Non-stick coating and preparation method thereof, non-stick inner pot and cooking utensil

Abstract

The present invention provides a non-stick coating and a preparation method thereof, a non-stick inner pot and a cooking utensil. In the direction away from the inner surface of the substrate, the non-stick coating includes a bottom layer, a middle layer and a surface layer covered in sequence; the material of the bottom layer includes PTFE, the material of the middle layer includes PFA, and the material of the surface layer includes PTFE and FEP. On the basis of the middle layer PFA, the present invention provides a special PTFE-FEP composite layer, which can improve the non-stick effect of the coating, and at the same time effectively improve the surface hardness of the non-stick coating, so that the non-stickiness and wear resistance of the coating are significantly improved, and the generation of scratches can be effectively reduced, greatly extending the service life of the non-stick coating.

Description

Technical Field

[0001] The invention relates to the technical field of electric heating appliances, and in particular to a non-stick coating and a preparation method thereof, a non-stick inner pot and a cooking utensil. Background Art

[0002] Currently, the non-stick coatings on the market mainly include PFA (perfluoroalkoxy), PTFE (polytetrafluoroethylene), ceramic coatings and PEEK (polyetheretherketone), etc. Among them, PFA has a smooth surface, low hardness, and is easily scratched; PTFE has poor corrosion resistance and ceramic coating has poor hydrolysis resistance, and both cannot meet the needs of long-term non-stick use.

[0003] In the prior art, patent CN 91112773.9 discloses a non-stick coating system with a concentration gradient, in which a mixed aqueous dispersion of perfluorocarbon resin and PAI is coated on a substrate, wherein the perfluorocarbon resin contains 50-90wt% PTFE and 10-50wt% PPVE-PFA, and both have a melt viscosity with a specific degree of differentiation, thereby increasing the non-stick performance. Patent CN 109077620 A discloses a non-stick coating, in which a ceramic layer is sprayed on a substrate, and then a PTFE-PFA composite layer is impregnated, and finally a non-stick coating is obtained by sintering. The above schemes can improve the non-stick performance of the coating to a certain extent, but they all have the problems of complex ingredients, cumbersome preparation, or inability to take into account both the non-stick performance and the hardness of the coating. Summary of the invention

[0004] The main purpose of the present invention is to provide a non-stick coating and a preparation method thereof, a non-stick inner pot and a cooking utensil, so as to solve the problem that the non-stick coating in the prior art cannot take into account both non-stick performance and coating hardness and has a short service life.

[0005] In order to achieve the above-mentioned purpose, according to one aspect of the present invention, a non-stick coating is provided, which includes a bottom layer, a middle layer and a surface layer covered in sequence in the direction away from the inner surface of the substrate; the material of the bottom layer includes PTFE, the material of the middle layer includes PFA, and the material of the surface layer includes PTFE and FEP.

[0006] Furthermore, the surface layer has ice cracks.

[0007] Furthermore, in the material of the surface layer, the mass ratio of PTFE to FEP is 1:(0.1-1).

[0008] Furthermore, the material of the surface layer also includes a solvent, and the solvent is one or more of water, butanol, n-hexanol and butyl ether; wherein, in the material of the surface layer, the mass ratio of PTFE to the solvent is 1:(0.05-0.3).

[0009] Furthermore, the size of a single piece of ice cracks in the surface layer is 0.05 to 20 mm.

[0010] Furthermore, the thickness T3 of the surface layer is 10-40 μm.

[0011] Furthermore, the thickness T2 of the middle layer is 30 to 70 μm.

[0012] Furthermore, the thickness T1 of the bottom layer is 10 to 25 μm.

[0013] Furthermore, the total thickness T of the non-stick coating is 50-135 μm.

[0014] According to another aspect of the present invention, a method for preparing the above-mentioned non-stick coating of the present invention is provided. The non-stick coating includes a bottom layer, a middle layer and a surface layer covered in sequence in a direction away from the inner surface of the substrate. The preparation method includes the following steps: step S1, performing a first coating on the inner surface of the substrate using a PTFE-containing liquid coating, and then drying to obtain a bottom layer; step S2, performing a second coating on the surface of the bottom layer using a PFA powder coating, and then performing a first sintering to obtain a middle layer; step S3, performing a third coating on the surface of the middle layer using a PTFE and FEP liquid coating, and then performing a second sintering to obtain a surface layer.

[0015] Furthermore, the surface layer has ice cracks.

[0016] Furthermore, in the material of the surface layer, the mass ratio of PTFE to FEP is 1:(0.1-1).

[0017] Furthermore, in step S1, before the first coating, a step of roughening the surface of the substrate on which the non-stick coating is to be provided is also included.

