A Teflon composite coating and cookware comprising the coating

Abstract

The present invention relates to a Teflon composite coating, and more particularly to a Teflon composite coating and cookware comprising the coating. The Teflon composite coating comprises a surface layer and a bottom layer, wherein the surface layer comprises polytetrafluoroethylene, and the bottom layer comprises a graft copolymer of polyethersulfone and polyoxazoline. The Teflon composite coating of the present invention has good metal adhesion and a low yellowness index. Its application to cookware can improve the durability and aesthetics of the coating or cookware.

Description

Technical Field

[0001] The invention relates to a Teflon coating, in particular to a Teflon composite coating and a cooker comprising the coating. Background Art

[0002] Teflon nonstick pans are a common cooking utensil. Coated with Teflon (PTFE), they resist food adhesion and are easy to clean. However, due to Teflon's poor adhesion to metal surfaces, the coating is applied to the cookware surface in multiple layers during the manufacturing process, including a base coat, an intermediate coat, and a top coat, to ensure durability and anti-stick properties.

[0003] The most common Teflon nonstick coating consists of a topcoat of polytetrafluoroethylene (PTFE), a middlecoat of polyamide-imide (PAI), and a bottomcoat of polyethersulfone (PES). PES offers excellent heat resistance and adhesion to metal surfaces, allowing it to bond tightly to the base material of the cookware, providing excellent adhesion and durability, ensuring the coating will not easily fall off during long-term use. However, due to the poor adhesion between PES and PTFE, a PAI middle layer is required to bond the two together. This multi-layer structure complicates the manufacturing process, and over time, problems such as coating shedding and yellowing may occur, impacting the lifespan and appearance of the cookware.

[0004] In addition, due to the hydrophobic nature of polyethersulfone, coatings with polyethersulfone as the main component basically require the use of organic solvents as diluents. The large-scale use of organic solvents not only leads to high production costs but also causes environmental pollution. In this case, in order to enhance the compatibility of polyethersulfone with polytetrafluoroethylene, polyethersulfone needs to be ground into ultrafine powder, but this increases the operating steps and production costs. Summary of the Invention

[0005] To overcome at least one defect of the above-mentioned prior art, in a first aspect, the present invention provides a Teflon composite coating comprising a surface layer and a bottom layer, wherein the surface layer comprises polytetrafluoroethylene, and the bottom layer comprises a graft copolymer of polyethersulfone and polyoxazoline.

[0006] In one embodiment, the graft copolymer includes a polyethersulfone backbone and polyoxazoline side chains grafted to the polyethersulfone backbone.

[0007] In one embodiment, the weight average molecular weight of the polyethersulfone main chain is 50,000 to 120,000 g / mol; and / or,

[0008] In the graft copolymer, the mass content of the polyoxazoline side chains is 1 to 50%; and / or,

[0009] The oxazoline monomer for preparing the polyoxazoline branch chain includes 2-methyl-2-oxazoline.

[0010] In one embodiment, the weight average molecular weight of the polyethersulfone main chain is 80,000 to 100,000 g / mol; and / or,

[0011] In the graft copolymer, the mass content of the polyoxazoline side chains is 10 to 50%; and / or,

[0012] The polyethersulfone has the following structural units:

[0013] .

[0014] In one embodiment, the preparation method of the graft copolymer comprises the following steps:

[0015] A -CH2X group is introduced into the benzene ring of polyethersulfone through reaction to obtain a polyethersulfone initiator;

[0016] The graft copolymer is prepared by performing a ring-opening polymerization reaction of the oxazoline monomer using the polyethersulfone initiator;

[0017] Wherein, X is a halogen atom.

[0018] In one embodiment, the preparation process of the polyethersulfone comprises:

[0019] The reaction mixture is reacted at 140-200° C. for 2-8 hours, and then the reaction system is reacted at 160-230° C. for 2-48 hours; wherein the reaction mixture comprises a first monomer, a second monomer and a salt-forming agent; and / or,

[0020] The preparation process of the polyethersulfone initiator comprises: mixing the polyethersulfone with paraformaldehyde, SnCl4 and (CH3)3SiCl and reacting at 30-60°C for 12-72h; and / or,

[0021] The process of the ring-opening polymerization reaction comprises:

[0022] The polyethersulfone initiator and the oxazoline monomer are reacted at 90-110° C. to obtain the graft copolymer.

