KR102174186B1 - Enamel coating comprising anisotropic particles and cooking item provided with such a coating - Google Patents

Abstract

The present invention comprises at least one layer 31 of enamel in which particles 4 having an anisotropic shape are dispersed, the layer comprising the layer 31 of enamel in which the anisotropic particles 4 are in the form of a film. It relates to a protective coating comprising at least one region 5 essentially comprising vertical particles 41. The invention also relates to articles comprising such coatings, such as cooking articles, and methods of applying such coatings to substrates.

Description

Enamel coating containing anisotropic particles and cooking utensils equipped with such coating {ENAMEL COATING COMPRISING ANISOTROPIC PARTICLES AND COOKING ITEM PROVIDED WITH SUCH A COATING}

The present invention relates generally to articles provided with an enamel coating comprising anisotropic particles (flakes or fibers) that can be used on any type of substrate, in particular a metal substrate.

The invention also relates to a method of applying such a coating to a support.

The target area is mainly heating applications.

For the purposes of the present invention, a “heating article” is an article that includes a self-heating system, an article that is heated by an external system and is capable of transferring the thermal energy generated by the system to a third substance or object in contact with the article It means an article designed to contain an article that is present, or another previously heated article.

Examples of heating articles usable in accordance with the present invention include, in particular, cooking articles (such as sauce pans, casseroles, woks, crepe pans, crock pots, cooking pots, casseroles, etc.), heating covers and heating blender bowls of food or beverage manufacturing equipment. Include. However, the present invention also provides for any other type of surface and article such as tableware such as trivets, iron soles, curling irons, straightening irons, radiators, towel rails, wood stoves, barbecue grills, barbecue boxes, barbecue tanks and flats. It could be about kiln articles.

The enamel coating is particularly well suited for the field of heating appliances, in particular cooking appliances, and irons, more specifically iron bases.

In the case of an iron base, the tribological, thermal and physiochemical properties of the coating form the basis to ensure easier ironing. Thus, the enamel coating is an ideal compromise for coating the metal frame of an iron base, as it retains heat well, has a low coefficient of friction that does not change significantly with temperature, is hydrophilic and hydrolysis resistant. The disadvantage of enamel coatings for applications such as irons (including steam irons, dry irons and steam generators in particular) is their low impact resistance. In fact, small pieces of enamel may appear on the coated edge of the enamel cap (more specifically on the perimeter of the coated cap), especially if the coating is impacted during use. Small pieces of enamel can also appear through repeated contact with metal components (button holes, snaps, zippers, etc.) placed on the textile to be ironed.

Enamel coatings are also suitable for the field of culinary products, as they make it possible to obtain a colored coating with a basic decorative appearance that is not only dishwasher resistant and highly resistant to flames and scratches, but often a deciding factor in consumer choice. Especially very suitable. However, they have the disadvantage that the cookware is easily peeled off in certain particularly sensitive areas where it undergoes maximum wear and tear. These areas are generally located on the curve of the article or on the connection close to the handle.

Sensitive areas for cooking utensils are, in particular, areas where the bottom and side walls of the appliance meet, the top edge of the appliance that has been rounded (deformed) to create a smooth, flat edge, the area that supports the connection of the handle (this area is a fixed part) Because it can be deformed due to the welding of), and a floor that comes into contact with the burner.

Additionally, the enamel coating also undergoes varying degrees of thermal expansion depending on the location of the flame under the article. However, it is important that the coating has uniform thermal expansion, otherwise micro-cracking will occur and resistance to dishwashing is reduced.

In order to avoid the problems mentioned above, the applicant has developed an enamel coating containing flakes, generally anisotropic particles, oriented essentially perpendicular to the coating formed in the sensitive area.

For the purposes of the present invention, "particles oriented essentially perpendicular to the coating" means that the majority of the particles are 20° to 90°, preferably 45° to 90°, optimally 60° relative to the average coating plane. It means particles inclined at an angle α of to 90°.

Incorporation of particles, such as flakes, into enamel-type coatings is known to the skilled person. Thus, for example, French patents FR2472596 and FR813737 describe enamel coatings for cookware in which mica or nacre flakes are incorporated into the enamel coating.

In addition, international application WO 2011/42886 and U.S. Patent 3,480,461 relate to decorating an iron base using an enamel coating comprising a pigment or filler.

However, none of these references describe any arbitrary particle orientations (flakes, pigments or fillers) in a particular area of the coating, especially for the purpose of reinforcing the area, and furthermore, the orientation is It is also not specified that this is achieved using a magnetic field of.

More specifically, the present invention includes a support having two opposite surfaces, at least one of the opposite surfaces is covered by a protective coating, and the protective coating includes at least one enamel layer in which anisotropic particles are dispersed, The enamel layer relates to a heating article, characterized in that the anisotropic particles comprise at least one region essentially perpendicular to the enamel layer in the form of a film.

The anisotropic particles may advantageously represent from 0.05 to 10% by weight, preferably from 0.1 to 7% by weight and optimally from 1 to 5% by weight of the total weight of the enamel layer. Ideally, the anisotropic particles represent 2-3% by weight of the total weight of the enamel layer.

In the area where the particles are essentially vertical, the resistance to scaling and impact is significantly improved. Also, the thermal expansion of the region is not different from that of the rest of the coating.