[0018] Furthermore, the roughening is performed by sandblasting, and after the roughening, the roughness Ra of the inner surface of the substrate is 2.0 to 3.5 μm.

[0019] Furthermore, in step S1, after roughening and before the first coating, a step of preheating the inner surface of the substrate is also included.

[0020] Furthermore, after preheating, the temperature of the inner surface of the substrate is 30-45°C.

[0021] Furthermore, in step S1, before the first coating, the process further includes: dispersing the PTFE-containing liquid coating at a speed of 30 to 50 rpm for 30 to 50 minutes, and then passing through a 150 to 200 mesh sieve.

[0022] Furthermore, in step S1, the first coating is sprayed by a compressed air spray gun, and the atomization pressure of the compressed air spray gun is 0.2-0.3 MPa.

[0023] Furthermore, in step S1, the drying temperature is 80-100° C. and the drying time is 10-20 min.

[0024] Furthermore, in step S2, before the second coating, the temperature of the bottom layer is also reduced to 20-30°C.

[0025] Furthermore, in step S2, the second coating is performed by electrostatic spraying, and the voltage of the electrostatic gun is 20 to 50 KV.

[0026] Furthermore, in step S2, the first sintering temperature is 390-410° C., and the time is 20-30 min.

[0027] Furthermore, in step S3, before the third coating, the temperature of the middle layer is also reduced to 20-30°C.

[0028] Furthermore, in step S3, before the third coating, the process further includes: dispersing the liquid coating containing PTFE and FEP at a speed of 30 to 50 rpm for 30 to 50 minutes, and then passing through a 100 to 150 mesh sieve.

[0029] Furthermore, in step S3, the third coating is sprayed by a compressed air spray gun, and the atomization pressure of the compressed air spray gun is 0.2-0.3 MPa.

[0030] Furthermore, in step S3, the second sintering temperature is 380-400° C., and the time is 15-25 min.

[0031] According to another aspect of the present invention, a non-stick inner pot is provided, comprising a substrate and a non-stick coating, wherein the non-stick coating is the non-stick coating of the present invention.

[0032] Further, the substrate includes one or more of aluminum, stainless steel, iron, titanium, enamel, carbon-based, graphite, ceramic, and glass.

[0033] Furthermore, the substrate is a composite sheet having at least two layers of material, and the layer close to the non-stick coating is one or more of aluminum, stainless steel, titanium, carbon-based, graphite, ceramic and glass.

[0034] According to another aspect of the present invention, a cooking utensil is provided, comprising the non-stick coating of the present invention, or comprising the non-stick inner pot of the present invention.

[0035] Furthermore, the cooking utensil is an induction cooker, an electric rice cooker or an electric pressure cooker.

[0036] By applying the technical solution of the present invention, the PTFE layer is used as the bottom layer of the non-stick coating, the PFA layer is used as the middle layer, and the PTFE-FEP composite layer is used as the surface layer, wherein the middle layer PFA can improve the overall density and corrosion resistance of the non-stick coating and extend the service life of the coating. At the same time, on the basis of the middle layer PFA, a special PTFE-FEP composite layer is provided, which can further improve the non-stick effect of the coating, and effectively improve the surface hardness of the non-stick coating, further significantly improve the non-stickiness and wear resistance of the coating, and can also effectively reduce the generation of scratches, greatly extending the service life of the non-stick coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0038] Figure 1 A schematic diagram of the structure of a non-stick coating according to Example 1 of the present invention is shown;

[0039] Figure 2 A process flow chart of preparing a non-stick coating according to Example 1 of the present invention is shown; and

[0040] Figure 3 A photograph of surface ice cracks according to Example 1 of the present invention is shown.

[0041] The above drawings include the following reference numerals:

[0042] 1. Base material; 2. Bottom layer; 3. Middle layer; 4. Surface layer. DETAILED DESCRIPTION

[0043] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0044] As described in the background of the present invention, the prior art has the problem that the non-stick coating cannot take into account both the non-stick performance and the coating hardness, and the service life is short. In order to solve the above problems, in a typical embodiment of the present invention, a non-stick coating is provided, and in the direction away from the inner surface of the substrate, the non-stick coating includes a bottom layer, a middle layer and a surface layer covered in sequence; the material of the bottom layer includes PTFE (polytetrafluoroethylene), the material of the middle layer includes PFA (perfluoroalkoxy), and the material of the surface layer includes PTFE and FEP (fluorinated ethylene propylene copolymer).

[0045] The present invention provides a special PTFE-FEP composite layer on the basis of the middle layer PFA, which can further improve the non-stick effect of the coating and effectively improve the surface hardness of the non-stick coating, so that the non-stickiness and wear resistance of the coating are significantly improved, and the generation of scratches can be effectively reduced, thereby taking into account good non-stick performance and appropriate coating hardness, and extending the service life of the non-stick coating.

