Patent Description:
In traditional cooking appliance and household appliance industries, usually, a coating with a low surface tension or a low friction coefficient is sprayed on a surface of a product to make the product non-stick to food, for example, a non-stick coating can be sprayed. Existing non-stick coatings are mainly divided into two categories, one is a fluorocarbon coating with polytetrafluoroethylene (PTFE) as a main film-forming material, and the other is a silicon coating. The former PTFE coating is a linear polymer with a high molecular weight and a large volume, which leads to a low film compactness. In addition, the former has a low heat resistance (a long-term service temperature is only <NUM>), has some shortcomings in protecting a metal substrate, and since a coefficient of heat conductivity is only about <NUM> W/mK, a heating efficiency of the product is poor. For the latter organosilicon coating, although hardness can reach <NUM> or above, wear resistance and non-stickiness are poor. If a surface of the product is slightly worn, the non-stickiness will be greatly reduced, which cannot meet customer's expectation in use.

The fluorocarbon coating and the silicon coating each have low coefficients of heat conductivity, which leads to a low heating efficiency of a cooking appliance.

<CIT> discloses compositions comprising spherical graphene that can be used for coating cookware.

<CIT> discloses an enamel interlayer non-stick pan comprising a pan blank, a nano enamel coating and a non-stick coating, wherein the pan blank is sequentially coated with the nano enamel coating and the non-stick coating.

<CIT> discloses a graphene inner container for an electromagnetic cooking utensil. The graphene inner container comprises an inner container body and a graphene coating arranged on the inner wall and/or the outer wall of the inner container body.

<CIT> discloses a culinary article comprising a metal substrate having a concave inner face intended to be placed on the side of food which can be introduced into said article and a convex outer face intended to be placed facing a heat source, said inner face being coated in succession, starting from said substrate, with a hard enamel base, which is rough and contains no lead or cadmium, and then with a non-stick coating covering said hard layer.

<CIT> discloses a plasma non-stick pan comprising a pan body; a non-stick layer applied to the pan body; and a plasma layer provided between the non-stick layer and the pan body, wherein the plasma layer comprises a MCrAlY layer sprayed to the surface of the pan body and a mixture layer sprayed outside of the MCrAlY layer, the mixture layer being composed of MCrAlY particles and metal oxide particles.

The present disclosure aims at providing a cooking appliance. In the present disclosure, through graphene and/or graphene derivatives, heat conduction between a body and food is fully realized, and a heating speed and a heating uniformity are effectively improved.

According to the technical solutions disclosed herein, beneficial effects of the present disclosure include the following. In the present disclosure, the cooking appliance with the non-stick layer is prepared. Firstly, the primer layer is attached to the surface of the body of the cooking appliance, the graphene and/or graphene derivatives is tiled in order in the primer layer, and through orderly arrangement of the graphene and/or graphene derivatives, a graphene material is effectively guaranteed to give full play to a heat conductivity, and have uniform and fast heat conduction. In addition, graphene in the primer layer also has an excellent mechanical performance, the graphene cooperates with the uniformly rough structure of the body to effectively support the whole non-stick layer when the graphene is in the primer layer, and the sealing layer effectively protects the graphene. Compared with a traditional fluorocarbon coating, in the present disclosure, the non-stick layer has advantages of high surface hardness, great corrosion resistance, great durable wear resistance and non-stickiness, and long service life, and the non-stick layer is a durable wear resistance non-stick layer with more environmental protection, a high efficiency, and an excellent comprehensive performance. The present disclosure effectively ensures the firmness and the wear resistance of the product.

In the drawings: body <NUM>; non-stick layer <NUM>; primer layer <NUM>; sealing layer <NUM>; midcoat layer <NUM>; topcoat layer <NUM>.

In order to further explain the technical solution of the present disclosure, the following will describe the present disclosure in detail through specific implementations.

As illustrated in the figure, a cooking appliance is provided in the implementations, and includes a body <NUM> of the cooking appliance and a non-stick layer <NUM> coated on a surface of the body <NUM>. The non-stick layer <NUM> includes a primer layer <NUM> which is in contact with a side of the body <NUM>, and the primer layer <NUM> includes flake-like graphene and/or graphene derivatives uniformly distributed. A water-based paint configured to form the primer layer <NUM> has a mass fraction of graphene and/or graphene derivatives of <NUM>%~<NUM>%. The body <NUM> has a uniformly rough structure with a roughness of <NUM>~<NUM> at the side of the body <NUM> facing the non-stick layer <NUM>. The flake-like graphene and/or graphene derivatives has a radial width of <NUM>~<NUM>. The non-stick layer <NUM> has a thickness of <NUM>~<NUM>. Furthermore, as illustrated in <FIG>, in the non-stick layer <NUM>, a sealing layer <NUM>, a midcoat layer <NUM>, and a topcoat layer <NUM> are successively included above the primer layer <NUM>. A thickness distribution of each layer is illustrated in table <NUM>. The topcoat layer <NUM> may be an exterior-most or exteriorly exposed coating layer, and keep food from sticking and make cleanup a breeze. The midcoat layer <NUM> may be located between the topcoat layer <NUM> and the primer layer <NUM>, and protect against scratches and abrasion.