For the purposes of the present invention, "anisotropic particles" mean particles whose dimensional properties are not identical in all directions, for example fibers (essentially one-dimensional shape) or flakes (essentially two-dimensional or flat shape).

For the purposes of the present invention, "particles essentially perpendicular to the film" means particles, most of which are inclined at an angle of 20° to 90° with respect to the average plane of the film.

Depending on the type of anisotropic particles used, this orientation of the anisotropic particles can be obtained in various ways.

Thus, in the case of particles (such as fibers) that can be oriented by mechanical means, the orientation essentially perpendicular to the coating layer is, for example, the coating application method (orientation using a one-way applicator such as a micro-nozzle) It may be due to positioning due to

In the case of particles that can be oriented by physical means (e.g., electric or magnetic), the essentially perpendicular orientation of the anisotropic particles relative to the coating layer is, for example, the magnetizable particles under the effect of a magnetic field or the effect of an electric field. It may be due to positioning subsequent to or concurrent with the application of the coating, such as orienting the convertible particles under.

For the purposes of the present invention, "magnetic particle" means a particle that can be oriented under the effect of a magnetic field.

Various types of magnetizable particles can be used.

In the present invention, the magnetizable particles may advantageously be particles comprising at least one ferromagnetic metal.

They may be homogeneous, ie consist of the same material or composite, ie the magnetizable particles have a core-shell structure in which the ferromagnetic metal is within the core and/or shell of the particle.

One specific example of a composite magnetizable particle is a mica flake coated with a ferromagnetic material, for example a mica flake coated with ferrite in the form (MO, Fe ₂ O ₃ ) (where M is a divalent metal), e.g. For example, it will be Fe ₃ O ₄ (magnetite) or mica flakes coated with Fe ₂ O ₃ or FeO. Other materials with ferromagnetic properties: For example, Heusler alloys (61% Cu, 24% Mn and 15% Al) consisting only of cobalt, nickel, or non-ferromagnetic metals, or certain rare earths such as lanthanide, or Copper-manganese and aluminum oxide can also be used.

The advantage of coated mica flakes is that they are particularly resistant to high firing temperatures of enamels for metals, ie from 550° C. for enamels on aluminum to 850° C. for enamels on steel or cast steel. In addition, these mica flakes are more resistant to the alkalinity of the enamel slip generated by hydrolysis (eg, in the case of aluminum, the enamel slip has a pH of 13). It may also refer to stainless steel fibers coated with a sol-gel material to provide corrosion protection during various stages of coating application, or flakes in which the core is made of a ferromagnetic metal and the shell is made of a sol-gel material.

The coating according to the invention may also advantageously contain non-magnetizable particles to improve the coating strength.

For the purposes of the present invention, “non-magnetizable particles” means non-magnetizable or slightly magnetizable particles with zero or low magnetic moment (less than 1 uem/g).

These non-magnetizable particles can have any shape (spherical, fibrous, flake or “irregular”) and can be micrometers or even nanometers in size.

Non-magnetic particles that can be used in the present invention are in particular mica flakes, or mica or silica flakes coated with titanium dioxide.

The protective coating of the present invention is also advantageously at least one in which the particles are essentially parallel and/or random to the enamel film layer, adjacent to the area where the particles are essentially perpendicular to the enamel coating layer, to reinforce the sensitive area. It may include an area of.

For the purposes of the present invention, "particles essentially parallel to the enamel coating layer" means particles, most of which are inclined at an angle of 0° to 20° to the coating layer.

Alternating regions in which the particles are essentially parallel and/or random with respect to the enamel layer, and the regions in which the particles are essentially perpendicular to the enamel layer can create a pattern that the user can perceive as a three-dimensional pattern element.

According to a first particularly advantageous embodiment of the invention, the enamel layer of the protective coating according to the invention may comprise a single continuous layer designed to be applied to a support.

According to a second particularly advantageous embodiment of the invention, the enamel layer of the protective coating according to the invention is

-A transparent sublayer that is continuous and does not contain magnetizable particles, designed to be applied to the support, and

-A continuous, partially or completely covering the lower layer, a finishing layer in which magnetizable particles are dispersed

It may include.

For the purposes of the present invention, "finish layer" means a layer designed to contact the environment.

According to a third particularly advantageous embodiment of the invention, the enamel layer of the protective coating according to the invention is

-A colored sub-layer that is continuous and designed to be applied to the support and does not contain magnetizable particles, and

-A continuous, partially or completely covering the lower layer, a finishing layer in which magnetizable particles are dispersed

It may include.

According to a particularly advantageous fourth embodiment of the invention, the enamel layer of the protective coating according to the invention is

-A transparent or colored sublayer that is continuous and does not contain magnetizable particles, designed to be applied to the support,

-A first finishing layer in which magnetizable particles are dispersed, which is continuous and completely covering the lower layer, and

-A second finishing layer which is continuous and partially or completely covering the first finishing layer, and also dispersed in magnetizable particles

It may include.

According to a fifth particularly advantageous embodiment of the invention, the enamel layer of the protective coating according to the invention is

-A colored sublayer in which magnetizable particles are dispersed, designed to be continuous and applied to the support, and

-A transparent finish layer that is continuous and partially or completely covering the sub-layer, in which magnetizable particles are also dispersed

It may include.

