WO2021129079A1

WO2021129079A1 - Preparation method for graphene modified aqueous non-stick coating capable of being used for iron cookware

Info

Publication number: WO2021129079A1
Application number: PCT/CN2020/122073
Authority: WO
Inventors: 钱涛; 刘海龙
Original assignee: 杭州吉华高分子材料股份有限公司; 钱涛
Priority date: 2019-12-27
Filing date: 2020-10-20
Publication date: 2021-07-01
Also published as: CN111100512A; CN111100512B; KR20220002669A; KR102459441B1

Abstract

A preparation method for a graphene modified aqueous non-stick coating capable of being used for iron cookware, comprising: 1) preparing graphene slurry from a plurality of layers of graphene; 2) performing interlayer blending on the graphene slurry and a zinc salt, performing reduction and heating reactions, adding tetraethyl orthosilicate, and performing reaction and filtration to obtain inorganic ceramic network in-situ modified zinc-containing graphene; and 3) pre-blending a fluorine-containing emulsion and tetraethyl orthosilicate, then adding the inorganic ceramic network in-situ modified zinc-containing graphene for reaction, and adding a bonding resin, a high-temperature resistant pigment filler, an assistant, and water so as to obtain a finished product. After film formation, the graphene modified aqueous non-stick coating has a good adhesive force with a coating substrate, can be used for iron cookware, and has the advantages of preventing heat accumulation, preventing corrosion, and being good in antibacterial property, good in durability, and strong in non-stickiness, and the like. Moreover, once a primary battery is electrochemically corroded, elemental zinc can be used as a sacrificial electrode to delay the corrosion of a base material, and a zinc-containing coating has a certain antibacterial property.

Description

Method for preparing graphene modified water-based non-stick coating for iron cookware

Technical field

The invention relates to the field of polymer materials, in particular to a method for preparing graphene modified water-based non-stick coatings that can be used for iron cookware.

Background technique

The existing water-based non-stick coatings are relatively mature in the application of aluminum cookware, but when used in iron cookware, it is still difficult to solve the inherent problem that iron cookware is prone to rust, so its use is limited. This is because iron cookware frequently comes into contact with acid, alkali, salt, water, oxygen and other media during the cooking process, forming a complex corrosive environment. When the moisture, oxygen or other ions in the corrosive media diffuse and immerse into the coating, When it reaches the surface of the ferrous metal substrate, it may electrochemically react with the ferrous metal and cause corrosion. Moreover, as the corrosion reaction progresses, the bonding force between the coating and the ferrous substrate will gradually weaken, which will cause the coating to fall off and lose the protective power of the ferrous substrate. Therefore, the protective ability of the coating depends more on its own resistance to penetration and barrier to corrosive media. It has also become an urgent need to improve the anti-corrosion performance of non-stick coatings applied to iron cookware.

Graphene is a two-dimensional honeycomb lattice structure composed of a single layer of carbon atoms densely packed. In single-layer graphene, each carbon atom forms a bond with surrounding carbon atoms ^{through sp 2 hybridization to form a regular hexagon.} It is precisely because of the special structure of graphene that it has high thermal stability, chemical stability and excellent resistance to permeation. It can effectively block the passage of gas atoms such as water and oxygen. Good physical barrier function.

Studies have found that the anti-corrosion effect of graphene is realized by multiple mechanisms such as shielding, hydrophobicity, and conductivity formed by its ultra-thin sheet structure. However, nano-scale graphene has poor compatibility with the coating resin, is easy to agglomerate, and is difficult to fully and stably disperse, and the agglomerated graphene cannot exert its due performance. In addition, it is difficult for commercially available graphene to achieve single-layer or oligo-layer (2-4 layers), and generally reach 10-50 layers. Although each layer can still maintain the characteristics of two-dimensional graphene, it has The graphene sheets with π-π interaction are prone to agglomeration, the specific surface area of the sheet is sharply reduced, and the barrier and protection performance of the substrate is significantly reduced. At the same time, the electrochemical properties in the graphene layer are not affected. Will accelerate the electrochemical corrosion of metals. Multilayer graphene is susceptible to damage and produces structural defects. From the perspective of electrochemical potential, damaged graphene acts as a positive electrode (C element) in the metal corrosion process, which will accelerate local electrochemical corrosion, especially when the Slight cracks or scratches appear in the coating, the corrosion rate of the exposed area is greatly accelerated, and the strength and toughness of the metal are reduced. Therefore, in order for graphene to give full play to its anti-corrosion properties in coatings, it must first solve the problem of its dispersion in resin and maintain the stability of the graphene structure.

