diameter 330 mm is degreased then brushed in order to obtain a roughness Ra of 1.5 m. This disk is preheated to a temperature between 150 C. and 200 C.

(23) The torch is used to apply a ceramic powder constituted of an alumina/titanium dioxide mixture (at the rate of 87% alumina and 13% titanium dioxide) in order to obtain a discontinuous deposit across the entire surface of 1.5 g and a roughness of 4 m.

(24) This disk prepared as such is successively covered with a primary layer and a top layer with a PTFE base.

(25) After baking at 415 C., the disk prepared as such is stamped in order to produce a bowl with a bottom of diameter 26 cm, interiorly coated with PTFE (nonstick coating).

(26) This coating does not have any cracks, or losses of adhesion.

(27) After an aging of three 3-hour cycles in contact with boiling water, the adherence measured using a surface grid is equal to 100%.

(28) This type of bowl is also tested for its resistance in the dishwasher, after 20 washing cycles, the coating does not have any cracks or blisters.

(29) An abrasion test is also carried out via back and forth passages with an abrasive pad. After 20,000 passages, the coating does not have any scratches in the metal and its anti-adherence measured by the cleaning of the carbonized milk is 50.

Example 2

(30) Cooking Utensil According to the Invention with a Discontinuous Ceramic Hard Base

(31) An aluminum bowl 3003 of diameter 260 mm is degreased and sandblasted in order to obtain a roughness Ra of 2 m. This bowl is preheated to a temperature between 150 C. and 200 C.

(32) The torch is used to apply a ceramic powder of the alumina/titanium dioxide type (87%/13% respectively) in order to obtain a discontinuous deposit of 0.9 g and a roughness Ra of 3.5 m.

(33) After cooling this bowl prepared as such is successively covered with a primary layer and a top layer with a PTFE base.

(34) The coating is sintered at a temperature of 415 C. for 7 minutes.

(35) After cooling, the coating does not have any cracks, or losses of adhesion.

(36) After an aging of three 3-hour cycles in contact with boiling water, the adherence measured using a surface grid is equal to 100%.

(37) This type of bowl is also tested for its resistance in the dishwasher: after 20 washing cycles, the coating does not have any cracks or blisters.

(38) This type of bowl is also subjected to the same abrasion test as in example 1. After 20,000 passages, the coating does not have any scratches in the metal and its anti-adherence measured by the cleaning of the carbonized milk is 100.

Example 3

(39) Multilayer Cooking Utensil According to the Invention with a Discontinuous Ceramic Hard Base

(40) A multilayer bowl of diameter 260 mm, associating an outer sheet made of ferritic steel of thickness 0.5 mm, an intermediary sheet made of aluminum 3003 of thickness 2 mm and an outer sheet made of austenitic stainless steel of thickness 0.5 mm, is degreased and microblasted (on the inner sheet) in order to obtain a roughness Ra of 1.3 m. This bowl is preheated to a temperature between 150 C. and 200 C.

(41) The torch is used to apply a ceramic powder of the alumina/titanium dioxide type (87%/13% respectively) in order to obtain a discontinuous deposit of 1.2 g and a roughness Ra of 3 m.

(42) After cooling, this bowl prepared as such is successively covered with a primary layer and a top layer with a PTFE base. The coating is sintered at a temperature of 415 C. for 7 minutes, then cooled.

(43) After cooling, the coating does not have any cracks, or losses of adhesion.

(44) After an aging of three 3-hour cycles in contact with boiling water, the adherence measured using a surface grid is equal to 100%.

(45) This type of bowl is also tested for its resistance in the dishwasher, after 20 washing cycles, the coating does not have any cracks or blisters.

(46) This type of bowl is also subjected to the same abrasion test as in examples 1 and 2. After 20,000 passages, the coating does not have any scratches in the metal and its anti-adherence measured by the cleaning of the carbonized milk is 100.

Example 4

(47) Multilayer Control Cooking Utensil with a Discontinuous Hard Base with Glaze

(48) A multilayer control bowl of diameter 260 mm, associating an outer sheet made of ferritic steel of thickness 0.5 mm, an intermediary sheet made of aluminum 3003 of thickness 2 mm and an outer sheet made of austenitic stainless steel of thickness 0.5 mm, is degreased and microblasted in order to obtain a roughness Ra of 1.3 m. Gun spraying is used at ambient temperature to apply a glaze slip for steel with a softening point 720 C. in such a way as to obtain a discontinuous deposit of 1.2 g and of roughness 3 m.

(49) This bowl is baked at 750 C. in order to obtain the gelation of the glaze. At this temperature, the complete delamination of the multilayer bowl is observed.