[0023] In one embodiment, the molar number of -CH2X groups accounts for 5 to 50% of the total molar number of the polyethersulfone structural units; and / or,

[0024] X is a chlorine atom or a bromine atom; and / or,

[0025] The salt-forming agent includes one or more of sodium hydroxide, potassium hydroxide, cesium hydroxide, potassium carbonate, sodium carbonate, cesium carbonate, potassium bicarbonate, and sodium bicarbonate; and / or,

[0026] The first monomer includes bisphenol S, and the second monomer includes one or more of dichlorodiphenyl sulfone and difluorodiphenyl sulfone.

[0027] In a second aspect, the present invention provides a cooker comprising the above-mentioned Teflon composite coating.

[0028] In a third aspect, the present invention provides a graft copolymer of polyethersulfone and polyoxazoline, comprising a polyethersulfone main chain and polyoxazoline side chains grafted onto the polyethersulfone main chain.

[0029] In a fourth aspect, the present invention provides the use of the above-mentioned graft copolymer of polyethersulfone and polyoxazoline in the preparation of Teflon composite coatings or cookware.

[0030] The Teflon coating of the present invention has good metal adhesion and low yellowness coefficient. When used on cookware, the durability and aesthetics of the coating or cookware can be improved. DETAILED DESCRIPTION

[0031] Typical embodiments that embody the features and advantages of the present invention will be described in detail in the following description. It should be understood that the present invention is capable of various variations in different embodiments without departing from the scope of the present invention, and the descriptions herein are intended to be illustrative rather than limiting.

[0032] One embodiment of the present invention provides a graft copolymer of polyethersulfone and polyoxazoline (polyethersulfone- g -polyoxazoline), including a main chain and one or more side chains grafted to the main chain, the main chain is polyethersulfone (i.e., polyethersulfone main chain), and the side chains are polyoxazoline segments (i.e., polyoxazoline side chains).

[0033] In one embodiment, polyethersulfone is a resin comprising a sulfone group (-SO2-) and an arylene group in the main chain of the molecule.

[0034] In one embodiment, the polyethersulfone has the following structural units:

[0035]

[0036] In one embodiment, the weight average molecular weight of the polyethersulfone main chain can be 50,000 to 120,000 g / mol, further can be 60,000 to 100,000 g / mol, and further can be 70,000 to 100,000 g / mol, for example, 60,000 g / mol, 70,000 g / mol, 71,000 g / mol, 72,000 g / mol, 75,000 g / mol, 80,000 g / mol, 85,000 g / mol, 90,000 g / mol, 92,000 g / mol, 93,000 g / mol, 94,000 g / mol, 95,000 g / mol, 105,000 g / mol, and 110,000 g / mol.

[0037] In one embodiment, in the graft copolymer of polyethersulfone and polyoxazoline, the mass content of polyoxazoline side chains can be 1 to 50%, further can be 10 to 50%, further can be 35 to 50%, for example 2%, 6%, 8%, 10%, 10.5%, 11%, 12%, 15%, 18%, 25%, 30%, 35%, 40%, 45%.Wherein, the content of polyoxazoline side chains in the graft copolymer can be regulated by controlling the mol ratio of oxazoline monomer and polyethersulfone.

[0038] In one embodiment, the monomers used to prepare the polyethersulfone (main chain) include a first monomer and a second monomer. The first monomer includes bisphenol S, and the second monomer includes one or more of dichlorodiphenyl sulfone (e.g., 4,4'-dichlorodiphenyl sulfone) and difluorodiphenyl sulfone (e.g., 4,4'-difluorodiphenyl sulfone). Furthermore, the polyethersulfone can be prepared by a nucleophilic substitution reaction of the monomers.

[0039] In one embodiment, the oxazoline monomer used to prepare the polyoxazoline branches includes 2-methyl-2-oxazoline.

[0040] In one embodiment, the preparation process of the graft copolymer of polyethersulfone and polyoxazoline includes: first preparing polyethersulfone, then introducing a -CH2X group on the benzene ring of polyethersulfone by reaction to obtain a polyethersulfone initiator; then initiating the ring-opening polymerization of the oxazoline monomer through the -CH2X group in a grafting manner, for example, it can be a cationic ring-opening polymerization.

[0041] In one embodiment, X in the -CH2X group (benzyl halide) on the phenyl ring of the polyethersulfone initiator is a halogen atom, such as chlorine or bromine.

[0042] In one embodiment, the molar number of -CH2X groups on the phenyl ring of the polyethersulfone initiator accounts for 5-50% of the total moles of the polyethersulfone structural units (or repeating units), for example, 5%, 10%, 13%, 14%, 15%, 16%, 17%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%.

