Culinary item comprising a fluorocarbon resin and rare earth oxide coating and method for manufacturing said item

Abstract

Provided is a cooking item, at least one of the surfaces of which has a fluorocarbon coating including rare earth oxide fillers. The use of a composition including a fluorocarbon resin and rare earth oxide fillers makes it possible to obtain coatings, the mechanical properties of which (particularly in terms of hardness and resistance to abrasion) are reinforced without any breakdown in the non-stick properties of said composition. Also provided is a method for manufacturing such a cooking item.

Claims

1. A culinary item comprising a support having an inner surface capable of receiving foods and an outer surface intended to face a heat source, and a coating applied to at least one of the two surfaces, said culinary item being characterized in that the coating comprises at least one layer comprising: a matrix of fluorocarbon resin, alone or in a mixture with a binding resin that is thermostable and resistant to temperatures greater than 200 C., this resin or resins forming a continuous sintered network, and rare earth oxide layers dispersed in said matrix, 50% of which having a largest characteristic dimension greater than or equal to 0.1 m.

2. The culinary item according to claim 1, in which the binder resin is selected from the polyamide-imides (PAI), polyetherimides (PEI), polyamides (PI), polyetherketones (PEK), polyetheretherketones (PEEK), polyethersulfones (PES), polyphenylene sulfides (PPS) and mixtures thereof.

3. The culinary item according to claim 1, wherein the rare earth oxide fillers are present at a concentration ranging from 0.1 to 20% by weight relative to the total dry weight of the layer.

4. The culinary item according to claim 1, wherein the dry thickness of said layer ranges from 1 m to 25 m.

5. The culinary item according to claim 1, wherein the fluorocarbon resin is selected from the group comprising polytetrafluoroethylene (PTFE), modified PTFE, tetrafluoroethylene and perfluoropropyl vinyl ether (PFA) copolymers, and tetrafluoroethylene and hexafluoropropylene (FEP) copolymers.

6. The culinary item according to claim 5, wherein the fluorocarbon resin is polytetrafluoroethylene (PTFE), or a mixture of PTFE and PFA (PTFE/PFA) or a mixture of PTFE and FEP (PTFE/FEP) or a mixture of PTFE, PFA and FEP (PTFE/PFA/FEP).

7. The culinary item according to claim 1, wherein the rare earth oxide fillers are lanthanide oxide fillers.

8. The culinary item according to claim 7, wherein the rare earth oxide fillers comprise cerium oxide, alone or in a mixture with at least one other lanthanide oxide.

9. The culinary item according to claim 1, wherein the largest characteristic dimension of 50% of the rare earth oxide fillers ranges from 0.1 m to 50 m.

10. The culinary item according to claim 9, wherein the largest characteristic dimension of 50% of the rare earth oxide fillers ranges from 1 m to 50 m, and preferably from 5 m to 25 m.

11. The culinary item according to claim 9, wherein the largest characteristic dimension of 50% of the rare earth oxide fillers ranges from 0.1 m to 1 m, and preferably from 0.1 m to 0.3 m.

12. The culinary item according to claim 1, wherein the support is made of a metal, glass, ceramic or terracotta material.

13. The culinary item according to claim 12, wherein the support is metal and is made of aluminum, anodized or not, and that may be polished, brushed, sanded, or bead-blasted, or of steel that may be polished, brushed, sanded or bead-blasted, or of stainless steel that may be polished, brushed, sanded, or bead-blasted or of cast steel, cast aluminum, or cast iron, or of copper, that may be hammered or polished.

14. The culinary item according to claim 13, wherein the support is made of metal and comprises alternate layers of metal and/or metal alloy, or a cap of cast aluminum, aluminum or aluminum alloy reinforced with a stainless steel exterior base.

15. A method of preparing the culinary item described according to claim 1, said method comprising the following steps: a.) providing a support; b.) preparing an aqueous dispersion of fluorocarbon resin, optionally mixed with a binder resin; c.) dispersing rare earth oxide fillers in the fluorocarbon resin dispersion; d.) applying the dispersion obtained in step c) onto at least one surface of the support; and e.) baking of the applied dispersion.

Description

DETAILED DESCRIPTION OF THE INVENTION

(1) In these examples, except as otherwise noted, all percentages and portions are expressed as percent by weight.

EXAMPLES

(2) Products aluminum support; aqueous dispersion of 60% PTFE; octyl phenol ethoxylate; aqueous dispersion of 25% carbon black; colloidal silica as an aqueous solution containing 30% silica sold by Clariant under the commercial name Klebosol; polyamide imide in aqueous solution; acrylic polymer emulsion with 5% of alumina fillers; water; treated mica flakes; alumina F400 (D50=17.3 microns)

(3) Tests

(4) Scratch Test

(5) The scratch resistance of the coating is evaluated by subjecting the finish layer to the action of a green SCOTCH BRITE (trademark) style abrasive pad. The scratch-resistance of the coating is evaluated qualitatively, after multiple passes of the abrasive pad under a weight of 21 N. The action of the abrasive pad is then interrupted when the operator detects scratching (corresponding to the appearance of the support metal or of a sub-layer underneath the finish layer), or after completing 36,000 cycles (one cycle corresponding to one back and forth movement). Every 1000 cycles, the used abrasive pad is replaced by a new abrasive pad.