One such embodiment has the advantage of mechanically strengthening each layer and the mechanical bond between each layer.

Advantageously, for embodiments having at least two layers (embodiments 2 to 5), the lower layer may have a thickness of 5 to 30 μm, and the finish layer(s) have a thickness of 20 to 60 μm. Can have.

According to a particularly advantageous sixth embodiment of the invention, the protective coating according to the invention is

연속적이고 지지체에 도포되도록 설계된, 자화성 입자를 함유하지 않는 투명 또는 착색 하위층, 및-

A transparent or colored sublayer that is continuous and designed to be applied to the support and does not contain magnetizable particles, and

착색 층 또는 자화성 입자가 분산된 자화성 층이며, 연속적이고 상기 하위층을 부분적으로 또는 완전히 덮는 적어도 하나의 중간층

At least one intermediate layer which is a colored layer or a magnetizable layer in which magnetizable particles are dispersed, and which is continuous and partially or completely covers the lower layer

An enamel layer comprising a, and

-A first layer of a continuous magnetizable brightener in which magnetizable particles are dispersed, partially or completely covering the intermediate enamel layer, and

-A second layer of non-colored, transparent non-magnetic continuous polish that completely covers the first layer of magnetizable polish to ensure chemical resistance and resistance to dishwashing.

It may include.

Advantageously, in this sixth embodiment, the lower layer may have a thickness of 5 to 30 μm, and the middle enamel layer may have a thickness of 20 to 60 μm. With regard to the brightener layer covering the intermediate enamel layer, the magnetizable brightener layer may advantageously have a thickness of 15 to 40 μm, and the protective varnish layer may have a thickness of 10 to 20 μm.

In all these embodiments, for the purposes of the present invention, the "coloring layer" (whether underlayer, finish or varnish layer) is a thermostable pigment, such as spinel, ceramic pigment, oxide, organometallic such as ultramarine, (Non-magnetic) It means a layer containing at least one opaque pigment selected from mica or silica flake pigments, metal salts, thermochromic semiconductor pigments, or combinations thereof.

Advantageously, regardless of the embodiment, the enamel layer of the protective coating of the heating article according to the present invention may also comprise a discontinuous outer enamel layer added by silk screening or pad printing.

If the heating article according to the invention is a cooking article, the outer enamel layer may also comprise a circular filler, which is advantageously spherical with a diameter of 5 to 40 μm, preferably 15 to 20 μm, and The thickness varies from 10 to 30 μm. These beads protrude from the surface of the outer enamel layer.

Circular fillers (or beads) suitable for use in the outer enamel layer according to the invention include in particular stainless steel, copper, bronze or refractory steel beads.

Preferably, stainless steel beads are used. The circular filler is advantageously present in the outer enamel layer in 1 to 5% by weight of the total weight of the outer layer. These round fillers increase the resistance to abrasion and tear of the enamel coating, and also (when the filler is flush with the surface of the enamel layer) there is less contact surface between the article and the cooking surface and the lower the bead compared to the enamel layer. Reduces the coefficient of friction due to hardness. Thus, the coating can be easily cleaned and may not have the risk of scratching sensitive surfaces such as ceramic glass or induction cooktops.

The support of the article can be made of metal, glass or ceramic.

The metallic support according to the present invention

-Polished, brushed, micro-beaded, sanded, chemically treated aluminum or aluminum alloy, or cast aluminum, or a single layer made of polished, brushed, micro-beaded stainless steel or cast steel or aluminum Type structure, or

-In whole or in part, from outside to inside, ferritic stainless steel/aluminum/austenitic stainless steel, or stainless steel/aluminum/copper/aluminum/austenite stainless steel, or cast aluminum, aluminum lined underneath the outer stainless steel Or a multi-layered metal structure including a layer of an aluminum alloy cap

It is a support having.

Examples of articles according to the invention are, in particular, cooking utensils, heating covers, or heating blender bowls of food or beverage manufacturing equipment, iron soles, tableware such as trivets, radiators or wood stoves, curling irons and straightening irons, Includes towel rails or barbecue grills, boxes or tanks.

Finally, it is also an object of the present invention to apply a method for producing a coating comprising at least one enamel layer in which anisotropic particles are dispersed, on a heating article support, wherein the anisotropic particles are added to at least one of the enamel layers. Orienting on the area using physical means (e.g., using an electric or magnetic field) or mechanical means (e.g., if the coating is applied using a one-way applicator, such as a micro-nozzle). It features.

Support and anisotropic particles are those defined above.

Advantageously, the method according to the invention

a) providing a support;

b) applying at least one enamel composition in which anisotropic particles including magnetizable particles are dispersed, by pulverizing, on one of the support surfaces;

c) applying a magnetic field to orient the magnetizable particles by magnetization, wherein the magnetizing step c) is achieved during step b) of applying the enamel composition to the support, or immediately after the applying step b); next

d) optionally, preferably drying at a temperature between ambient temperature and 150° C.; next

e) firing at a temperature of at least 500°C.

It may include.

Magnetizable particles are those defined above.