A method for preparing a cooking appliance is further provided in the implementations of the present disclosure, and includes following steps. A surface of a body of a cooking appliance is roughened. The surface of the body of the cooking appliance is roughened by sandblasting, and the body has a surface roughness of <NUM>~<NUM>. Before spraying the water-based paint, which includes the graphene and/or graphene derivatives and forms the primer layer, on the surface of the body, and after roughening the surface of the body of the cooking appliance, the cooking appliance is cleaned, which includes follows. The cooking appliance is cleaned by an alkaline solution at <NUM>~<NUM>, cleaned by clear water at room temperature for two times, cleaned by an acid solution at room temperature, cleaned by clear water at room temperature, and cleaned by pure water at room temperature, and stoving is performed on the cooking appliance at <NUM>.

A water-based paint, which includes graphene and/or graphene derivatives and forms a primer layer, is sprayed on the surface of the body, a sealing layer is sprayed on an undried surface of the primer layer, and baking is performed. After spraying the sealing layer on the undried surface of the primer layer, the baking is performed at <NUM>~<NUM> for <NUM>~<NUM>.

A midcoat layer and a topcoat layer are sprayed on a surface of the sealing layer in sequence and firing is performed, where the firing is performed at <NUM> for <NUM>~<NUM>, to obtain the cooking appliance with a target non-stick layer.

Main differences between implementation <NUM> and implementation <NUM> are illustrated in table <NUM> for details.

A coating used in a comparative example is a polytetrafluoroethylene (PTFE) coating in the related art.

Performance tests are performed on an identical kind of pan with non-stick layers obtained in implementations <NUM> to <NUM> and the comparative example, and specific test methods are as follows.

T1, wear resistance and durability (<NUM> kilogram (kg) dry grinding). Fix a sample to a rub tester. Put a Minnesota Mining and Manufacturing (<NUM>) 7447B scouring pad (<NUM> long and <NUM> wide) into the sample, press down the scouring pad with a force of <NUM>, and wipe back and forth on a surface of the sample at a speed of <NUM> times/minute. Change the scouring pad every <NUM> times, and record the number of times until a metal substrate is exposed.

T2, non-stickiness (fried eggs without oil). Place the sample on a flat electric furnace, dry burn and heat the sample, and when a temperature of a surface of an inner coating reaches <NUM>~<NUM>, put a fresh egg into the sample with a broken shell. When an egg white basically solidifies (a temperature on an inner surface of the sample shall not exceed <NUM>), directly pour out the egg without external force. Repeat the above non-stickiness test in T2, and record the number of eggs until an egg is poured out with external force.

T3, hardness test of coating. Place a STAEDTLER™ pencil on a No. <NUM> emery paper and grind a front end of a refill to make an edge of the refill sharp. Place the pencil on a pencil hardness tester correctly. Push the pencil hardness tester forward with a horizontal force, and scratch out a scratch with a length of about <NUM>~<NUM> on a coating surface to check whether the coating surface is broken by scratching. Reduce the pencil hardness from <NUM> to <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and H. Repeat the above hardness test in T3, until the coating surface is broken by scratching, and record the pencil hardness when the coating surface is broken by scratching.

T4, heat conduction uniformity. Use an infrared thermal imager to test heat conductivity. The more kinds of color images lead to the greater temperature differences, and the more irregular color image patterns lead to the more uneven temperatures.

T5, heat conduction speed. Put the obtained pan on an induction cooker for dry heating, record time when the temperature rises to <NUM>~<NUM>, record time when the temperature rises to <NUM>~<NUM>, and calculate heating-up time from <NUM> to <NUM>.

T6, corrosion resistance. Pour 10wt% saline into a sample, observe whether a coating surface is corroded at a fixed temperature, and record the time required for corrosion on the coating surface.

Specific performance test data are illustrated in table <NUM>.

In the present disclosure, the cooking appliance with the non-stick layer is prepared. Firstly, the primer layer is attached to the surface of the body of the cooking appliance, the graphene and/or graphene derivatives is tiled in order in the primer layer, and through orderly arrangement of the graphene and/or graphene derivatives, a graphene material is effectively guaranteed to give full play to a heat conductivity, and have uniform and fast heat conduction. In addition, graphene in the primer layer also has an excellent mechanical performance, the graphene cooperates with the uniformly rough structure of the body to effectively support the whole non-stick layer when graphene is in the primer layer, and the sealing layer effectively protects the graphene. Compared with a traditional fluorocarbon coating, in the present disclosure, the non-stick layer has advantages of high surface hardness, great corrosion resistance, great durable wear resistance and non-stickiness, and long service life, and the non-stick layer is a durable wear resistance non-stick layer with more environmental protection, a high efficiency, and an excellent comprehensive performance. The present disclosure effectively ensures the firmness and the wear resistance of the product.

Claim 1:
A cooking appliance, comprising a body (<NUM>) of the cooking appliance and a non-stick layer (<NUM>) coated on a surface of the body, wherein the non-stick layer comprises a primer layer (<NUM>) which is in contact with a side of the body, and the primer layer comprises flake-like graphene and/or graphene derivatives uniformly distributed,
characterized in that:
the non-stick layer further comprises a sealing layer (<NUM>) which is sprayed on an undried surface of the primer layer, wherein the non-stick layer further comprises a midcoat layer (<NUM>) and a topcoat layer (<NUM>) which are sprayed on a surface of the sealing layer in sequence.