[0046] In a preferred embodiment, the surface layer has ice cracks, thereby further improving the non-stickiness and wear resistance of the coating.

[0047] The inventor unexpectedly found in the research that if the mass ratio of FEP is too small, the viscosity will be limited and the most ideal ice crack effect cannot be obtained, and if the mass ratio is too large, the film-forming property and non-stickiness of the coating will be affected. Therefore, in a preferred embodiment, the mass ratio of PTFE and FEP in the surface layer material is 1: (0.1-1), so that a more suitable ice crack effect can be formed and the non-stickiness of the coating can be further improved.

[0048] The surface layer ice cracks can be composed of a plurality of irregular patterns, each of which is a single piece, and together form the shape of the ice cracks. In a preferred embodiment, the surface layer ice cracks have a single piece size of 0.05 to 20 mm, and the surface layer ice cracks with the above size can make the surface layer more non-stick, scratch-resistant and wear-resistant.

[0049] The composite material of the surface layer needs to have good homogeneity. In a preferred embodiment, the material of the surface layer also includes a solvent. The main function of the solvent in the surface layer is to disperse and mix PTFE and FEP. The solvent is one or more of water, butanol, n-hexanol and butyl ether, and has better solubility in the functional components PTFE and FEP of the surface layer of the present invention; wherein, in the material of the surface layer, the mass ratio of PTFE to solvent is 1:(0.05-0.3), preferably 1:(0.1-0.15), so as to achieve the best dispersion and mixing effect.

[0050] The non-stick coating needs to have a suitable thickness to improve performance while reducing dropouts and extending service life. In a preferred embodiment, the thickness T1 of the bottom layer is 10-25 μm, thereby providing better support thickness and bottom layer hardness.

[0051] Based on similar reasons, the thickness T2 of the middle layer is 30 to 70 μm, preferably 45 to 65 μm, so as to further improve the overall density and corrosion resistance of the non-stick coating and extend the service life of the coating.

[0052] Based on similar reasons, the thickness T3 of the surface layer is 10 to 40 μm, which can further significantly improve the non-stickiness and wear resistance of the coating and effectively reduce the occurrence of scratches.

[0053] For similar reasons, the total thickness T of the non-stick coating is 50-135 μm, preferably 65-105 μm, so as to better avoid the coating being too thin, resulting in a reduction in the non-stick performance and hardness of the coating, or being too thick, resulting in possible cracking of the coating, increasing the risk of coating falling off.

[0054] In another typical embodiment of the present invention, a method for preparing the above-mentioned non-stick coating is also provided. In the direction away from the inner surface of the substrate, the non-stick coating includes a bottom layer, a middle layer and a surface layer covered in sequence, and the preparation method includes the following steps: step S1, using a PTFE-containing liquid coating to perform a first coating on the inner surface of the substrate, and then drying to obtain a bottom layer; step S2, using a PFA powder coating to perform a second coating on the surface of the bottom layer, and then performing a first sintering to obtain a middle layer; step S3, using a PTFE and FEP liquid coating to perform a third coating on the surface of the middle layer, and then performing a second sintering to obtain a surface layer.

[0055] The present invention first applies a first coating on the inner surface of the substrate using a PTFE-containing liquid coating, and then dries it, thereby forming a PTFE bottom layer on the inner surface of the substrate; secondly, a second coating is applied on the bottom layer surface using a PFA powder coating, and a first sintering is performed, thereby forming a PFA middle layer on the surface of the PTFE bottom layer, and making it firmly bonded to the PTFE bottom layer; then, a third coating is applied on the surface of the middle layer using a PTFE and FEP-containing liquid coating, and a second sintering is performed, and a surface layer with high hardness and wear resistance is obtained through the viscosity-increasing effect of high-viscosity FEP. The above-mentioned preparation method is simple and fits the existing production line. The prepared non-stick coating can well balance good non-stick performance and suitable coating hardness, and has broad application prospects.

[0056] Wherein, the PTFE-containing liquid coating can be a state where PTFE is dispersed in water. In specific applications, as required, a water level line can also be printed on the dried bottom layer, and the water level line is printed on the bottom coating with a rubber head.

[0057] In a preferred embodiment, the surface layer has ice cracks, thereby further improving the non-stickiness and wear resistance of the prepared coating.

[0058] In a preferred embodiment, in the material of the surface layer, the mass ratio of PTFE to FEP is 1:(0.1-1), so that a more suitable ice crack effect can be formed on the surface of the prepared surface layer, further improving the non-stick properties of the coating.