In this embodiment of the method according to the invention, anisotropic magnetizable particles are used; Accordingly, the orientation step c) of the magnetizable particles is a magnetization step carried out by applying a magnetic field, which is carried out when the enamel composition is applied or after this application step b), but in any case before the firing step e).

After drying and firing, a protective coating is obtained that simultaneously has high resistance to scaling and impact and homogeneous thermal expansion throughout the coating.

In this embodiment of the method according to the invention in which the anisotropic particles are magnetizable and oriented by magnetization, the step b) of applying the enamel layer is advantageously

-b1) on one of the support faces, a sub-step of forming an unfired sub-layer by pulverizing a transparent or colored sub-layer enamel composition containing no magnetizable particles; next

-b2) on the unfired sub-layer, a sub-step of forming an unfired enamel finish layer by pulverizing at least one enamel finish composition in which magnetizable particles are dispersed

It may include.

Preferably, the step b) of applying the enamel layer is also performed after step b2), but before the firing step e), on the unfired enamel finish layer, of at least one second enamel finish composition in which magnetizable particles are also dispersed. It may include a step b3) of forming a second unbaked enamel finish layer by pulverization.

Finally, the method according to the invention also comprises or does not comprise circular fillers, after step d) of drying the finished enamel layer(s) formed (therefore, the drying step is no longer optional and essential in this embodiment). It may include a step of silk-screening a layer of enamel paste that may not be applied onto the enamel finish layer.

These round fillers (or beads) are those defined above.

Other benefits and specificities of the invention can be seen in the following description provided as a non-limiting example and reference may be made to the accompanying drawings:

1 shows a schematic cross-sectional view of a part of a support of an article according to the invention according to a first embodiment;

2 shows a schematic cross-sectional view of a part of a support of an article according to the invention according to a second embodiment (which shows two sub-embodiments 2a and 2b);

3 shows a schematic cross-sectional view of a part of a support of an article according to the invention according to a third embodiment (which shows two sub-embodiments 3a and 3b);

4 shows a schematic cross-sectional view of a part of a support of an article according to the invention according to a fourth embodiment;

5 shows a schematic cross-sectional view of a part of a support of an article according to the invention according to a fifth embodiment (which shows four sub-embodiments 5a to 5d);

6 shows a schematic cross-sectional view of a part of a support of a cooking appliance according to the invention according to a sixth embodiment;

Fig. 7 shows a schematic cross-sectional view of a part of an iron sole according to the invention according to a seventh embodiment;

-Fig. 8 shows a bottom view of the bottom plate of the iron shown in Fig. 7;

9 shows a schematic cross-sectional view of the placement of a magnet under the support of a coated article for carrying out the magnetization step;

Fig. 10 is a detailed view of Fig. 9 showing area Z (defined by the edges and gaps of two magnets);

-Fig. 11 is a top view (photo) of a part of the base of the iron on which the permanent magnet is located in the form of a triangular band;

Fig. 12 is a detailed view of Fig. 1 showing a specific area Z (defined by the edges and gaps of two magnets);

13 shows a series of three images from a scanning electron microscope (SEM), 13a to 13c, of a cross section of the iron base of FIG. 3 showing a specific area Z.

1 shows a part of a support of an article according to a first embodiment. One 21 of the surfaces of the support 2 is provided with a continuous single-layered film 31 of enamel coating in which anisotropic particles 4 and 41 are dispersed.

FIG. 1 shows that the film 31 comprises at least one area 5 in which the anisotropic particles 41 are essentially perpendicular to the film 31.

This particular orientation of the anisotropic particles 41 in the region 5 can be achieved, for example, by magnetization when the anisotropic particles 4 and 41 contain magnetizable particles. In practice, it proceeds as follows: adjacent to the uncoated side 22 under the support 2, there is a permanent magnet, in particular an elastomeric magnet (which limits the magnetization conditions to temperatures below 80°C) or an electromagnet. It is also possible to use ferrite or neodymium permanent magnets or electro-inducing magnets. In this case, then the maximum temperature of the magnetization condition may exceed 80°C, but it must be kept below the Curie point of the magnet used. In order to obtain a specific holographic image, magnets having the desired shape are used, which are cut and/or machined using permanent and electro-inducing ferromagnetic materials.

Preferably, a magnet with a magnetic field having a strength of 40 to 100 mT, preferably approximately 70 mT is used.

1 shows that the magnetizable particles 41 of a single-layered enamel film 31 are perpendicular to the film in the area 5 along a field line created by a permanent magnet located just below a specific area 5. Clearly indicates that it is oriented

2 shows a schematic cross-sectional view of a part of a support 2 of an article according to the invention in accordance with the second embodiment, which represents the two sub-embodiments shown in FIGS. 2a and 2b, respectively. The two sub-embodiments shown in FIGS. 2A and 2B differ from the embodiment shown in FIG. 1 in that the enamel coating 31 in film form is a double layer.

In the two sub-embodiments shown in Figures 2a and 2b, the bilayer coating 31 is one sublayer 310 layered on one of the sides 21 of the support 2 (containing no anisotropic particles ) And one finishing layer 311 in the form of a continuous enamel film covering the lower layer 310, wherein the anisotropic particles 4 and 41 are included in the finishing layer 311. The lower layer 310 may be colored as shown in FIG. 2A or may be transparent as shown in FIG. 2B. The orientation of the anisotropic particles 41 can be achieved by magnetization of the anisotropic particles 41 in the case of containing magnetic particles, in the same manner as in the first embodiment.