[0043] One embodiment of the present invention provides a method for preparing the above-mentioned graft copolymer of polyethersulfone and polyoxazoline, comprising the following steps:

[0044] A -CH2X group is introduced into the benzene ring of polyethersulfone through reaction to obtain a polyethersulfone initiator;

[0045] The graft copolymer was prepared by ring-opening polymerization of oxazoline monomer using polyethersulfone initiator.

[0046] Wherein, X is a halogen atom (eg, a chlorine atom).

[0047] In one embodiment, polyethersulfone can be prepared by reacting a first monomer and a second monomer. Further, the preparation process of polyethersulfone includes:

[0048] The reaction mixture is reacted at 140-200° C. (first reaction temperature) for 2-8 hours, and then the reaction system is reacted at 160-230° C. (second reaction temperature) for 2-48 hours; wherein the reaction mixture includes a first monomer, a second monomer and a salt-forming agent.

[0049] In one embodiment, the weight average molecular weight of the polyethersulfone is the same as the molecular weight of the polyethersulfone backbone, and the molecular weight distribution of the polyethersulfone is 1.50 to 2.50, for example, 1.50, 1.60, 1.65, 1.67, 1.70, 1.71, 1.80, 1.90, 2.00, 2.10, 2.20, 2.30, 2.40, and 2.50.

[0050] In one embodiment, the ratio of the amount of the first monomer to the amount of the second monomer can be 1:1.0 to 1:1.03; the amount of the salt-forming agent can be 1.05 to 1.3 times the amount of the first monomer, for example, 1.1 times, 1.15 times, 1.2 times, or 1.25 times.

[0051] In one embodiment, the reaction mixture for preparing the polyethersulfone containing an initiating group includes a first monomer, a second monomer, a salt-forming agent, and an organic solvent, and the organic solvent may include a first organic solvent.

[0052] In one embodiment, the organic solvent used in the preparation process of polyethersulfone includes a first organic solvent and a second organic solvent; the preparation process of polyethersulfone may include the following steps:

[0053] mixing the first monomer, the second monomer, the salt-forming agent, the first organic solvent, and the second organic solvent to obtain a reaction mixture; and

[0054] The reaction mixture is refluxed at 140-200° C. for 2-8 hours, the second organic solvent is evaporated, and the reaction system is reacted at 160-230° C. for 2-48 hours.

[0055] In one embodiment, the first monomer, the second monomer, and the salt-forming agent may be immersed in a first organic solvent in sequence, and then the second organic solvent is added to the system under stirring.

[0056] In one embodiment, the amount of the first organic solvent used is such that the solid content of the reaction system reaches 20 to 45 wt% (e.g., 25 wt%, 30 wt%, 35 wt%, 40 wt%), and the amount of the second solvent used is 0 to 20 wt% (e.g., 1 wt%, 2 wt%, 5 wt%, 10 wt%, 15 wt%) of the amount of the first solvent used.

[0057] In one embodiment, during the preparation of polyethersulfone, the first reaction temperature can be, for example, 150°C, 160°C, 170°C, 180°C, or 190°C, and the reaction time of the system at the first reaction temperature can be, for example, 3h, 4h, 5h, 6h, or 7h.

[0058] In one embodiment, during the preparation of polyethersulfone, the second reaction temperature can be, for example, 170°C, 180°C, 190°C, 200°C, 210°C, or 220°C, and the reaction time of the system at the second reaction temperature can be, for example, 3h, 3.5h, 4h, 5h, 6h, 8h, 10h, 12h, 15h, 20h, 25h, 30h, 35h, 40h, or 45h.

[0059] In one embodiment, during the preparation of polyethersulfone, after the reaction at the first reaction temperature is completed, the second organic solvent in the reaction system can be evaporated by increasing the system temperature.

[0060] In one embodiment, during the preparation of polyethersulfone, after the reaction at the second reaction temperature is completed, a capping agent is added to the system, followed by post-treatment. The post-treatment may include filtering the reaction fluid, crushing, washing with water, and vacuum drying.

[0061] In one embodiment, the first monomer may be bisphenol S, the second monomer may be one or more of dichlorodiphenyl sulfone (eg, 4,4'-dichlorodiphenyl sulfone) and difluorodiphenyl sulfone (eg, 4,4'-difluorodiphenyl sulfone), and the oxazoline monomer may be 2-methyl-2-oxazoline.

[0062] In one embodiment, the salt-forming agent may include one or more of sodium hydroxide, potassium hydroxide, cesium hydroxide, potassium carbonate, sodium carbonate, cesium carbonate, potassium bicarbonate, and sodium bicarbonate. Further, the salt-forming agent may be potassium carbonate and / or sodium carbonate.