[0059] In a preferred embodiment, in step S1, before the first coating, a step of roughening the inner surface of the substrate (ie, the surface of the substrate on which the non-stick coating is to be provided) is also included to enhance the adhesion of the subsequent coating.

[0060] For the purpose of facilitating the adhesion of the coating, in a preferred embodiment, the roughening is performed by sandblasting, which is easier to operate and has a more uniform coating effect. After the roughening, the roughness Ra of the inner surface of the substrate is 2.0 to 3.5 μm.

[0061] In a preferred embodiment, in step S1, after roughening and before the first coating, a step of preheating the inner surface of the substrate is also included to enhance the adhesion of subsequent coatings.

[0062] In a preferred embodiment, after preheating, the temperature of the inner surface of the substrate is 30-45° C., which is more convenient for the subsequent coating to adhere.

[0063] In a preferred embodiment, in step S1, before the first coating, the process further includes: dispersing the PTFE-containing liquid coating at a speed of 30 to 50 rpm for 30 to 50 minutes, and then passing through a 150 to 200 mesh sieve, so that the liquid coating is more homogeneous and is more convenient for improving the uniformity of the subsequent coating process.

[0064] In order to further take into account the coating properties, productivity and cost, in a preferred embodiment, in step S1, the first coating is sprayed using a compressed air spray gun, and the atomization pressure of the compressed air spray gun is 0.2-0.3 MPa.

[0065] In a preferred embodiment, in step S1, the drying temperature is 80-100°C and the drying time is 10-20 minutes, so that the solvent in the PTFE-containing liquid coating evaporates and the bonding between PTFE and the substrate surface is more firmly established.

[0066] In a preferred embodiment, step S2 further includes a step of reducing the temperature of the bottom layer to 20-30° C. before the second coating, so as to provide a more suitable surface environment for the subsequent middle layer coating.

[0067] In order to further improve the non-stick properties of the coating and the uniformity of the coating, in a preferred embodiment, in step S2, the second coating is performed by electrostatic spraying, and the voltage of the electrostatic gun is 20 to 50 KV.

[0068] If the sintering temperature is not high enough, the overall scratch resistance and non-stick performance of the coating may be affected; if the temperature is too high, the coating may be carbonized, resulting in a reduced service life. Therefore, in a preferred embodiment, in step S2, the first sintering temperature is 390-410°C and the time is 20-30 minutes.

[0069] In a preferred embodiment, step S3 further includes a step of reducing the temperature of the middle layer to 20-30° C. before the third coating, so as to provide a more suitable surface environment for subsequent surface coating.

[0070] In a preferred embodiment, in step S3, before the third coating, it also includes: dispersing the PTFE and FEP liquid coating at a speed of 30 to 50 rpm for 30 to 50 minutes, and then passing through a 100 to 150 mesh sieve, so that the liquid coating is more homogeneous and easier to improve the uniformity of the subsequent coating process.

[0071] Based on similar reasons as the first coating, in a preferred embodiment, in step S3, the third coating is sprayed using a compressed air spray gun, and the atomization pressure of the compressed air spray gun is 0.2-0.3 MPa.

[0072] Based on similar reasons as the first sintering, in a preferred embodiment, in step S3, the temperature of the second sintering is 380-400° C., and the time is 15-25 min.

[0073] In another typical embodiment of the present invention, a non-stick inner pot is provided, comprising a substrate and a non-stick coating, wherein the non-stick coating is the non-stick coating described above in the present invention.

[0074] The substrate can be any conventional substrate in the art. In order to further improve the bonding strength between the substrate and the non-stick coating, in a preferred embodiment, the substrate includes one or more of aluminum, stainless steel, iron, titanium, enamel, carbon-based, graphite, ceramic, and glass.

[0075] In a preferred embodiment, the substrate is a composite sheet having at least two layers of materials, and the layer close to the non-stick coating is one or more of aluminum, stainless steel, titanium, carbon-based, graphite, ceramic and glass. The above substrate can be more conveniently and flexibly adjusted according to the needs of different usage scenarios, and the combination effect of the substrate and the specific non-stick coating of the present invention is better.

[0076] In another typical embodiment of the present invention, a cooking utensil is provided, comprising the non-stick coating of the present invention, or comprising the non-stick inner pot of the present invention, so that the cooking utensil has good non-stick performance and appropriate hardness, good use effect and long service life.

[0077] In a preferred embodiment, the cooking appliance includes but is not limited to an induction cooker, an electric rice cooker or an electric pressure cooker, and can be flexibly adjusted according to the needs of different usage scenarios.