3 shows a schematic cross-sectional view of a portion of a support of an article according to the invention according to a third embodiment, which also has two sub-embodiments shown in FIGS. 3A and 3B, respectively. Each of these sub-embodiments 3a and 3b is shown in FIGS. 2a and 2b, respectively, in that the enamel coating 31 further comprises a second finishing layer 312 in which the anisotropic particles 4, 41 are also dispersed. It is different from the embodiment.

FIG. 3 also shows a region 6 in which the double-layered enamel coating 31 of FIG. 3 has anisotropic particles 4 that are essentially parallel to the coating 31 and anisotropic particles 41 that are essentially perpendicular to the film. It represents having a three-dimensional pattern created by alternating the regions 5 having.

Here also, the specific orientation of the anisotropic particles 41 in the region 5 will be achieved by magnetization if the anisotropic particles are magnetizable.

Thus, in the case of a cookware in which the bottom of the support designed to be coated is generally circular in shape, this magnetization is, for example, on the side of the uncoated side 22 under the support (usually circular) For example, this can be achieved by placing a plurality of concentric elastomeric permanent magnets that independently emit magnetic fields of constant or variable strength of approximately 80 mT. Such concentric magnets can advantageously be formed as a central disk having a small diameter (eg 15 mm or less) and a plurality of concentric rings positioned around said central disk having a width of approximately 10 to 15 mm. Such magnets can advantageously be placed on a substrate (eg, a stainless steel plate) that can move vertically relative to the article support. This movement can be accomplished using a jack that moves the substrate (or plate) so that a gap is created in the vicinity of the article to be magnetized.

In the case of an iron sole with a generally triangular cap designed to be coated, for example, a band magnet (for example made of elastomer) is the side of the uncoated side 22 below the area to be strengthened of the support 2 Exists in the phase. These bands may be continuous or discontinuous, and may have a generally triangular cap. It emits an independently measured magnetic field of constant or variable intensity, eg approximately 80 mT.

Then, the magnetizable anisotropic particles are perpendicular to the support 2 (or film 31) along the inverse line, i.e. in the region 5 with the magnet below it (the inverse line is perpendicular to the enamel coating 31). And in a region 6 in which the inverse line is parallel to the support 2 to the support 2 (and thus to the coating 31) parallel to the gradual orientation continuum of magnetizable anisotropic particles between these two regions. Oriented.

4 shows a schematic cross-sectional view of a part of a support of an article according to the invention according to a fourth embodiment, wherein the fourth embodiment is in that the sublayer 310 contains anisotropic particles (4, 41). It differs from the sub-embodiment shown in FIG. 2A. As in the third embodiment shown in FIGS. 3A and 3B, the double layered enamel coating 31 of FIG. 3 has a film and a region 6 having anisotropic particles 4 essentially parallel to the coating 31. It contains a three-dimensional pattern formed by alternating regions 5 with anisotropic particles 41 which are essentially perpendicular to. If the anisotropic particles 41 contain magnetic particles or are magnetic particles, the particle orientation in the region 5 can be achieved by including a magnet under the support 2.

5 shows a schematic cross-sectional view of a portion of a support of an article in accordance with the present invention according to a fifth embodiment, said fifth embodiment representing four sub-embodiments in FIGS. 5A-5D, respectively. These drawings are

-Transparent (as shown in FIGS. 5A and 5B) or colored (as shown in FIGS. 5C and 5D) sublayer 310 that does not contain magnetizable particles 4, 41

-A colored layer (as shown in Figs. 5b and 5d) or an anisotropic particle (4, 41), preferably a magnetizable layer in which magnetizable particles are dispersed (as shown in Figs. 5a and 5c), continuous And the intermediate layer 313 covering the lower layer 310

It shows a support 2 having one of the sides 21 coated with an enamel layer 31 comprising.

The middle layer 313 is

-A first layer 321 of a transparent or colored continuous brightener in which anisotropic particles (4, 41), preferably magnetizable particles are dispersed, and

-A second layer 322 of non-colored continuous polish that completely and/or partially covers the first layer 321 of the polish

Covered by itself.

Here also, the specific orientation of the anisotropic particles 41 in the region 5 can be achieved by magnetization if the anisotropic particles are magnetizable.

6 shows a schematic cross-sectional view of a portion of a support of a cooking appliance according to the invention according to a sixth embodiment. In this embodiment specific to a cooking article, such as a pan 1, the support 2 is designed to be located on an inner side 22 that faces the food that may be located within the pan 1 and an outer heat source. Includes cotton (21). The support 2 is on its inner surface 22 an anti-stick coating 7 (for example, a sol-gel or fluorocarbonate resin) and on its outer surface 21

-Continuously colored enamel layer (31) containing magnetizable particles (4, 41)

-A continuous non-colored brightener layer in which magnetizable particles (4, 41) are dispersed,

-A non-continuous outer enamel layer 33 produced by silk screening or pad printing, containing metal beads 34 (copper, bronze or fire resistant steel)

It includes a coating (3) comprising a.