[0063] In one embodiment, the first organic solvent may include dimethyl sulfoxide, dimethyl sulfone, N , N -dimethylformamide, N , N -dimethylacetamide, N - one or more of methyl pyrrolidone and sulfolane.

[0064] In one embodiment, the second organic solvent may include one or more of toluene, xylene, o-xylene, and chlorobenzene.

[0065] In one embodiment, the end-capping agent may include one or more of methyl chloride, ethyl chloride, and 4-chlorodiphenyl sulfone. Further, the end-capping agent may be methyl chloride.

[0066] In one embodiment, the preparation process of the polyethersulfone initiator includes: mixing polyethersulfone with paraformaldehyde, SnCl4 and (CH3)3SiCl and reacting at 30-60°C for 12-72 hours. Furthermore, the reaction temperature can be, for example, 35°C, 40°C, 45°C, 50°C or 55°C; and the reaction time can be, for example, 15 hours, 20 hours, 25 hours, 30 hours, 35 hours, 40 hours, 45 hours, 50 hours, 55 hours, 60 hours, 65 hours or 70 hours.

[0067] In one embodiment, the mass ratio of polyethersulfone to paraformaldehyde, SnCl4, and (CH3)3SiCl can be 100:30-40:2-4:100-140.

[0068] In one embodiment, the preparation process of the polyethersulfone initiator includes: dissolving polyethersulfone in a third organic solvent, adding paraformaldehyde, SnCl4 and (CH3)3SiCl to the formed solution, and reacting at 30-60°C for 12-72 hours; precipitating the reaction mixture in methanol, then filtering and separating the polymer, then dissolving the obtained polymer in a fourth organic solvent, and reprecipitating it with a fifth organic solvent, and then filtering and drying under vacuum conditions.

[0069] In one embodiment, the third organic solvent may be one or more of chloroform (trichloromethane), dichloromethane, and tetrahydrofuran; the fourth organic solvent may be one or more of chloroform (trichloromethane), dichloromethane, and tetrahydrofuran; and the fifth organic solvent may be methanol and / or ethanol.

[0070] In one embodiment, the molar number of -CH2X groups on the benzene ring of the polyethersulfone initiator accounts for 5-50% of the total molar number of the polyethersulfone structural unit (or repeating unit), and the value of the molar content can be adjusted by the feed ratio, reaction time, etc.

[0071] In one embodiment, the ring-opening polymerization process of the oxazoline monomer includes: reacting a polyethersulfone initiator and the oxazoline monomer at 90-110° C. to obtain a graft copolymer.

[0072] In one embodiment, the ring-opening polymerization reaction temperature of the oxazoline monomer can be 92°C, 95°C, 98°C, 100°C, 102°C, 105°C, 108°C; and the time can be 0.5 to 6 hours, for example, 0.5h, 1h, 2h, 3h, 4h, 5h, 6h.

[0073] In one embodiment, the ring-opening polymerization reaction of the oxazoline monomer may be carried out in a nitrogen atmosphere.

[0074] In one embodiment, the oxazoline monomer can be 2-methyl-2-oxazoline. Further, the graft density of the graft copolymer can be adjusted by controlling the amount of oxazoline monomer added and the conversion rate. For example, by extending the reaction time, the conversion rate can be increased to 100%. After the polymerization is completed, the system will completely change from liquid to solid.

[0075] In one embodiment, the amount of the oxazoline monomer used may be 1 to 50% of the mass of the polyethersulfone, such as 1%, 5%, 10%, 20%, 30%, 40%, or 50%.

[0076] One embodiment of the present invention provides a Teflon composite coating, comprising a surface layer and a bottom layer, wherein the surface layer comprises polytetrafluoroethylene, and the bottom layer comprises the above-mentioned graft copolymer of polyethersulfone and polyoxazoline.

[0077] In one embodiment, the graft copolymer of polyethersulfone and polyoxazoline comprises a polyethersulfone main chain and polyoxazoline side chains grafted onto the polyethersulfone main chain.

[0078] In one embodiment, the Teflon composite coating is disposed on the surface of the cookware through a base layer.

[0079] In one embodiment, the preparation method of the graft copolymer film (or layer) of polyethersulfone and polyoxazoline comprises the following steps:

[0080] 15-35 parts by mass of a graft copolymer of polyethersulfone and polyoxazoline, 35-55 parts by mass of water and 10-50 parts by mass of a sixth organic solvent are mixed to form a dispersion; the dispersion is dried at a temperature of 200-380° C. to form a film.

