Coating for metal protection and preparation method thereof

Abstract

The invention relates to the technical field of coatings, in particular to a coating for metal protection and a preparation method thereof. The coating is prepared from the following components in parts by weight: 25 to 35 parts of modified rosin-based resin, 15 to 25 parts of cyclohexanone, 5 to 10 parts of diethyl phthalate, 5 to 10 parts of borax, 1 to 5 parts of modified aluminum oxide, 1 to 5 parts of modified silicon oxide and 5 to 35 parts of auxiliaries.

Description

Technical Field

[0001] The present disclosure relates to the technical field of coatings, and in particular to a coating for metal protection and a preparation method thereof. Background Art

[0002] Metal materials are widely used in various fields such as construction, transportation, and national defense. However, metals are prone to chemical reactions with the surrounding environment during use, causing corrosion. Corrosion is an increasingly serious problem, resulting in a huge waste of resources worldwide each year. To address this problem, a coating for metal protection is urgently needed.

[0003] Rosin is a biomass resource obtained from pine trees through processes such as distillation. Epoxy resin is widely used in industrial fields and high-tech industries such as aerospace, new energy vehicles, wind power generation, 5G communications, and marine corrosion protection. In recent years, its usage in my country has been huge and has increased year by year. Therefore, rosin-based epoxy resin can be considered for use in coatings for the protection of metal materials. Summary of the Invention

[0004] The present disclosure provides a coating for metal protection and a preparation method thereof to address the deficiencies in the related art.

[0005] According to a first aspect of an embodiment of the present disclosure, there is provided a coating for metal protection, the coating comprising the following components in parts by weight: 25-35 parts by weight of modified rosin-based resin, 15-25 parts by weight of cyclohexanone, 5-10 parts by weight of diethyl phthalate, 5-10 parts by weight of borax, 1-5 parts by weight of modified alumina, 1-5 parts by weight of modified silicon oxide and 5-35 parts by weight of auxiliary agents.

[0006] In one aspect of the embodiments of the present disclosure, preferably, the coating comprises the following components in parts by weight: 28-32 parts by weight of modified rosin-based resin, 20-25 parts by weight of cyclohexanone, 8-10 parts by weight of diethyl phthalate, 5-7 parts by weight of borax, 2-4 parts by weight of modified alumina, 2-4 parts by weight of modified silica and 10-15 parts by weight of auxiliary agents.

[0007] In one aspect of the embodiments of the present disclosure, the modified alumina is alumina nanoparticles that have been oleophilically modified; the oleophilic modification process comprises the following steps: Step 1-a: providing aluminum oxide nanoparticles, and dispersing the aluminum oxide nanoparticles in anhydrous ethanol; Step 2-a: adding hexadecyltrimethoxysilane, water, and glacial acetic acid to the anhydrous ethanol in sequence, and stirring at room temperature for 2-3 hours to obtain a first mixed solution; Step 3-a: Add E51 epoxy resin solution and acetone to the first mixed solution and stir for 0.5-1 hour to obtain a second mixed solution; Step 4-a: spraying the second mixed solution onto a substrate, and then letting it stand for 2-3 hours, collecting the product, washing it, and drying it to obtain the oleophilically modified aluminum oxide nanoparticles.

[0008] In one aspect of the embodiments of the present disclosure, the modified silicon oxide is silicon oxide nanoparticles that have been lipophilically modified; the lipophilic modification process comprises the following steps: Step 1-b: providing silicon oxide nanoparticles, and dispersing the silicon oxide nanoparticles in anhydrous ethanol; Step 2-b: adding aqueous ammonia to the anhydrous ethanol, maintaining stirring, adding trimethoxy(3-methoxypropyl)silane dropwise to the solution, then heating to 45°C-55°C, and continuing stirring for 2-3 hours to obtain a third mixed solution; Step 3-b: Cool the third mixed solution to room temperature, dissolve hexadecyl acrylate in anhydrous ethanol, add the solution to the third mixed solution, continue stirring for 1-2 hours, filter, wash, and dry to obtain the lipophilically modified silicon oxide nanoparticles.

[0009] In one aspect of the embodiments of the present disclosure, the modified rosin-based resin is prepared by the following steps: Step 1-c: Add rosin-based glycol diglycidyl acrylate and methylphenyldimethoxysilane to a reaction vessel, heat to 90°C-100°C, keep stirring, then add a catalyst, react for 4-5 hours, and then cool to 75°C-80°C; Step 2-c: Add formaldehyde and tung oil to the cooled reaction vessel, continue the reaction for 3-4 hours, then cool to 40°C-50°C and maintain the temperature for 6-12 hours, then collect the orange-red transparent viscous liquid at the bottom layer to obtain the modified rosin-based resin.