Example 5

(50) Control Cooking Utensil with a Continuous Hard Base Made of Ceramic

(51) An aluminum disk 3003 of diameter 330 mm is degreased then brushed in order to obtain a roughness of 1.5 m.

(52) The torch is used to apply a ceramic of the alumina/titanium dioxide type (87%/13% respectively) in order to obtain a continuous deposit of 8 g and a roughness of 8 m over the entire bowl i.e. on the fragile and non-fragile areas.

(53) This disk prepared as such is successively covered with a primary layer and a top layer with a PTFE base.

(54) After baking at 415 C., the disk is stamped in order to produce a bowl of diameter 26 cm coated interiorly.

(55) At stamping, a fracture of the hard base is observed in the folding areas and the coating has many cracks and losses of adherence.

(56) After an aging of three 3-hour cycles in contact with boiling water, the adherence, measured using a surface grid, is equal to 0%.

Example 6

(57) Cooking Utensil According to the Invention with a Discontinuous Metal Hard Base

(58) An aluminum bowl 3003 of diameter 260 mm is degreased and sandblasted in order to obtain a surface roughness Ra of 2 m. This bowl is preheated to 150 C.

(59) The torch is used to apply an aluminum alloy powder 4917 in order to obtain a discontinuous deposit of 1 g and a roughness of 3.5 m.

(60) After cooling this bowl prepared as such is successively covered with a primary layer and a top layer with a PTFE base.

(61) The coating is sintered at a temperature of 415 C. for 7 minutes.

(62) After cooling, the coating does not have any cracks, or losses of adhesion.

(63) After an aging of three 3-hour cycles in contact with boiling water, the adherence measured using a surface grid is equal to 100%.

(64) This type of bowl is also tested for its resistance in the dishwasher: after 20 washing cycles, the coating does not have any cracks or blisters.

(65) This type of bowl is also subjected to the same abrasion test as in example 1. After 20,000 passages, the coating does not have any scratches in the metal and its anti-adherence measured by the cleaning of the carbonized milk is 100.

Example 7

(66) Cooking Utensil According to the Invention with a Discontinuous Metal Hard Base

(67) An aluminum bowl 3003 of diameter 260 mm is degreased and sandblasted in order to obtain a surface roughness Ra of 2 m. This bowl is preheated to 200 C.

(68) The torch is used to apply a stainless steel 304 LHD powder (granulometry +150 0.6%; 45 43%: granulometry obtained by screening giving 0.6% of the particles greater than 150 m and 43% less than 45 m) containing 11.6% Ni and 19% Cr in order to obtain a discontinuous deposit of 1.1 g and a roughness Ra of 3.2 m.

(69) After cooling this bowl prepared as such is successively covered with a primary layer and a top layer with a PTFE base.

(70) The coating is sintered at a temperature of 415 C. for 7 minutes.

(71) After cooling, the coating does not have any cracks, or losses of adhesion.

(72) After an aging of three 3-hour cycles in contact with boiling water, the adherence measured using a surface grid is equal to 100%.

(73) This type of bowl is also tested for its resistance in the dishwasher: after 20 washing cycles, the coating does not have any cracks or blisters.

(74) This type of bowl is also subjected to the same abrasion test as in example 1. After 20,000 passages, the coating does not have any scratches in the metal and its anti-adherence measured by the cleaning of the carbonized milk is 100.

Example 8

(75) Cooking Utensil According to the Invention with a Discontinuous Polymer Hard Base

(76) An aluminum disk 3003 of diameter 330 mm is degreased then brushed in order to obtain a roughness Ra of 1.5 m. This disk is preheated to a temperature of 150 C.

(77) The torch is used to apply a PEEK (polyether ether ketone) powder manufactured and marketed by VICTREX under the trade name VICOTE PEEK 709 in order to obtain a discontinuous deposit of 0.8 g and a roughness of 2.7 m.

(78) This disk prepared as such is successively covered with a primary layer and a top layer with a PTFE base.

(79) After baking at 415 C., the disk prepared as such is stamped in order to produce a bowl with a bottom of diameter 26 cm, interiorly coated with PTFE (nonstick coating).

(80) This coating does not have any cracks, or losses of adhesion.

(81) After an aging of 3 3-hour cycles in contact with boiling water, the adherence measured using a surface grid is equal to 100%.

(82) This type of bowl is also tested for its resistance in the dishwasher, after 20 washing cycles, the coating does not have any cracks or blisters.

(83) An abrasion test is also carried out via back and forth passages with an abrasive pad. After 15,000 passages, the coating does not have any scratches in the metal and its anti-adherence measured by the cleaning of the carbonized milk is 50.