Surface chemical modification of graphene can improve its compatibility and dispersibility with resin systems. Commonly used modified materials mainly include coupling agents and nano-inorganic fillers. However, this method can only coat and modify the surface of graphene, thereby overcoming the π-π interaction between graphene sheets and reducing the aggregation effect. However, because the preparation of single-layer graphene is extremely difficult, most of the commercially available ones are still The main layer of graphene is graphene. Even if the pre-dispersion treatment can break the agglomeration, it will not be dispersed into a single layer or oligo-layer, and the anti-corrosion effect of graphene cannot be effectively achieved.

Summary of the invention

In order to solve the above technical problems, the present invention provides a method for preparing graphene-modified water-based non-stick coatings that can be used for iron cookware. The present invention first processes the multilayer graphene so that the sheets are filled with elemental zinc. Then, the tetraethyl orthosilicate reaction is used for in-situ coating modification to form zinc-containing graphene with an inorganic ceramic network. After the inorganic ceramic network is obtained, it is mixed and reacted with tetraethyl orthosilicate and fluorine-containing emulsion to form an organic-inorganic interpenetrating network structure, so that the zinc-containing graphene is locked in the pores of the network structure, and the obtained graphite is prepared The graphene structure in the olefin-modified water-based non-stick coating will not be destroyed, and once electrochemical corrosion of the galvanic cell occurs, elemental zinc can be used as a sacrificial electrode to delay the corrosion of the substrate. At the same time, the zinc-containing coating has certain antibacterial properties.

The specific technical scheme of the present invention is:

A method for preparing graphene-modified water-based non-stick coating for iron cooking utensils, including the following steps:

1) Pre-dispersion of graphene: The multilayer graphene is dispersed in water through a pre-dispersion process to form a graphene slurry with a mass fraction of 0.5-25%.

2) Modification of graphene: blend the graphene slurry prepared in step 1) with zinc salt, vacuumize at room temperature to a vacuum degree of ≤10Pa, then replace with inert gas, vacuum and replace with inert gas several times After that, pressurize to 20-50MPa with inert gas, and then add reducing agent dropwise. After the addition is complete, the temperature is raised to 50-150℃, and the reaction is stirred at 10-50rpm for 5-60min. The pressure is adjusted to normal pressure, and silicon is added. Tetraethyl acid, adjust the pH to 1-4, stir and react for 2-5h at 200-300rpm at 40-80℃, and then filter to obtain the zinc-containing graphene modified in situ by the inorganic ceramic network; multilayer graphene, zinc and normal The mass ratio of tetraethyl silicate is 30-5:10-2:1.

3) Preparation of graphene-modified water-based non-stick coating: pre-mix the fluorine-containing emulsion and tetraethyl orthosilicate, and then add the in-situ modified zinc-containing graphene of the inorganic ceramic network prepared in step 2), at a temperature of 40-80 After stirring and reacting at 200-300rpm for 2-5h at ℃, add binder resin, high temperature resistant pigments and fillers, additives and water to obtain the finished product; the mass ratio of fluorine-containing emulsion, tetraethylorthosilicate and multilayer graphene is 50- 100:2-5:1.