[0081] In one embodiment, the sixth organic solvent may be one or more of chloroform, N-methylpyrrolidone, N,N-dimethylformamide, and N,N-dimethylacetamide.

[0082] In one embodiment, the thickness of the graft copolymer membrane of polyethersulfone and polyoxazoline may be 10 to 2000 μm, for example, 50 μm, 100 μm, 200 μm, 500 μm, 800 μm, 1000 μm, 1200 μm, 1500 μm, or 1800 μm.

[0083] In one embodiment, the yellowness index of the graft copolymer film of polyethersulfone and polyoxazoline is less than 10, and may further be 4-5.

[0084] One embodiment of the present invention provides a cooker comprising the aforementioned Teflon composite coating or the aforementioned graft copolymer of polyethersulfone and polyoxazoline.

[0085] In one embodiment, the cookware is a utensil for cooking (such as a non-stick pan), and the Teflon composite coating is at least provided on the inner surface of the cookware.

[0086] One embodiment of the present invention provides the use of the above-mentioned graft copolymer of polyethersulfone and polyoxazoline (or the graft copolymer membrane of polyethersulfone and polyoxazoline) in the preparation of a Teflon composite coating.

[0087] The graft copolymer of polyethersulfone and polyoxazoline in one embodiment of the present invention is an amphiphilic copolymer comprising a hydrophobic polyethersulfone main chain and a hydrophilic polyoxazoline side chain, which can be well dissolved in polar organic solvents and has good film-forming properties.

[0088] The graft copolymer membrane of polyethersulfone and polyoxazoline according to one embodiment of the present invention has better metal adhesion and lower yellowness index compared to the polyethersulfone membrane.

[0089] A graft copolymer of polyethersulfone and polyoxazoline, according to one embodiment of the present invention, exhibits good compatibility with polytetrafluoroethylene, a low yellowness index, and excellent water dispersibility. Furthermore, the graft copolymer of polyethersulfone and polyoxazoline has a stable structure. Its application in Teflon coatings can effectively improve adhesion between the coating and the substrate (e.g., metal), reducing the risk of coating detachment.

[0090] In a Teflon coating according to one embodiment of the present invention, the presence of polyoxazoline improves the yellowing resistance of the coating, so that the coating can still maintain its original color after long-term use.

[0091] One embodiment of the present invention utilizes a two-layer Teflon coating, simplifying the spraying process compared to existing three-layer coatings. It also exhibits improved adhesion and a low yellowness index, enhancing the coating's durability and aesthetics. These features address existing issues such as the complex three-layer spraying process, the tendency for the coating to fall off the substrate over time, yellowing, and the poor hydrophilicity of polyethersulfone.

[0092] The preparation and application of the graft copolymer of polyethersulfone and polyoxazoline according to one embodiment of the present invention are further described below with reference to the following examples.

[0093] raw material

[0094] Bisphenol S was purchased from Jiangsu Aolunda Technology Industry Co., Ltd.; dichlorodiphenyl sulfone was purchased from Hebei Jianxin Chemical Co., Ltd.; and salt-forming agent was purchased from Haihua Group.

[0095] Test Method

[0096] 1. Weight average molecular weight and molecular weight distribution

[0097] The molecular weight of polyethersulfone was determined by gel permeation chromatography (GPC) using DMF containing 20 mmol lithium bromide as the mobile phase, PMMA as the standard sample, and Agilent MIXD C, MIXD D, and MIXD E columns connected in series at a flow rate of 1.0 mL / min.

[0098] 2. Adhesion test to metal

[0099] Polyethersulfone- g -The dispersion of polyoxazoline was sprayed on the cleaned metal surface to form a coating, and the adhesion between the coating and the metal was tested according to the ASTM D3359 cross-sectional test method.

[0100] 3. Yellowness test

[0101] The yellowness index was tested according to ASTM E313 (2 mm).

[0102] Example 1

[0103] Preparation of polyethersulfone

[0104] 1001.1g of bisphenol S, 1159.9g of 4,4'-dichlorodiphenyl sulfone and 635.7g of potassium carbonate were added to 3446.8g of cyclopentane in sequence, and then 1723.3g of xylene was added to the reactor under stirring. The mixture was heated to 160°C (first reaction temperature) and refluxed for 5h. When no water was produced, the temperature was increased to completely evaporate the xylene in the reactor. The mixture was then reacted at 220°C (second reaction temperature) for 3.5h. Methyl chloride was then introduced for a 30min end-capping reaction. Finally, the obtained reaction liquid was filtered, crushed, washed with water and vacuum dried to obtain polyethersulfone.