Fig. 7 shows a schematic cross-sectional view of a part of an iron sole plate according to the present invention according to the seventh embodiment, and Fig. 8 shows a bottom view of the iron sole plate shown in Fig. 7.

In this specific embodiment of the iron soleplate, the support 2 has essentially the same coating 3 as shown in FIG. 6 on its outer surface 21 designed to contact the garment to be ironed: the only difference is discontinuous It is the absence of circular fillers in the outer enamel layer 33.

Figures 9 to 13 are shown in more detail in the following examples illustrating the invention without limiting its scope.

In these examples, unless stated otherwise, all percentages and parts are expressed as mass percentages.

Example

Test of resistance to scaling

The ability of various protective coatings of similar thickness (70-80 μm) applied to the same metallic substrate to resist scaling was evaluated as follows.

These coatings were applied to 10 mm long scratches created by diamond points calibrated to 50 μm in diameter by applying a force gradually increasing from 0 to 5 Newtons. To do so, the inventors used an apparatus commercially available from CSM Instruments under the name "Microscratch Tester".

After the scratch was formed, the minimum force required for the coating to scale until the metal was visible was determined under the microscope (see results in Table 9).

product

Support

-A cookware support made of an aluminum alloy (eg alloy 4917)

-Iron base cap made of aluminum alloy (eg alloy 3003)

-Cooking utensil support, either cast steel or sheet steel

Ferromagnetic flakes

In the present invention, ferromagnetic flakes usable in the B1 and V1 compositions include:

-Iron oxide coated mica flakes (magnetizable flakes) marketed under the name STAPA TA Ferricon 200 by Eckart,

-Iron oxide-coated mica flakes (magnetizable flakes) marketed under the designation Blue or Green Colorona Blackstar by Merck,

-Uncoated mica flakes (non-magnetizable flakes) marketed by Merck under the name Iriodin 119.

Filler

-Stainless steel beads.

Composition

Colored enamel slip composition B1 containing magnetizable fillers for aluminum substrates (cookware, iron bases, etc., which are aluminum or cast aluminum)

Enamel frit slip B1 of the composition provided in Table 1 was prepared.

<Table 1>

The values shown are parts by weight based on 100 parts by weight of frit (a standard amount of the slip composition).

The composition of the enamel frit F1 is provided in Table 2 below.

<Table 2>

The value shown is the mass percentage to the frit mass.

Enamel Slip Composition B2 for Support of Cast Steel Cookware

Enamel frit slip B2 of the composition provided in Table 3 was prepared.

<Table 3>

The values shown are parts by weight based on 100 parts by weight of frit (a standard amount of the slip composition).

The composition of the enamel frit F2 is provided in Table 4 below.

<Table 4>

The value shown is the mass percentage to the frit mass.

Colored brightener composition V1 containing magnetizable filler

To prepare a brightener composition V1 of the composition provided in Table 5 below.

<Table 5>

White Cover Enamel Slip Composition B3 for Cast Steel (Contains Magnetophilic Filler)

A colored enamel frit slip B3 designed to produce a white cover enamel was prepared. Its composition is provided in Table 6 below.

<Table 6>

Table 7 shows the composition of frit F3 used in the white cover enamel.

<Table 7>

Silk screening paste composition (with and without circular fillers)

A first silk screening paste composition P3 of the composition given in Table 8 below was prepared containing a filler.

A second silk screening paste composition P4 of the composition also given in Table 8 below was prepared without containing a filler.

<Table 8>

Example 1: Preparation of a protective coating according to the invention on the outer surface of an aluminum alloy cookware support.

Using fine pulverization, Slip B1 of the composition provided in Table 1 was applied to the outer surface of an aluminum alloy cooking utensil support to produce an enamel layer 31 (approximately 35 μm thick). Then, varnish V1 of the composition provided in Table 5 was applied to the enamel layer 31 to produce a varnish layer 32 (approximately 35 μm thick).

The magnetizable flakes contained in the enamel layer 31 and the varnish layer 32 are, as shown in Figs. 9 and 10, under the substrate (in this case, under the side of the support opposite the coated side). Using a 70 mT magnetic field using permanent magnets 51 and 52, immediately after being applied to these layers, they were oriented using magnetization in certain areas of the protective coating. Under the influence of the magnetic field, the mica flakes were oriented essentially vertically along the inverse line, ie perpendicular to the magnet, especially in the regions P1 and P2 shown in FIG. 9, due to their magnetic iron oxide coating.

In order to promote this flake orientation, it was desirable that the viscosity of the applied layer was as low as possible. To this end, a small amount of heavy non-COV solvent, such as hexylene glycol, was added to reduce evaporation during pulverization and to increase the duration of application of the magnet to facilitate orientation after pulverization. Thus, it was possible to eliminate any drying step of the enamel layer prior to orientation of the magnetic filler. However, it was possible to apply magnets until the final drying of the coating to enhance orientation. This mode was particularly recommended when a design with a clear relief effect is desired.

Subsequently, these layers were dried at a temperature of less than 150°C, preferably 60 to 80°C to achieve a dry biscuit, on which the enamel paste P3 (containing steel beads) of the composition provided in Table 8 was silk-screened to obtain a discontinuous outer enamel. Layer 33 was created. The article was then fired for 5 to 30 minutes at 500 to 1000° C. in a standard convection or spinning oven depending on the support to be coated.