The technical principle of the present invention is as follows:

First of all, through the pre-dispersion of graphene, the previously possible agglomerated nanoparticles are dispersed to facilitate modification. Next, the present invention exhausts the air in the interlayer gaps of the multi-layer graphene through vacuuming and inert gas replacement to prevent the elemental zinc generated in the gaps from being oxidized, and then pressurizes to fill the zinc salt To the gaps between the graphene layers, elemental zinc is generated between the layers under the action of the reducing agent to achieve the molecular level mixing of elemental zinc and graphene, and then fixed in the inorganic ceramic network structure formed by tetraethylorthosilicate. It not only reduces the aggregation effect between graphene sheets, but also protects the structure of zinc-containing graphene. Finally, the zinc-containing graphene modified in situ by the inorganic ceramic network is mixed and reacted with tetraethylorthosilicate and fluorine-containing emulsion In this process, further hydrolysis and condensation reactions occur, forming an interpenetrating network structure in which inorganic networks (ceramic networks) and organic networks (fluorine-containing emulsions) intersect each other. In this structure, zinc-containing graphene is locked in the pores of the network structure. Compared with pure surface chemical modification, it can not only avoid the agglomeration of graphene, but also fill the multi-layer graphene with molecular-level elemental zinc to enhance the anti-corrosion performance of the multi-layer graphene. The zinc-containing graphene can be networked The structure is anchored and mixed with the organic coating system, the uniform and stable dispersion state of zinc-containing graphene will not be changed, which can effectively improve the anti-corrosion performance and physical and mechanical properties of the coating. The specific schematic diagram of the above reaction process is shown in Figure 1.

In addition, in this coating, because the graphene layers are filled with molecular-level elemental zinc, the electrochemical electrons that can only be conducted in the graphene layers are transferred to the zinc that acts as a sacrificial anode throughout the graphene layers. Conduction reduces the effect of electrochemical corrosion. Metal cookware is often exposed to acid, salt and other media during use, especially iron cookware. In addition to common chemical corrosion, after cleaning, if the surface is not properly anti-corrosion barrier and residual moisture, it will be on the surface. A layer of electrochemical corrosion electrolyte solution is formed, which forms countless tiny galvanic cells with the iron and a small amount of carbon in the iron substrate. In these galvanic cells, iron is the negative electrode and carbon is the positive electrode. Iron loses electrons and is oxidized. Electrochemical corrosion is the main cause of iron corrosion. Multi-layer graphene modified coating is directly used. Multi-layer graphene is easily damaged and produces structural defects. From the perspective of electrochemical potential Look, the damaged graphene acts as a positive electrode (C element) in the metal corrosion process, which will accelerate local electrochemical corrosion, especially when the coating has slight cracks or scratches, the corrosion rate of the exposed area is greatly accelerated, and the metal is reduced. The strength and toughness of the performance. The zinc-containing graphene in the present invention is uniformly dispersed in the non-stick coating, firstly strengthens the tightness between the non-stick resins, effectively fills the gaps in the non-stick resin, and constitutes a good shielding effect, effectively It eases the entry of electrolyte solution and improves the corrosion resistance of the non-stick coating. In addition, the graphene structure fixed by the inorganic ceramic network structure is not easily damaged, and even if it is affected by electrochemical corrosion, the elemental zinc between the graphene layers can be As a sacrificial pole, it delays the corrosion of the substrate, and the zinc-containing coating has certain antibacterial properties.

In the solution of the present invention, it should be noted that the tetraethyl orthosilicate must be added in two parts, the first time is to form an inorganic ceramic network, and the second time is to realize the formation of an inorganic-organic interpenetrating network. Therefore, the special structure required by the present invention can be formed only by adding tetraethyl orthosilicate in two stages.

Preferably, in step 1), the multilayer graphene is commercially available graphene, and the number of layers is 10-50.

Preferably, in step 1), the pre-dispersion process is ultrasonic or grinding or adding a dispersant or a combination thereof.

Preferably, in step 2), the zinc salt is one or more of zinc sulfate, zinc chloride, zinc acetate, zinc nitrate and zinc carbonate.