[0010] In one aspect of the embodiments of the present disclosure, the auxiliary agent comprises at least one of a defoaming agent, a dispersant, and a leveling agent.

[0011] In one aspect of the embodiments of the present disclosure, preferably, the auxiliary agent comprises a dispersant and a leveling agent.

[0012] In one aspect of the embodiments of the present disclosure, the defoaming agent is selected from tributyl phosphate, defoaming agent Deqian 3100 or defoaming agent BYK088.

[0013] In one aspect of the embodiments of the present disclosure, the dispersant is selected from polycarboxylate dispersant 5040 or sodium hexametaphosphate.

[0014] In one aspect of the embodiments of the present disclosure, the leveling agent is selected from leveling agent BYK-333 or silicone leveling agent HY-5030.

[0015] In one aspect of the disclosed embodiments, the coating further comprises 2-8 parts by weight of a compound D having the following structural formula:

[0016] wherein R1 and R2 are each independently selected from hydrogen, a halogen atom, a nitro group, an amino group, a cyano group, a hydroxyl group, a carboxyl group, a substituted or unsubstituted C1-C30 alkyl group, a substituted or unsubstituted C2-C30 alkenyl group, a substituted or unsubstituted C2-C30 alkynyl group, a substituted or unsubstituted C1-C30 alkoxy group, a substituted or unsubstituted C3-30 cycloalkyl group, a substituted or unsubstituted C6-C30 aryl group, a substituted or unsubstituted 3-30 membered heterocyclyl group, or a substituted or unsubstituted 5-30 membered heteroaryl group.

[0017] In one aspect of the embodiments of the present disclosure, preferably, R1 and R2 are each independently selected from hydrogen, a halogen atom, a nitro group, an amino group, a cyano group, a hydroxyl group, a carboxyl group, a C1-C10 alkyl group, a C2-C10 alkenyl group, a C3-12 cycloalkyl group or a C6-C12 aryl group.

[0018] In one aspect of the disclosed embodiments, the coating further comprises 2-8 parts by weight of compound D-1, wherein the compound D-1 has the following structural formula:

[0019] According to a second aspect of the embodiments of the present disclosure, there is provided a method for preparing the aforementioned coating for metal protection, the method comprising the following steps: Step 1-d: preparing a modified rosin-based resin; Step 2-d: mixing the modified rosin-based resin and diethyl phthalate with mechanical stirring; Step 3-d: preparing oleophilic modified aluminum oxide nanoparticles and oleophilic modified silicon oxide nanoparticles, adding borax, the prepared modified aluminum oxide, and the modified silicon oxide into cyclohexanone and fully dispersing them; Step 5-d: Prepare compound D-1 and mix it with an auxiliary agent; Step 6-d: slowly mix the product obtained in step 3-d and the product obtained in step 2-d, and then add the product obtained in step 5-d to obtain the coating for metal protection.

[0020] In one aspect of the embodiments of the present disclosure, step 5-d further includes the following steps: Step 1-e: using imidazole-2-carboxylic acid and 2-amino-2-(1H-imidazol-2-yl)ethan-1-ol hydrochloride as raw materials, condensing to obtain intermediate 1;

[0021] Step 2-e: reacting intermediate 1 with p-toluenesulfonyl chloride to obtain intermediate 2;

[0022] Step 3-e: reacting the intermediate product 2 with N,N-diisopropylethylamine to obtain compound D-1;

[0023] The technical solutions provided by the embodiments of the present disclosure may have the following beneficial effects: It can be seen from the above examples that the present disclosure prepares a coating for metal protection with excellent performance, which has good anti-corrosion effect.

[0024] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure. DETAILED DESCRIPTION

[0025] The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present disclosure. Instead, they are merely examples of devices and methods consistent with some aspects of the present disclosure as detailed in the appended claims.

[0026] To make the purpose, technical solutions, and advantages of this application more clear, the technical solutions of this application will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of this application, rather than all the embodiments. The relevant embodiments described herein are illustrative and are used to provide a basic understanding of this application. The embodiments of this application should not be interpreted as limiting this application.

[0027] For the sake of clarity, only some numerical ranges are specifically disclosed herein. However, any lower limit may be combined with any upper limit to form an unspecified range; and any lower limit may be combined with other lower limits to form an unspecified range, and similarly, any upper limit may be combined with any other upper limit to form an unspecified range. In addition, each individually disclosed point or single value may itself serve as a lower limit or upper limit and be combined with any other point or single value, or with other lower limits or upper limits, to form an unspecified range.

[0028] As used herein, the terms "comprises," "comprising," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not preclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0029] In the description herein, unless otherwise specified, “above” and “below” include the number itself.