[0105] Preparation of polyethersulfone initiator

[0106] 100 g of the polyethersulfone prepared above was dissolved in 2.5 L of chloroform, and 33.6 g of paraformaldehyde, 2.94 g of SnCl4, and 142.8 mL of (CH3)3SiCl were added to the completely dissolved solution. The mixture was then reacted at 40°C for 72 hours. The resulting reaction mixture was precipitated in methanol, and the polymer was separated by filtration. The polymer was then dissolved in 2.5 L of chloroform and reprecipitated in methanol, filtered, and dried under vacuum for 24 hours to obtain a polyethersulfone initiator. The molar number of -CH2X groups on the benzene ring of the polyethersulfone initiator accounted for 15% of the total molar number of the polyethersulfone structural units.

[0107] Polyethersulfone- g Preparation of polyoxazoline graft copolymers

[0108] Under nitrogen atmosphere, 50 g of the polyethersulfone initiator prepared above was added to a reaction bottle, and the resulting mixture was mixed with 6 mL of 2-methyl-2-oxazoline monomer. The system was then heated to 100 ° C. to initiate bulk polymerization of the oxazoline monomer. After reacting for 2 h, the polymerization was terminated with 2 mL of NaOH aqueous solution (0.2 mol / L). The reaction material was vacuum dried to constant weight to obtain a graft copolymer of polyethersulfone and polyoxazoline (PES- g -PMOX), whose structural formula is as follows:

[0109]

[0110] The polyethersulfone prepared according to the aforementioned method was tested, and its weight average molecular weight was 91540 g / mol, and the molecular weight distribution was 1.70; the mass content of poly(2-methyl-2-oxazoline) side chains was calculated to be 10.6%.

[0111] Polyethersulfone- g -Preparation of polyoxazoline membrane

[0112] 30 parts by mass of the polyethersulfone prepared above g-Polyoxazoline powder, 35 parts by mass of water, and 35 parts by mass of N-methylpyrrolidone were mixed and stirred to form polyethersulfone- g -polyoxazoline dispersion, the dispersion is dried at a high temperature of 350°C to form a film with a thickness of 200 μm.

[0113] According to the above method, polyethersulfone- g -Polyoxazoline dispersion was sprayed on the metal surface for adhesion test. The results showed that the adhesion between the film and the metal met the requirements of ASTM grade 5B‌. g -The polyoxazoline film was tested for yellowness, and the yellowness index was 5.

[0114] Heat polytetrafluoroethylene to a molten state, add the polyethersulfone- g -poly (2-methyl-2-oxazoline) powder was stirred, and the polyethersulfone powder could adhere to the surface of polytetrafluoroethylene without stratification, indicating that polytetrafluoroethylene and polyethersulfone- g -Poly (2-methyl-2-oxazoline) has better adhesion.

[0115] Example 2

[0116] This example uses the same raw materials and process as Example 1 to prepare polyethersulfone- g -polyoxazoline and its membrane, the only difference is that: in the preparation of polyethersulfone, N-methylpyrrolidone is used instead of cyclopentane, and xylene is not added; the second reaction temperature is 200°C, and the reaction time is 5h.

[0117] The polyethersulfone prepared according to the aforementioned method was tested, and its weight average molecular weight was 90980 g / mol, and the molecular weight distribution was 1.71; the mass content of poly(2-methyl-2-oxazoline) side chains was calculated to be 10.6%.

[0118] The same method as in Example 1 was used to prepare polyethersulfone- g - Adhesion test of polyoxazoline to metal shows that it meets ASTM Grade 5B requirements.

[0119] The same method as in Example 1 was used to prepare polyethersulfone- g - Yellowness test of polyoxazoline film, yellowness index is 5.

[0120] The same method as in Example 1 was used to prepare polyethersulfone- g - Adhesion Test of Poly(2-methyl-2-oxazoline) to Polytetrafluoroethylene, Polyethersulfone- g -Poly (2-methyl-2-oxazoline) can adhere to the surface of polytetrafluoroethylene without delamination, indicating that the two have good adhesion.

[0121] Example 3

[0122] This example uses the same raw materials and process as Example 1 to prepare polyethersulfone- g -polyoxazoline and its membrane, the only difference being that 10 mL of 2-methyl-2-oxazoline monomer was added during the preparation of the graft copolymer.