Preferably, in step 2), the reducing agent is one or more of sodium citrate, sodium borohydride, glucose and ascorbic acid.

Preferably, in step 3), the fluorine-containing emulsion is one or more of PTFE, FEP, ECTFE, PCTFE and PFA.

Preferably, in step 3), the bonding resin is one or more of PES, PAI, PI and PPS.

Preferably, in step 3), the high temperature resistant pigments and fillers include high temperature resistant pigments and high temperature resistant fillers, the high temperature resistant pigments are inorganic high temperature resistant pigments or organic high temperature resistant pigments or a combination thereof, and the high temperature resistant fillers are ceramic powders. Or silicon carbide or a combination thereof.

Preferably, in step 3), the auxiliary agent is one or more of a dispersing agent, a leveling agent, a defoaming agent and a thickening agent.

Preferably, in step 3), the water is distilled water, ultrapure water or deionized water.

Compared with the prior art, the beneficial effects of the present invention are:

1. The present invention first uses vacuum-passing inert gas replacement to exhaust the air in the gaps between the multilayer graphene layers, and then pressurizes to fill the zinc salt into the gaps between the graphene layers, and in-situ reduction between the layers generates elemental substances Zinc realizes the molecular level mixing of graphene and elemental zinc between layers.

2. The present invention adopts the reaction of tetraethyl orthosilicate to form an inorganic ceramic network to realize the package modification of zinc-containing graphene, which not only avoids graphene agglomeration, but also realizes the structural protection of zinc-containing graphene.

3. After obtaining the zinc-containing graphene modified by the inorganic ceramic network, the present invention is mixed and reacted with tetraethyl orthosilicate and fluorine-containing emulsion to form an organic-inorganic interpenetrating network structure, so that the zinc-containing graphene is locked in When the pores of the network structure are affected by electrochemical corrosion, the elemental zinc between the graphene layers can be used as a sacrificial anode to delay the corrosion of the substrate, and the zinc-containing coating has certain antibacterial properties.

4. The synthesis method of the present invention is simple, convenient, and easy to industrialize. The obtained coating has good adhesion with the coating substrate after film formation. It is used on iron cookware and has anti-heat accumulation, anti-corrosion, good antibacterial properties and good durability. , Non-sticky and other advantages.

Reference number

Figure 1 is a schematic diagram of the reaction principle of the present invention.

Detailed ways

The present invention will be further described below in conjunction with embodiments.

General embodiment

The multilayer graphene is commercially available graphene, and the number of layers is 10-50. The pre-dispersion process is ultrasonic or grinding or adding a dispersant or a combination thereof.

2) Modification of graphene: blend the graphene slurry prepared in step 1) with zinc salt, vacuum at room temperature to a vacuum degree of ≤10Pa, replace with inert gas, vacuum and replace with inert gas 3 times After that, pressurize to 20-50MPa with inert gas, and then add reducing agent dropwise. After the addition is complete, the temperature is raised to 50-150℃, and the reaction is stirred at 10-50rpm for 5-60min. The pressure is adjusted to normal pressure, and silicon is added. Tetraethyl acid, adjust the pH to 1-4, stir and react for 2-5h at 40-80℃, 200-300rpm, and then filter to obtain in-situ modified zinc-containing graphene of inorganic ceramic network; multilayer graphene, zinc and normal The mass ratio of tetraethyl silicate is 30-5:10-2:1.

The zinc salt is one or more of zinc sulfate, zinc chloride, zinc acetate, zinc nitrate and zinc carbonate. The reducing agent is one or more of sodium citrate, sodium borohydride, glucose and ascorbic acid.

3) Preparation of graphene-modified water-based non-stick coating: pre-mix the fluorine-containing emulsion and tetraethyl orthosilicate, and then add the in-situ modified zinc-containing graphene of the inorganic ceramic network prepared in step 2), at a temperature of 40-80 ℃, 200-300rpm stirring reaction for 2-5h, adding binder resin, high temperature resistant pigments and fillers, additives and water to obtain the finished product; the mass ratio of fluorine-containing emulsion, tetraethylorthosilicate and multilayer graphene is 50- 100:2-5:1.