[0078] Typically but not limiting, in the material of the surface layer, the mass ratio of PTFE to FEP is 1:0.1, 1:0.13, 1:0.15, 1:0.2, 1:0.25, 1:0.3, 1:0.35, 1:0.4, 1:0.45, 1:0.5, 1:0.55, 1:0.6, 1:0.65, 1:0.7, 1:0.75, 1:0.8, 1:0.85, 1:0.9, 1:0.95, 1:1 or a range consisting of any two ratios thereof.

[0079] Typically but not limiting, in the material of the surface layer, the mass ratio of PTFE to solvent is 1:0.05, 1:0.1, 1:0.13, 1:0.15, 1:0.2, 1:0.25, 1:0.3 or a range consisting of any two ratios thereof.

[0080] Typically but not limiting, the ice cracks in the surface layer have a single piece size of 0.05mm, 0.1mm, 0.5mm, 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, 16mm, 17mm, 18mm, 19mm, 20mm or a range consisting of any two of them.

[0081] Typically but not limitatively, in the above-mentioned non-stick coating of the present invention, the thickness T1 of the bottom layer is 10 μm, 12 μm, 14 μm, 16 μm, 18 μm, 20 μm, 22 μm, 24 μm, 25 μm or a range consisting of any two of them.

[0082] Typically but not limitatively, in the non-stick coating of the present invention, the thickness T2 of the middle layer is 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm or a range consisting of any two of them.

[0083] Typically but not limitatively, in the above non-stick coating of the present invention, the thickness T3 of the surface layer is 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm or a range consisting of any two of them.

[0084] Typically but not limitatively, in the above-mentioned non-stick coating of the present invention, the total thickness T of the non-stick coating is 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, 105 μm, 110 μm, 115 μm, 120 μm, 125 μm, 130 μm, 135 or a range consisting of any two of them.

[0085] Typically but not limitatively, in the method for preparing the non-stick coating of the present invention, in step S1, the drying temperature is 80° C., 85° C., 90° C., 95° C., 100° C. or a range consisting of any two of them; the drying time is 10 min, 12 min, 14 min, 16 min, 18 min, 20 min or a range consisting of any two of them.

[0086] Typically but not limitatively, in the method for preparing the non-stick coating of the present invention, in step S2, the temperature of the first sintering is 390° C., 395° C., 400° C., 405° C., 410° C. or a range consisting of any two of them; the time is 20 min, 22 min, 24 min, 26 min, 28 min, 30 min or a range consisting of any two of them.

[0087] Typically but not limitatively, in the method for preparing the non-stick coating of the present invention, in step S3, the temperature of the second sintering is 380° C., 385° C., 390° C., 395° C., 400° C. or a range consisting of any two of them; the time is 15 min, 17 min, 19 min, 21 min, 23 min, 25 min or a range consisting of any two of them.

[0088] The present application is further described in detail below in conjunction with specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in the present application.

[0089] Example 1

[0090] Embodiment 1 provides a non-stick inner pot.

[0091] Base material: aluminum alloy;

[0092] In the direction away from the inner surface of the substrate (i.e., the side close to the food cooking), the non-stick coating includes a bottom layer, a middle layer, and a surface layer. The bottom layer material: a PTFE liquid coating (PTFE dispersed in deionized water);

[0093] Middle layer material: containing PFA powder coating;

[0094] Surface material: liquid coating containing PTFE and FEP: PTFE, FEP and deionized water are mixed in a mass ratio of 0.6:0.32:0.08.

[0095] Step S1, sandblasting the inner surface of the substrate near the food cooking, the inner surface roughness Ra of the substrate is 2.5μm; then preheating, the temperature of the inner surface of the substrate is 35℃; disperse the PTFE-containing liquid coating at a speed of 40rpm for 40min, then pass through a 150-200 mesh sieve, and spray it on the inner surface of the substrate using a compressed air spray gun with an atomization pressure of 0.25MPa; then dry it at a temperature of 90℃ for 15min to obtain a bottom layer with a thickness T1 of 20μm. Print the water level line on the dried bottom layer, and print the ink on the bottom coating with a rubber head.

[0096] Step S2, coating the surface of the bottom layer with a PFA powder coating by electrostatic spraying, with the voltage of the electrostatic gun being 35KV; and then sintering, with the sintering temperature being 400°C and the time being 25min, to obtain a middle layer with a thickness T2 of 50μm.

[0097] Step S3, disperse the PTFE and FEP liquid coating at a speed of 40 rpm for 40 minutes, then pass through a 100-150 mesh sieve, and spray it on the surface of the middle layer using a compressed air spray gun with an atomization pressure of 0.25 MPa; then sinter, the sintering temperature is 390° C., the time is 20 minutes, and the surface layer is obtained, the thickness T3 is 25 μm, the surface has ice cracks, and the single piece size (the diameter of the irregular pattern) is 0.5-10 mm. The total thickness T of the non-stick coating is 95 μm.