This coating was observed under a scanning electron microscope (SEM) in area (Z) to produce the SEM image shown in FIG. 13 (for the iron base), which showed the following:

-The flakes tend to be oriented perpendicular to the support in a position where the line of force is perpendicular to the support 2, i.e. in the region C corresponding to the region 5 (i.e. most of them are of 45 to 90° Exists at an angle of inclination to the support) and (Fig. 13c)

-The flakes tend to be oriented parallel to the support, in a position where the inverse line is perpendicular to the support 2 (i.e., most of them are present at an angle of inclination to the support less than 20°) (Fig. 13b, in particular The area (B) corresponding to the area (6) is indicated).

Example 2: Preparation of a protective coating according to the invention on the cap of an iron base.

The same coating as in Example 1, which did not contain steel beads in the outer enamel layer (because this outer enamel layer was created using silk screening paste P4 not containing steel beads), was applied to the cap of the iron base.

The magnetizable particles are two permanent magnets 51 and 52 located under the substrate (in this case, under the side of the support opposite to the coated side), as shown in Figs. 9 and 10 and as actually shown in Fig. 11. ) Was oriented as in Example 1 under a 70 mT magnetic field. Under the influence of the magnetic field, the mica flakes were oriented along the inverse line, that is, perpendicular to the magnet, which is essentially perpendicular, since they are coated with magnetic iron oxide (region (C)).

A scanning electron microscope (SEM) image of the region Z of this coating is shown in Fig. 13 (Figs. 13A to 13C show regions (A) to (C), respectively).

An optical microscope image of the region Z of this coating is shown in Fig. 12, where various regions A, B and C can be viewed sequentially. In this drawing,

-The region (C) (corresponding to reference number 5 in Figs. 1 to 7), which is the area between the two magnets 51 and 52, in which the magnetic field line is perpendicular to the support, is, if not impossible, the reflection of magnetizable particles. Because it is very difficult to see (due to their vertical position relative to the support), it is a black area,

-The area (B) located at the edge of the magnet 51 (corresponding to the reference number 6 in Figs. 1 to 7), in which the inverse line is parallel to the support, is the area in which the reflection of the magnetizable particles is the strongest, so that Area;

-The area (A), which is essentially defined as the central part of the magnet 51, has an average brightness, since the magnetizable particles are oriented at an intermediate angle with respect to the support (above 20° but below that shown in area C). (Between what was observed in area (B) and what was observed in area (C)).

Example 3: Preparation of a protective coating according to the invention on the inner and/or outer surfaces of a cast steel cookware support.

This article will generally be made in two layers in two firing sessions.

A first layer of generally opaque enamel slip B2 (see Tables 3 and 4) was applied using pulverization to the inner and outer walls of a cookware support made of cast steel that was first blasted and cleaned. This layer will be fired at 800° C. to 850° C. for 4 to 12 minutes.

It is possible to use ferromagnetic flakes for the first layer: when using them, their orientation will be facilitated when the enamel is still liquid, i.e. applying magnets before drying and firing. Drying will ensure that the orientation of the flakes applied to the magnetic field of the magnet is maintained.

After firing and cooling the enamel article having the first layer, a cover enamel slip B3 was applied.

This second layer will be 100 to 200 μm thick. This layer will increase the mechanical strength for flake orientation when a magnetic field is applied. This step will be enhanced and facilitated when the enamel slip is still liquid (enhanced mobility). This second firing should be between 750° C. and 820° C. for 4 to 12 minutes.

In the case of cast steel metal for culinary applications or small appliance applications, the enamels described above may be applied to the interior of the article or to the exterior of the article. Their mechanical properties can be enhanced on the inside of the article (to withstand multiple contacts with a foamer, knife, spatula, etc.) or on the outside of the article (to withstand contact with a cooktop, sink, oven rack, etc.).

The coating described above provided a significant improvement compared to the same coating that did not contain oriented magnetizable flakes within slip B3. Optimized resistance to scaling was beneficial, for example, in the case of impacting metallic instruments during regular use.

The increase in resistance could be measured using a non-standardized test using a 300 g hammer that descends to the surface of the cast enamel article in less than 1 second from a height of 15 cm. When using flakes for the slip, the impact did not cause scaling, and scaling was present without the flakes.

Comparative Example 4: Preparation of a protective coating containing no magnetizable particles applied to the outer surface of an iron base.

Similar to Example 2, a protective coating comprising an enamel layer 31 was created, over which a varnish layer 32 followed by a silk-screen enamel layer 33 was added. The protective coating in Comparative Example 4 was different from the protective coating of Example 1 in that it lacked magnetizable flakes in the enamel layer 31, the varnish layer 32 and the silk-screen enamel layer 33.

Example 5: Evaluation of scaling resistance for aluminum cooking utensils

The ability of the protective coating to resist scaling in regions (B and C) in Examples 1 and 2, as well as in Comparative Example 4 (no specific region since there is no magnetization) was evaluated according to the test described above. The results are shown in Table 9 below.

<Table 9>

The delamination values shown in Table 9 correspond to the average metal fragment values of 4 measurements per sample.