The fluorine-containing emulsion is one or more of PTFE, FEP, ECTFE, PCTFE and PFA. The bonding resin is one or more of PES, PAI, PI and PPS. The high temperature resistant pigments and fillers include high temperature resistant pigments and high temperature resistant fillers, the high temperature resistant pigments are inorganic high temperature resistant pigments or organic high temperature resistant pigments or a combination thereof, and the high temperature resistant filler is ceramic powder or silicon carbide or a combination thereof. The auxiliary agent is one or more of dispersing agent, leveling agent, defoaming agent and thickening agent. The water is distilled water, ultrapure water or deionized water.

Example 1

1) Pre-dispersion of graphene: adding a dispersant to the multilayer graphene and pre-dispersing in water to form a graphene slurry with a mass fraction of 0.5%.

2) Modification of graphene: blend the graphene slurry prepared in step 1) with zinc sulfate, vacuum at room temperature to a vacuum degree of ≤10Pa, and then replace with nitrogen. After repeated vacuum and nitrogen replacement 3 times, Nitrogen was pressurized to 20MPa, and then sodium citrate was added dropwise. After the addition was completed, the temperature was raised to 50°C, and the reaction was stirred at 10rpm for 60min. The pressure was adjusted to normal pressure, and tetraethylorthosilicate was added to adjust the pH to 4. After stirring and reacting at 80°C and 300 rpm for 2 hours, it was filtered to obtain zinc-containing graphene modified in situ by the inorganic ceramic network; the mass ratio of multilayer graphene, zinc and tetraethylorthosilicate was 5:2:1.

3) Preparation of graphene-modified water-based non-stick coating: pre-mix FTFE emulsion and tetraethyl orthosilicate, then add the in-situ modified zinc-containing graphene of inorganic ceramic network prepared in step 2) at 80°C, 300rpm After stirring and reacting for 2 hours, add PES, carbon black, silicon carbide, dispersant, leveling agent, thickener and water to obtain the finished product; the mass ratio of PTFE emulsion, tetraethylorthosilicate and multilayer graphene is 50: 2:1.

Example 2

1) Pre-dispersion of graphene: The multilayer graphene is pre-dispersed in water through a grinding and dispersion process to form a graphene slurry with a mass fraction of 25%.

2) Modification of graphene: blend the graphene slurry prepared in step 1) with zinc chloride, vacuumize at room temperature to a vacuum degree of ≤10Pa, and then argon replacement, vacuum and argon replacement repeatedly 3 After the second, pressurize argon to 50MPa, and then add sodium borohydride dropwise. After the addition is complete, heat up to 150℃, stir for 5min at 50rpm, adjust the pressure to normal pressure, add tetraethylorthosilicate, adjust the pH It is 1, after stirring and reacting for 5 hours at 40°C and 200 rpm, and then filtering to obtain zinc-containing graphene modified in situ by the inorganic ceramic network; the mass ratio of multilayer graphene, zinc and tetraethylorthosilicate is 30:10:1.

3) Preparation of graphene-modified water-based non-stick coating: pre-mix FTFE emulsion, ECTFE emulsion and tetraethyl orthosilicate, and then add the in-situ modified zinc-containing graphene of the inorganic ceramic network prepared in step 2). After stirring and reacting at 200 rpm for 5 hours, add PAI, iron red, silicon carbide, dispersant, leveling agent, defoamer and water to obtain the finished product; PTFE emulsion, ECTFE emulsion, tetraethyl orthosilicate and multilayer graphene The mass ratio is 80:20:5:1.

Example 3

1) Pre-dispersion of graphene: The multi-layer graphene is pre-dispersed in water through an ultrasonic dispersion process to form a graphene slurry with a mass fraction of 5%.