[0098] Among them, the single piece size specifically refers to the maximum length of the line segment formed between two points on the edge of a single piece in the irregular figure that constitutes the ice crack and passes through the geometric center. The single piece size is related to the thickness of the surface layer. The smaller the thickness, the smaller the single piece size.

[0099] Example 1 Non-stick coating structure schematic diagram of non-stick inner pot Figure 1 , the process flow chart of non-stick coating preparation is shown in Figure 2 , photos of surface ice cracks can be found at Figure 3 .

[0100] Example 2

[0101] Embodiment 2 provides a non-stick inner pot.

[0102] Base material: aluminum alloy;

[0103] In the direction away from the inner surface of the substrate (i.e., the side close to the food cooking), the non-stick coating includes a bottom layer, a middle layer, and a surface layer. The bottom layer material: contains PTFE liquid coating (PTFE dispersed in water);

[0104] Middle layer material: containing PFA powder coating;

[0105] Surface material: liquid coating containing PTFE and FEP: PTFE, FEP and deionized water are mixed in a mass ratio of 0.8:0.1:0.1.

[0106] Step S1, sandblasting the inner surface of the substrate near the food cooking, the inner surface roughness Ra of the substrate is 2.0μm; then preheating, the temperature of the inner surface of the substrate is 45℃; disperse the PTFE-containing liquid coating at a speed of 30rpm for 50min, then pass through a 150-200 mesh sieve, and spray it on the inner surface of the substrate using a compressed air spray gun with an atomization pressure of 0.2MPa; then dry it at a temperature of 80℃ for 20min to obtain a bottom layer with a thickness T1 of 10μm. Print the water level line on the dried bottom layer, and print the ink on the bottom coating with a rubber head.

[0107] Step S2, coating the surface of the bottom layer with a PFA powder coating by electrostatic spraying, with the voltage of the electrostatic gun being 20 KV; and then sintering, with the sintering temperature being 390° C. for 30 min, to obtain a middle layer with a thickness T2 of 30 μm.

[0108] Step S3, disperse the PTFE and FEP liquid coating at a speed of 30 rpm for 50 minutes, then pass through a 100-150 mesh sieve, and spray it on the surface of the middle layer using a compressed air spray gun with an atomization pressure of 0.2 MPa; then sinter, the sintering temperature is 380°C, the time is 25 minutes, and the surface layer is obtained, the thickness T3 is 10 μm, and the surface has ice cracks, wherein the diameter of the irregular pattern is 0.05-1 mm. The total thickness T of the non-stick coating is 50 μm.

[0109] Example 3

[0110] Embodiment 3 provides a non-stick inner pot.

[0111] Base material: aluminum alloy;

[0112] In the direction away from the inner surface of the substrate (i.e., the side close to the food cooking), the non-stick coating includes a bottom layer, a middle layer, and a surface layer. The bottom layer material: contains PTFE liquid coating (PTFE dispersed in water);

[0113] Middle layer material: containing PFA powder coating;

[0114] Surface material: liquid coating containing PTFE and FEP: PTFE, FEP and deionized water are mixed in a mass ratio of 0.48:0.47:0.05.

[0115] Step S1, sandblasting is performed on the inner surface of the substrate near the food cooking, and the inner surface roughness Ra of the substrate is 3.5μm; then preheating is performed, and the temperature of the inner surface of the substrate is 30°C; the PTFE-containing liquid coating is dispersed at a speed of 50rpm for 30min, and then passed through a 150-200 mesh sieve, and sprayed on the inner surface of the substrate using a compressed air spray gun, and the atomization pressure is 0.3MPa; then drying is performed, and the drying temperature is 100°C, and the time is 10min, to obtain a bottom layer, and the thickness T1 is 25μm. The water level line is printed on the dried bottom layer, and the water level line is printed on the bottom coating with a rubber head.

[0116] Step S2, coating the surface of the bottom layer with a PFA powder coating by electrostatic spraying, with the voltage of the electrostatic gun being 50 KV; and then sintering, with the sintering temperature being 410° C. for 20 min, to obtain a middle layer with a thickness T2 of 70 μm.

[0117] Step S3, disperse the PTFE and FEP liquid coating at a speed of 50 rpm for 30 minutes, then pass through a 100-150 mesh sieve, and spray it on the surface of the middle layer using a compressed air spray gun with an atomization pressure of 0.3 MPa; then sinter at a temperature of 400°C for 15 minutes to obtain a surface layer with a thickness T3 of 40 μm and ice cracks on the surface, wherein the diameter of the irregular pattern is 10-20 mm. The total thickness T of the non-stick coating is 135 μm.