(6) Test for Loss of Non-Stick Properties

(7) The non-stick properties of the finish coating are evaluated using the carbonized milk test according to standard NF D 21-511. The operator checks for the appearance of scratching and performs a burned milk adhesion test every time the abrasive pad is replaced (see results in Table 6).

EXAMPLES PRODUCED (EXPERIMENTAL CONDITIONS AND COMPOSITIONS)

(8) As regards Example 1 and Comparative Examples 1 and 2, a PTFE-based primer composition was prepared, the composition of which is described in Table 1 below.

(9) This composition forms, after being sprayed onto an aluminum support having previously been subject to surface treatment and blasting, a primer layer for a coating according to the invention, comprising rare earth oxides (for Example 1), or a conventional coating with alumina fillers, or having no fillers (Comparative Examples 1 and 2, respectively).

(10) After the primer layer is applied, it is dried at 70 C. for 4 minutes.

(11) TABLE-US-00001 TABLE 1 Components of the Quantities by primer composition weight (% wet weight) Aqueous dispersion of 60% PTFE 22.0 Octyl phenol ethoxylate; 0.3 Aqueous dispersion of 25% carbon 3.6 black; 30% colloidal silica 14.5 Polyamide imide in aqueous solution 38.4 5% acrylic polymer emulsion 4.2 Alumina fillers 1.5 Water 15.5 TOTAL 100.0

Example 1 According to the Invention

(12) A finish composition with cerium oxide fillers is prepared, the composition of which is indicated in Table 2 below.

(13) After the application of the primer layer onto the aluminum support (according to the conditions indicated above) and the cooling of the resulting primer layer, the finish composition with rare earth oxide fillers is applied, by spraying, onto the primer layer.

(14) Then, a step to dry the obtained finish layer with rare earth oxide fillers is performed at 70 C. for 1 minute and the entirety is then baked at 415 C. for 11 minutes.

(15) The thickness of the baked films is 10 microns for the primer layer and 18 microns for the finish layer with rare earth oxide fillers.

(16) TABLE-US-00002 TABLE 2 Quantities by Components of the finish composition weight (% wet weight) including rare earth oxide fillers (preferred example) Aqueous dispersion of 60% PTFE 84.0 Treated mica flakes 0.2 5% acrylic polymer emulsion 10.0 Cerium oxide 2.8 D50 = 17.6 microns) Water 3.0 TOTAL 100.0

Comparative Example 1

(17) A finish composition with alumina fillers is prepared, the composition of which is indicated in Table 3 below.

(18) After the application of the primer composition to the aluminum support (according to the conditions indicated above) and the cooling of the resulting primer layer, the finish composition with alumina fillers is applied, by spraying, onto the primer layer.

(19) Then a step to dry the finish layer with alumina fillers is performed at 70 C. for 1 minute and the entirety is then baked at 415 C. for 11 minutes.

(20) The thickness of the baked films is 10 microns for the primer layer and 18 microns for the finish layer with alumina fillers.

(21) TABLE-US-00003 TABLE 3 Quantities by Components of the finish composition weight (% wet weight) including alumina fillers (preferred example) Aqueous dispersion of 60% PTFE 84.0 Treated mica flakes 0.2 5% acrylic polymer emulsion 10.0 Alumina F400 (D50 = 17.3 microns) 2.8 Water 3.0 TOTAL 100.0

Comparative Example 2

(22) As regards comparative example 2, a finish composition without fillers was prepared, the composition of which is described in Table 4 below.

(23) After the application of the primer layer to the aluminum support, according to the conditions indicated above) and the cooling of the resulting primer layer, the finish composition without fillers is applied, by spraying, onto the primer layer.

(24) Then a step to dry the finish layer without fillers is performed at 70 C. for 1 minute, and the entirety is then baked at 415 C. for 11 minutes.

(25) The thickness of the baked films is then 10 microns for the primer layer and 18 microns for the finish layer without fillers.

(26) TABLE-US-00004 TABLE 4 Quantities by Components of the finish composition weight (% wet weight) without fillers (preferred example) Aqueous dispersion of 60% PTFE 86.8 Treated mica flakes 0.2 5% acrylic polymer emulsion 10.0 Water 3.0 TOTAL 100.0

(27) Results of Tests Conducted

(28) Scratch Test and Test for Loss of Non-Stick Properties for the Obtained Coatings

(29) The ability of coatings to withstand abrasion and loss of non-stick properties is assessed in Example 1 and in Comparative Examples 1 and 2 in accordance with the tests described above. The results obtained are presented in Table 5 below:

(30) TABLE-US-00005 TABLE 5 Appearance of Non-stick scratching properties after Examples after 36000 cycles 36000 cycles Example 1 No Excellent Comparative Example 1 No Adherence of milk Comparative Example 2 Yes Excellent at 26000 cycles

(31) This Table 5 demonstrates that the inclusion of cerium oxide fillers in the finish layer enhances the mechanical properties of the coating without diminishing its non-stick properties.