2) Modification of graphene: blend the graphene slurry prepared in step 1) with zinc acetate and zinc carbonate, vacuum at room temperature to a vacuum degree of ≤10Pa, then replace with nitrogen, vacuum and replace with nitrogen repeatedly 3 After the second, pressurize the nitrogen to 20MPa, and then add glucose dropwise. After the addition is complete, the temperature is raised to 80°C, the reaction is stirred at 30rpm for 30min, the pressure is adjusted to normal pressure, tetraethylorthosilicate is added, and the pH is adjusted to 1. After stirring and reacting for 4 hours at 60°C and 200 rpm, it was filtered to obtain zinc-containing graphene modified in situ by the inorganic ceramic network; the mass ratio of multilayer graphene, zinc and tetraethylorthosilicate was 20:5:1, zinc acetate and The mass ratio of zinc carbonate is 3:1.

3) Preparation of graphene-modified water-based non-stick coating: pre-mix PFA emulsion, PCTFE emulsion and tetraethyl orthosilicate, and then add the zinc-containing graphene modified in situ by the inorganic ceramic network prepared in step 2). After stirring and reacting at 200 rpm for 3 hours, add PES, PI, iron red, ceramic powder, dispersant, leveling agent, defoamer, thickener and water to obtain the finished product; PFA emulsion, PCTFE emulsion, tetraethylorthosilicate The mass ratio of ester to multilayer graphene is 50:30:3:1.

Example 4

1) Pre-dispersion of graphene: The multi-layer graphene is pre-dispersed in water through a grinding and dispersion process to form a graphene slurry with a mass fraction of 15%.

2) Modification of graphene: blend the graphene slurry prepared in step 1) with zinc nitrate, vacuum at room temperature to a vacuum degree of ≤10Pa, and then replace with nitrogen. After repeated vacuum and nitrogen replacement 3 times, Nitrogen was pressurized to 30MPa, and then ascorbic acid was added dropwise. After the addition was completed, the temperature was raised to 60℃, and the reaction was stirred at 20rpm for 15min. The pressure was adjusted to normal pressure. Tetraethylorthosilicate was added and the pH was adjusted to 2 at 60℃. , The reaction was stirred at 300 rpm for 3 hours and then filtered to obtain zinc-containing graphene modified in situ by the inorganic ceramic network; the mass ratio of multilayer graphene, zinc and tetraethyl orthosilicate was 10:2:1.

3) Preparation of graphene-modified water-based non-stick coating: pre-mix PTFE emulsion, FEP emulsion and tetraethyl orthosilicate, and then add the in-situ modified zinc-containing graphene of inorganic ceramic network prepared in step 2). After stirring and reacting at 300 rpm for 3 hours, add PPS, PAI, carbon black, ceramic powder, dispersant, leveling agent, defoamer, thickener and water to obtain the finished product; PTFE emulsion, FEP emulsion, tetraethylorthosilicate The mass ratio of ester to multilayer graphene is 60:20:5:1.

Comparative example 1

The only difference from Example 1 is that only the water-based non-stick coating is prepared without the addition of graphene, zinc and tetraethyl orthosilicate. The specific solution is: adding PES, carbon black, silicon carbide, dispersant, fluid to the PTFE emulsion A leveling agent, a thickening agent and water are used to obtain a water-based non-stick coating. The materials and composition are the same as those in Example 1.

Comparative example 2

The only difference from Example 1 is that in step 2), the graphene slurry is modified with a conventional silane coupling agent and does not contain zinc. The specific solution is: the graphene slurry prepared in step 1) is combined with KH560 After blending, 200rpm mechanical stirring and room temperature reaction for 2h, silane coupling agent modified graphene was obtained; the mass ratio of multilayer graphene to KH560 was 5:1. Other materials and composition are the same as in Example 1.