[0118] Comparative Example 1

[0119] The difference between Comparative Example 1 and Example 1 is that the surface layer material is a coating in which PTFE and deionized water are mixed in a mass ratio of 0.9:0.1.

[0120] Comparative Example 2

[0121] The difference between Comparative Example 2 and Example 1 is that no surface layer spraying is performed.

[0122] Comparative Example 3

[0123] The difference between Comparative Example 3 and Example 1 is that a Teflon non-stick layer is sprayed on the inner surface of the substrate.

[0124] Comparative Example 4

[0125] Example 1 of Chinese patent CN 91112773.9.

[0126] Comparative Example 5

[0127] (1) Pre-treating the aluminum pot substrate, wherein the pre-treating method comprises: a) degreasing at 55° C. for 8 minutes; b) washing with deionized water; c) drying at 100° C. for 5 minutes; d) using 60-80 mesh brown steel sand to sandblast the surface of the aluminum pot substrate at a jet air pressure of 0.6 MPa to make its surface roughness Ra 3 μm, and then using air flow to blow away the powder particles remaining on the surface of the pot substrate; e) alkaline washing with 40 wt % NaOH solution at 80° C. for 1 minute; f) neutralizing with 20 wt % nitric acid solution for 3 minutes; g) washing with deionized water and drying at 300° C. for 12 minutes;

[0128] (2) preheating the surface of the substrate obtained in step (1) to 120° C.

[0129] (3) Plasma spraying treatment is performed on a mixed powder of aluminum oxide powder and titanium oxide powder to form a composite coating of aluminum oxide and titanium oxide on a substrate, wherein the content of titanium oxide powder is 5% by weight and the content of aluminum oxide powder is 95% by weight based on the weight of the mixed powder; the conditions of the plasma spraying treatment include: a spraying power of 40 kW, a spraying distance of 90 mm, a spraying angle of 75°±1°, a spraying current of 680 A, a spraying thickness of 200 μm, argon as the main gas, hydrogen as the auxiliary gas, a hydrogen flow rate of 6 L / min, and an argon flow rate of 40 L / min.

[0130] (4) Preparation of PTFE sol: 12 ml of epoxy acrylate, 8 ml of anhydrous ethanol, 8 ml of acetone and 12 ml of deionized water were mixed to obtain a mixed solution; 62 ml of PTFE emulsion was dropped into the mixed solution, ultrasonically shaken and stirred for 12 min, and then 15 ml of acidic SiO2 sol (SiO2 concentration is 25 wt%), 0.8 ml of silane coupling agent KH-550 and 1.5 ml of epoxy resin were added, ultrasonically shaken and stirred for 18 min, and allowed to react at 25°C for 1.2 h to obtain PTFE sol.

[0131] (5) immersing the substrate obtained in step (3) in the PTFE sol for 8 minutes, and then performing a uniform pulling treatment at a pulling speed of 4 cm / min to form a PTFE layer;

[0132] (6) The substrate obtained in step (5) was first dried at 30°C for 4 hours, and then heated at 85°C for 12 hours to obtain a PTFE layer with a thickness of 25 μm.

[0133] The non-stick coatings in the above examples and comparative examples were tested for hardness, non-stick performance and lifespan. The results are shown in Tables 1 and 2.

[0134] Test method:

[0135] Hardness: GB / T 6739-2006.

[0136] Non-stick performance: GB / T32095.2-2015.

[0137] Life test: Enterprise standard Q / SPE J07002-2016.

[0138] Table 1

[0139]

[0140]

[0141] Table 2

[0142]

[0143] It can be seen from the above that, compared with the comparative example, each embodiment of the present invention is provided with a special PTFE corrugated composite layer on the basis of the middle layer PFA, thereby effectively improving the surface hardness of the non-stick coating, and the pencil hardness is increased from 2B to 1H~3H; at the same time, by adding FEP, the viscosity of the coating is increased, its fluidity is reduced, and an ice crack effect is formed, which can significantly improve the non-stickiness and wear resistance of the coating, and can also effectively reduce the generation of scratches, thereby taking into account good non-stick performance and appropriate coating hardness, and extending the service life of the non-stick coating.

[0144] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A non-stick coating, characterized in that: In the direction away from the inner surface of the substrate, the non-stick coating includes a bottom layer, a middle layer and a surface layer covered in sequence; The material of the bottom layer includes PTFE, the material of the middle layer is a PFA powder coating, and the material of the surface layer includes PTFE and FEP; The surface layer has ice cracks, and the size of a single piece of the ice cracks is 0.05 to 20 mm; the material of the surface layer is The mass ratio of PTFE to FEP is 1:(0.1~1).