[0123] The polyethersulfone prepared according to the aforementioned method was tested, and its weight average molecular weight was 91965 g / mol, and the molecular weight distribution was 1.73; the mass content of poly(2-methyl-2-oxazoline) branches was calculated to be 16.5%.

[0124] The same method as in Example 1 was used to prepare polyethersulfone- g - Adhesion test of polyoxazoline to metal shows that it meets ASTM Grade 5B requirements.

[0125] The same method as in Example 1 was used to prepare polyethersulfone- g - Yellowness test of polyoxazoline film, yellowness index is 5.

[0126] The same method as in Example 1 was used to prepare polyethersulfone- g - Adhesion Test of Poly(2-methyl-2-oxazoline) to Polytetrafluoroethylene, Polyethersulfone- g -Poly (2-methyl-2-oxazoline) can adhere to the surface of polytetrafluoroethylene without delamination, indicating that the two have good adhesion.

[0127] Example 4

[0128] This example uses the same raw materials and process as Example 1 to prepare polyethersulfone- g -polyoxazoline and its membrane, the only difference being that 30 mL of 2-methyl-2-oxazoline monomer was added during the preparation of the graft copolymer.

[0129] The polyethersulfone prepared according to the aforementioned method was tested, and its weight average molecular weight was 92080 g / mol, and the molecular weight distribution was 1.68; the mass content of poly(2-methyl-2-oxazoline) side chains was calculated to be 37.2%.

[0130] The same method as in Example 1 was used to prepare polyethersulfone- g - Adhesion test of polyoxazoline to metal shows that it meets ASTM Grade 5B requirements.

[0131] The same method as in Example 1 was used to prepare polyethersulfone- g - Yellowness test of polyoxazoline film, yellowness index is 4.

[0132] The same method as in Example 1 was used to prepare polyethersulfone- g- Adhesion Test of Poly(2-methyl-2-oxazoline) to Polytetrafluoroethylene, Polyethersulfone- g -Poly (2-methyl-2-oxazoline) can adhere to the surface of polytetrafluoroethylene without delamination, indicating that the two have good adhesion.

[0133] Example 5

[0134] This example uses the same raw materials and process as Example 1 to prepare polyethersulfone- g -polyoxazoline and its membrane, the only difference being that 45 mL of 2-methyl-2-oxazoline monomer was added during the preparation of the graft copolymer.

[0135] The polyethersulfone prepared according to the aforementioned method was tested, and its weight average molecular weight was 91055 g / mol, and the molecular weight distribution was 1.69; the mass content of poly(2-methyl-2-oxazoline) side chains was calculated to be 47.0%.

[0136] The same method as in Example 1 was used to prepare polyethersulfone- g - Adhesion test of polyoxazoline to metal shows that it meets ASTM Grade 5B requirements.

[0137] The same method as in Example 1 was used to prepare polyethersulfone- g - Yellowness test of polyoxazoline film, yellowness index is 4.

[0138] The same method as in Example 1 was used to prepare polyethersulfone- g - Adhesion Test of Poly(2-methyl-2-oxazoline) to Polytetrafluoroethylene, Polyethersulfone- g -Poly (2-methyl-2-oxazoline) can adhere to the surface of polytetrafluoroethylene without delamination, indicating that the two have good adhesion.

[0139] Example 6

[0140] This example uses the same raw materials and process as Example 1 to prepare polyethersulfone- g - polyoxazoline and its membrane, the only difference being that in the preparation of polyethersulfone, the second reaction time is 3 h.

[0141] The polyethersulfone prepared according to the aforementioned method was tested, and its weight average molecular weight was 71850 g / mol, and the molecular weight distribution was 1.67; the mass content of poly(2-methyl-2-oxazoline) side chains was calculated to be 10.6%.

[0142] The same method as in Example 1 was used to prepare polyethersulfone- g - Adhesion test of polyoxazoline to metal shows that it meets ASTM Grade 5B requirements.

[0143] The same method as in Example 1 was used to prepare polyethersulfone- g - Yellowness test of polyoxazoline film, yellowness index is 4.

[0144] The same method as in Example 1 was used to prepare polyethersulfone- g - Adhesion Test of Poly(2-methyl-2-oxazoline) to Polytetrafluoroethylene, Polyethersulfone- g -Poly (2-methyl-2-oxazoline) can adhere to the surface of polytetrafluoroethylene without delamination, indicating that the two have good adhesion.