Comparative example 3

The only difference from Example 1 is that elemental zinc is not generated in the graphene sheet in step 2), and is not a molecular-level mixing. The specific solution is: blending the graphene slurry prepared in step 1) with zinc sulfate, Add sodium citrate dropwise. After the addition is complete, the temperature is raised to 50°C, and the reaction is stirred at 10rpm for 60min. Tetraethyl orthosilicate is added to adjust the pH to 4, and the reaction is stirred at 80°C, 300rpm for 2h, and then filtered to obtain a ceramic network. Modified zinc-containing graphene; the mass ratio of multilayer graphene, zinc and tetraethylorthosilicate is 5:2:1.

Comparative example 4

The only difference from Example 1 is that only tetraethyl orthosilicate is added in step 2), but not in step 3), and other materials and compositions are consistent with the embodiment.

The graphene modified water-based non-stick coatings prepared in Examples 1-4 and Comparative Examples 1-4 were respectively coated on iron pans (thickness 15-20μm), and then the hardness, heat buildup resistance and acid resistance were Tests for performance such as resistance, salt water resistance, antibacterial and non-stick properties, among which the hardness test is carried out according to GB/T 6739, the result is evaluated: paint film scratches; the heat accumulation test is carried out according to the induction cooker boiling water experiment, and the result is evaluated: boiled After water for 2 hours, observe with 4 times magnifying glass, the paint film has no cracks, wrinkles or peeling phenomenon; the acid resistance test is carried out according to the immersion method in GB/T 9274, the medium is 3% acetic acid solution, and the measurement is carried out according to GB /T 32095.2-2015 The surface abrasion resistance test is carried out after 5000 times. The acid resistance of the coating after abrasion; the salt water resistance test is carried out according to the immersion method in GB/T 9274, and the medium is a NaCl solution with a mass fraction of 10%. At the same time, the acid resistance of the coating after abrasion after 5000 times of the plane abrasion resistance test carried out according to GB/T 32095.2-2015 was measured; the antibacterial resistance test was carried out according to ISO 22196-2011, and the result was evaluated: for Staphylococcus aureus and large intestine The antibacterial efficacy value of bacilli is ≥2; the non-stickiness test is carried out according to GB/T 32095.2-2015. The result is evaluated: 10 fried eggs remain intact. The test results are shown in Table 1.

Table 1 Product performance test results of Examples 1-4 and Comparative Examples 1-4:

After inspection, comparative example 1 did not add graphene, zinc and tetraethyl orthosilicate, with low hardness, heat accumulation, poor acid and salt water resistance, severe corrosion on iron pans, and no antibacterial; while comparative example 2 added The graphene directly modified by the silane coupling agent does not contain zinc. The silane coupling agent can improve the dispersibility of the graphene and improve the hardness and heat resistance. However, the graphene modified by the silane coupling agent The compactness of the coating is not good. Although the acid and salt water resistance of the coating has been improved, it is still unqualified, and because it does not contain zinc, there is no antibacterial property; in Comparative Example 3, because elemental zinc is not in the graphene sheet Although the resulting coating has higher hardness, better salt water resistance, and antibacterial properties, the elemental zinc particles in the coating are larger and the free elemental zinc is unevenly dispersed, which will cause obvious problems in local areas. The heat accumulation phenomenon also significantly reduces the non-stickiness of the coating, and the coating cannot completely protect the substrate, and the local acid resistance is extremely poor; in Comparative Example 4, although the graphene has better dispersion and better structural stability, Because it does not form an interpenetrating network structure with the organic resin, the compactness of the coating is not good. Under the acidic medium with strong corrosiveness, after the wear resistance test, the abraded coating will still corrode. Compared with the comparative examples, the graphene modified water-based non-stick coatings of Examples 1-4 have excellent hardness, heat accumulation resistance, acid resistance, salt water resistance, acid resistance after grinding, salt water resistance after grinding, The antibacterial and non-stick properties indicate that the elemental zinc formed between graphene layers is mixed with graphene at the molecular level, and then the inorganic ceramic network formed by the reaction of tetraethylorthosilicate is used to coat and modify the zinc-containing graphene, which avoids graphite The agglomeration of ene can protect the structure of zinc-containing graphene, and through the formation of a ceramic network, an organic-inorganic interpenetrating network structure is formed between the zinc-containing graphene and the fluorine-containing macromolecular chain, and the combination between the two It is more compact and has a synergistic effect of ceramic materials, zinc, graphene, and non-stick resin.