2. The non-stick coating according to claim 1, characterized in that The material of the surface layer also includes a solvent, and the solvent is one or more of water, butanol, n-hexanol and butyl ether; Wherein, in the material of the surface layer, the mass ratio of PTFE to the solvent is 1:(0.05-0.3).

3. The non-stick coating according to claim 1 or 2, characterized in that: The thickness T3 of the surface layer is 10-40 μm.

4. The non-stick coating according to claim 1 or 2, characterized in that: The thickness T2 of the middle layer is 30-70 μm.

5. The non-stick coating according to claim 1 or 2, characterized in that: The thickness T1 of the bottom layer is 10-25 μm.

6. The non-stick coating according to claim 1 or 2, characterized in that: The total thickness T of the non-stick coating is 50-135 μm.

7. A preparation method, characterized in that: For preparing the non-stick coating according to any one of claims 1 to 6, the non-stick coating comprises a bottom layer, a middle layer and a surface layer covered in sequence in a direction away from the inner surface of the substrate, and the preparation method comprises the following steps: Step S1, performing a first coating on the inner surface of the substrate using a PTFE-containing liquid coating, and then drying the coating to obtain the bottom layer; Step S2, performing a second coating on the surface of the bottom layer using a PFA powder coating, and then performing a first sintering to obtain the middle layer; Step S3, performing a third coating on the surface of the middle layer using a liquid coating containing PTFE and FEP, and then performing a second sintering to obtain the surface layer.

8. The preparation method according to claim 7, characterized in that: In the step S1, before the first coating, a step of roughening the inner surface of the substrate is also included.

9. The preparation method according to claim 8, characterized in that: The roughening is performed by sandblasting. After the roughening, the roughness Ra of the inner surface of the substrate is 2.0 to 3.5 μm.

10. The preparation method according to claim 8, characterized in that: In the step S1, after the roughening and before the first coating, the step of preheating the inner surface of the substrate is also included.

11. The preparation method according to claim 10, characterized in that: After the preheating, the temperature of the inner surface of the substrate is 30-45°C.

12. The preparation method according to claim 7, characterized in that: In the step S1, before the first coating, the process further comprises: dispersing the PTFE-containing liquid coating at a speed of 30 to 50 rpm for 30 to 50 minutes, and then passing through a 150 to 200 mesh sieve.

13. The preparation method according to claim 7, characterized in that: In the step S1, the first coating is sprayed by a compressed air spray gun, and the atomization pressure of the compressed air spray gun is 0.2-0.3 MPa.

14. The preparation method according to claim 7, characterized in that: In the step S1, the drying temperature is 80-100° C. and the drying time is 10-20 minutes.

15. The preparation method according to claim 7, characterized in that: In the step S2, before the second coating, the temperature of the bottom layer is also reduced to 20-30°C.

16. The preparation method according to claim 7, characterized in that: In the step S2, the second coating is performed by electrostatic spraying, and the voltage of the electrostatic gun is 20-50 KV.

17. The preparation method according to claim 7, characterized in that: In the step S2, the first sintering temperature is 390-410° C. and the time is 20-30 min.

18. The preparation method according to claim 7, characterized in that: In the step S3, before the third coating, the temperature of the middle layer is also reduced to 20-30°C.

19. The preparation method according to claim 7, characterized in that: In the step S3, before the third coating, the method further comprises: dispersing the liquid coating containing PTFE and FEP at a speed of 30 to 50 rpm for 30 to 50 minutes, and then passing through a 100 to 150 mesh sieve.

20. The preparation method according to claim 7, characterized in that: In the step S3, the third coating is sprayed by a compressed air spray gun, and the atomization pressure of the compressed air spray gun is 0.2-0.3 MPa.

21. The preparation method according to claim 7, characterized in that: In the step S3, the second sintering temperature is 380-400° C. and the time is 15-25 minutes.

22. A non-stick inner pot, comprising a substrate and a non-stick coating, characterized in that: The non-stick coating is the non-stick coating according to any one of claims 1 to 6.

23. The non-stick inner pot according to claim 22, characterized in that: The substrate includes one or more of aluminum, stainless steel, iron, titanium, enamel, carbon-based, ceramic, and glass.

24. The non-stick inner pot according to claim 23, characterized in that: The substrate is a composite sheet having at least two layers of materials, and the layer close to the non-stick coating is one or more of aluminum, stainless steel, titanium, carbon-based, ceramic and glass.

25. A cooking utensil, characterized in that: A non-stick coating according to any one of claims 1 to 6, or a non-stick inner pot according to any one of claims 22 to 24.

26. The cooking appliance according to claim 25, characterized in that The cooking utensil is an induction cooker, an electric rice cooker or an electric pressure cooker.

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