[0145] Comparative Example 1

[0146] Preparation of polyethersulfone membrane

[0147] 30 parts by mass of the polyethersulfone powder prepared in Example 1, 35 parts by mass of water and 35 parts by mass of N-methylpyrrolidone were mixed and stirred to form a polyethersulfone dispersion. The dispersion was dried at a high temperature of 350° C. to form a film with a thickness of 200 μm.

[0148] The polyethersulfone dispersion was tested for adhesion according to the aforementioned method, and the results showed that it met the requirements of ASTM Grade 3B. The polyethersulfone was also tested for yellowness according to the aforementioned method, and the yellowness index was 16.

[0149] When polytetrafluoroethylene is heated to a molten state and polyethersulfone powder is added and stirred, the polyethersulfone powder cannot adhere to the surface of polytetrafluoroethylene, and the two are separated into layers, indicating that the adhesion between polytetrafluoroethylene and polyethersulfone is poor.

[0150] Table 1 lists the differences and performance parameters of the polymer films of various embodiments and Comparative Example 1.

[0151] Table 1 Structural parameters and performance parameters of the polymer films of each embodiment and comparative example 1

[0152]

[0153] According to the results of Example 1 and Comparative Example 1 in Table 1, compared with Comparative Example 1, the embodiment of the present invention uses a graft copolymer of polyethersulfone and polyoxazoline as the bottom layer of the Teflon composite coating, which can make the coating have better adhesion and low yellowness coefficient, thereby improving the durability and aesthetics of the coating.

[0154] Unless otherwise defined, the terms used in the present invention have the same meanings as those commonly understood by those skilled in the art.

[0155] The embodiments described in the present invention are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. Those skilled in the art may make various other substitutions, changes and improvements within the scope of the present invention. Therefore, the present invention is not limited to the above-mentioned embodiments, but is only limited by the claims.

Claims

1. A cooker comprising a Teflon composite coating, characterized in that: The Teflon composite coating comprises a surface layer and a bottom layer, wherein the surface layer comprises polytetrafluoroethylene, and the bottom layer comprises a graft copolymer of polyethersulfone and polyoxazoline; and the preparation method of the graft copolymer comprises the following steps: A -CH2X group is introduced into the benzene ring of polyethersulfone through reaction to obtain a polyethersulfone initiator; The graft copolymer is prepared by performing a ring-opening polymerization reaction of the oxazoline monomer using the polyethersulfone initiator; Wherein, X is a halogen atom.

2. The cooker according to claim 1, characterized in that The graft copolymer includes a polyethersulfone main chain and a polyoxazoline side chain grafted to the polyethersulfone main chain.

3. The cooker according to claim 2, characterized in that The weight average molecular weight of the polyethersulfone main chain is 50,000 to 120,000 g / mol; and / or, In the graft copolymer, the mass content of the polyoxazoline side chains is 1 to 50%; and / or, The oxazoline monomer for preparing the polyoxazoline branch chain includes 2-methyl-2-oxazoline.

4. The cooker according to claim 2, wherein: The weight average molecular weight of the polyethersulfone main chain is 80,000 to 100,000 g / mol; and / or, In the graft copolymer, the mass content of the polyoxazoline side chains is 10 to 50%; and / or, The polyethersulfone has the following structural units: 。 5. The cooker according to claim 1, characterized in that The preparation process of the polyethersulfone comprises: The reaction mixture is reacted at 140-200° C. for 2-8 hours, and then the reaction system is reacted at 160-230° C. for 2-48 hours; wherein the reaction mixture comprises a first monomer, a second monomer and a salt-forming agent; and / or, The preparation process of the polyethersulfone initiator comprises: mixing the polyethersulfone with paraformaldehyde, SnCl4 and (CH3)3SiCl and reacting at 30-60°C for 12-72h; and / or, The process of the ring-opening polymerization reaction comprises: The polyethersulfone initiator and the oxazoline monomer are reacted at 90-110° C. to obtain the graft copolymer.

6. The cooker according to claim 5, characterized in that The molar number of -CH2X groups accounts for 5 to 50% of the total molar number of the polyethersulfone structural unit; and / or, X is a chlorine atom or a bromine atom; and / or, The salt-forming agent includes one or more of sodium hydroxide, potassium hydroxide, cesium hydroxide, potassium carbonate, sodium carbonate, cesium carbonate, potassium bicarbonate, and sodium bicarbonate; and / or, The first monomer includes bisphenol S, and the second monomer includes one or more of dichlorodiphenyl sulfone and difluorodiphenyl sulfone.

7. Use of a graft copolymer of polyethersulfone and polyoxazoline in preparing a Teflon composite coating for the cookware according to any one of claims 1 to 6.

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