The comparison of the delamination value measured in the region (B) in Examples 1 or 2 and the value from Comparative Example 4 is that the horizontal flake can facilitate delamination, so that the magnetizable flake does not exist. When the more particles are oriented parallel to the coating, it indicates that the force required to obtain the delamination reaching the metal during the test is lower.

The comparison of the delamination value measured in the region (C) of Example 1 or 2 and the value measured in the region (B) of the same example is, when the particles are oriented perpendicular to the coating than when the particles are parallel, It clearly indicates that the force required to obtain the delamination reaching the metal during the test is high, which means that the scaling resistance is higher if the coating contains oriented particles. In this case, they serve to strengthen.

Claims (30)

Comprising a support (2) having two opposing faces (21, 22), at least one of said opposing faces (21) being covered by a protective coating (3),
The protective coating (3) includes at least one enamel layer (31) in which anisotropic particles (4, 41) are dispersed, and the enamel layer includes an enamel layer (31) in which the anisotropic particles (4, 41) are in the form of a film. Heating article (1), characterized in that it comprises at least one region (5) comprising particles (41) perpendicular to ). The article according to claim 1, wherein the particles (4, 41) represent 0.05 to 10% by weight of the total weight of the enamel layer (31). The article according to claim 1 or 2, wherein the particles (4, 41) comprise particles (41) which can be oriented by mechanical or physical means. 4. The article of claim 3, wherein the oriented particles (41) are magnetizable particles. 5. The article of claim 4, wherein the magnetizable particles (41) comprise at least one ferromagnetic metal. 5. The article of claim 4, wherein the enamel layer (31) further comprises non-magnetic particles. 5. The article of claim 4, wherein the magnetizable particles (41) and the non-magnetic particles have a core-shell structure. 8. An article according to claim 7, wherein the ferromagnetic metal of the magnetizable particles (41) is within the core and/or the shell of the particles (41). At least one according to claim 1 or 2, wherein adjacent to the region (5), the anisotropic particles (4) are located randomly or so as to be inclined at an angle of 0° to 20° relative to the enamel layer (31). The article further comprises an area (6) of. 10. The article according to claim 9, wherein the alternating regions (5 and 6) create a pattern. The method of claim 4, wherein the enamel layer (31) is
-A transparent or colored sublayer 310 that is continuous and does not contain magnetizable particles 41, designed to be applied to the support, and
-At least one finishing layer 311 in which magnetizable particles 41 are dispersed, which is continuous and partially or completely covers the lower layer 310
The article comprising a. The method of claim 4, wherein the enamel layer (31) is
-A colored sublayer 310 in which magnetizable particles 41 are dispersed, designed to be continuous and applied to the support, and
-At least one transparent finishing layer 311 which is continuous and partially or completely covering the lower layer 310, in which magnetizable particles 41 are also dispersed
The article comprising a. The method of claim 4,
-Enamel layer (31)

A transparent or colored sublayer 310 that is continuous and does not contain magnetizable particles 41, designed to be applied to the support.

An intermediate layer 313 which is a colored layer or a magnetizable layer in which the magnetizable particles 41 are dispersed, and which is continuous and partially or completely covers the lower layer 310
Including,
-The intermediate layer 313 is

A first layer 321 of a continuous magnetizable brightener in which magnetizable particles 41 are dispersed, and

The second layer 322 of non-colored, transparent, and continuous brightener completely covering the first layer 321 of the magnetizable brightener
That is completely or partially covered by
Supplies. 12. The article of claim 11, wherein the enamel layer (31) further contains a silk screened or pad printed discontinuous outer enamel layer (33). 15. The article of claim 14, wherein the outer enamel layer (33) contains a circular filler that is stainless steel, copper, bronze or refractory steel beads. The article according to claim 1 or 2, wherein the support (2) is made of metal, glass or ceramic. The method of claim 1 or 2, wherein the cooking appliance, heating cover, or heating blender bowl of food or beverage manufacturing equipment, iron base, tableware such as trivet, radiator or wood stove, curling iron and straightening iron, towel Items that are rail or barbecue grills, boxes or tanks. A method of applying a protective coating (3) having at least one enamel layer (31) in which anisotropic particles (4, 41) are dispersed, to the support (2) of the heating article (1),
Characterized in that it comprises the step of orienting the anisotropic particles (41) by physical or mechanical means in at least one region (5) of the enamel layer (31). The method of claim 18,
a) providing a support (2);
b) applying at least one enamel composition in which anisotropic particles including magnetizable particles 41 are dispersed on one of the surfaces of the support 2 by pulverizing;
c) applying a magnetic field to orient the magnetizable particles 41 by magnetization, wherein the magnetization step c) is performed during step b) of applying the enamel composition to the support or immediately after the application step b) Phosphorus step; next
d) drying at a temperature between ambient temperature and 150° C.; next
e) firing at a temperature of at least 500°C.
How to include. The method of claim 19, wherein the applying step b) is
-b1) forming, on one of the sides of the support 2, an unfired sublayer 310 by pulverizing a transparent or colored enamel sublayer composition containing no magnetizable particles; next
-b2) forming an unfired enamel finish layer 311 by fine grinding of at least one finish enamel composition in which magnetizable particles 41 are dispersed on the unfired lower layer 310
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