The raw materials and equipment used in the present invention, unless otherwise specified, are all commonly used raw materials and equipment in the field; the methods used in the present invention, unless otherwise specified, are all conventional methods in the field.

The above are only preferred embodiments of the present invention and do not impose any limitation on the present invention. Any simple modifications, changes and equivalent transformations made to the above embodiments according to the technical essence of the present invention still belong to the technical solutions of the present invention. The scope of protection.

Claims

A method for preparing graphene modified water-based non-stick coating for iron cookware, which is characterized in that it comprises the following steps:

1) Pre-dispersion of graphene: The multi-layer graphene is dispersed in water through a pre-dispersion process to form a graphene slurry with a mass fraction of 0.5-25%;

2) Modification of graphene: blend the graphene slurry prepared in step 1) with zinc salt, vacuumize at room temperature to a vacuum degree of ≤10Pa, then replace with inert gas, vacuum and replace with inert gas several times After that, pressurize to 20-50MPa with inert gas, and then add reducing agent dropwise. After the addition is complete, the temperature is raised to 50-150℃, and the reaction is stirred at 10-50rpm for 5-60min. The pressure is adjusted to normal pressure, and silicon is added. Tetraethyl acid, adjust the pH to 1-4, stir and react for 2-5h at 200-300rpm at 40-80℃, and then filter to obtain the zinc-containing graphene modified in situ by the inorganic ceramic network; multilayer graphene, zinc and normal The mass ratio of tetraethyl silicate is 30-5:10-2:1;

3) Preparation of graphene-modified water-based non-stick coating: pre-mix the fluorine-containing emulsion and tetraethyl orthosilicate, and then add the in-situ modified zinc-containing graphene of the inorganic ceramic network prepared in step 2), at a temperature of 40-80 After stirring and reacting at 200-300rpm for 2-5h at ℃, add binder resin, high temperature resistant pigments and fillers, additives and water to obtain the finished product; the mass ratio of fluorine-containing emulsion, tetraethylorthosilicate and multilayer graphene is 50- 100:2-5:1.
The preparation method according to claim 1, wherein in step 1), the number of layers of the multilayer graphene is 10-50 layers.
The preparation method according to claim 1, wherein in step 1), the pre-dispersion process is ultrasonic or grinding or adding a dispersant or a combination thereof.
The preparation method according to claim 1, wherein in step 2), the zinc salt is one or more of zinc sulfate, zinc chloride, zinc acetate, zinc nitrate, and zinc carbonate.
The preparation method according to claim 1, wherein in step 2), the reducing agent is one or more of sodium citrate, sodium borohydride, glucose and ascorbic acid.
The preparation method according to claim 1, wherein in step 3), the fluorine-containing emulsion is one or more of PTFE, FEP, ECTFE, PCTFE and PFA.
The preparation method of claim 1, wherein in step 3), the bonding resin is one or more of PES, PAI, PI, and PPS.
The preparation method of claim 1, wherein in step 3): the high temperature resistant pigments and fillers include high temperature resistant pigments and high temperature resistant fillers; the high temperature resistant pigments are inorganic high temperature resistant pigments or organic high temperature resistant pigments or In combination, the high temperature resistant filler is ceramic powder or silicon carbide or a combination thereof.
The preparation method according to claim 1, wherein in step 3), the auxiliary agent is one or more of a dispersant, a leveling agent, a defoaming agent, and a thickening agent.
The preparation method according to claim 1, wherein in step 3), the water is distilled water, ultrapure water or deionized water.