[0030] Unless otherwise specified, the terms used in this disclosure have the commonly understood meanings commonly understood by those skilled in the art. Unless otherwise specified, the numerical values of the various parameters mentioned in this disclosure can be measured using various measurement methods commonly used in the art (for example, they can be tested according to the methods given in the examples of this disclosure).

[0031] The term "about" is used to describe and illustrate small changes. When used in conjunction with an event or situation, the term may refer to an example in which the event or situation occurs precisely and an example in which the event or situation occurs very approximately. For example, when used in conjunction with a numerical value, the term may refer to a variation range of less than or equal to ±10% of the numerical value, such as less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%. In addition, amounts, ratios, and other numerical values are sometimes presented in this article in a range format. It should be understood that such range formats are for convenience and brevity, and should be flexibly understood to include not only numerical values explicitly designated as range limits, but also all individual numerical values or subranges encompassed within the range, as if each numerical value and subrange were explicitly designated.

[0032] A list of items connected by the terms "at least one of," "at least one of," "at least one of," or other similar terms can mean any combination of the listed items. For example, if items A and B are listed, the phrase "at least one of A and B" means only A; only B; or A and B. In another example, if items A, B, and C are listed, the phrase "at least one of A, B, and C" means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C. Item A can contain a single component or multiple components. Item B can contain a single component or multiple components. Item C can contain a single component or multiple components.

[0033] In this disclosure, the term "alkyl" refers to an aliphatic hydrocarbon group, which can be straight or branched. Branched refers to one or more lower alkyl groups, such as methyl, ethyl, or propyl, attached to a linear alkyl chain. "Lower alkyl" refers to a group containing from about 1 to about 6 carbon atoms in the chain, which can be straight or branched.

[0034] In this disclosure, the term "alkenyl" refers to an aliphatic hydrocarbon group containing at least one carbon-carbon double bond, which can be straight or branched. Branched refers to one or more lower alkyl groups, such as methyl, ethyl, or propyl, attached to a linear alkenyl chain. "Lower alkenyl" refers to a group containing about 2 to about 6 carbon atoms in the chain, which can be straight or branched.

[0035] In this disclosure, the term "alkynyl" refers to an aliphatic hydrocarbon group containing at least one carbon-carbon triple bond, which can be straight or branched. Branched refers to one or more lower alkyl groups, such as methyl, ethyl, or propyl, attached to a linear alkynyl chain. "Lower alkynyl" refers to a group containing about 2 to about 6 carbon atoms in the chain, which can be straight or branched. Non-limiting examples of alkynyl include ethynyl, propynyl, 2-butynyl, 3-methylbutynyl, n-pentynyl, and decynyl.

[0036] In this disclosure, the term "aryl" refers to an aromatic monocyclic or polycyclic ring system. An aryl group may be optionally substituted with one or more "ring system substituents," which may be the same or different, and are as defined herein. Non-limiting examples of suitable aryl groups include phenyl and naphthyl.

[0037] In this disclosure, the term "heteroaryl" refers to an aromatic monocyclic or polycyclic ring system in which one or more of the ring atoms is an element other than carbon, such as nitrogen, oxygen or sulfur, alone or in combination. Preferred heteroaryls contain about 5 to about 6 ring atoms. The "heteroaryl" may be optionally substituted by one or more "ring system substituents," which may be the same or different, and are as defined herein. The prefix aza, oxa or thia before the heteroaryl root name means that at least a nitrogen, oxygen or sulfur atom, respectively, is present as a ring atom. A nitrogen atom of a heteroaryl may be optionally oxidized to the corresponding N-oxide. Non-limiting examples of suitable heteroaryl groups include pyridinyl, pyrazinyl, furanyl, thiophenyl, pyrimidinyl, isoxazolyl, isothiazolyl, oxazolyl, thiazolyl, pyrazolyl, furazanyl, pyrrolyl, pyrazolyl, triazolyl, 1,2,4-thiadiazolyl, pyrazinyl, pyridazinyl, quinoxalinyl, naphthyridinyl, imidazo[1,2-a]pyridinyl, imidazo[2,1-b]thiazolyl, benzofurazanyl, indolyl, azaindolyl, benzimidazolyl, benzothiophenyl, quinolinyl, imidazolyl, thienopyridinyl, quinazolinyl, thienopyrimidinyl, pyrrolopyridinyl, imidazopyridinyl, isoquinolinyl, benzazaindolyl, 1,2,4-triazinyl, benzothiazolyl, and the like.

[0038] In the present disclosure, the term "amino" refers to a -NR'R" group. The amino group may be optionally substituted. In an unsubstituted amino group, R' and R" are hydrogen. In a substituted amino group, R' and R" are each independently, but not limited to, hydrogen, alkyl, heteroalkyl, cycloalkyl, heterocycloalkyl, alkylcycloalkyl, alkylheterocycloalkyl, alkoxy, sulfonyl, alkenyl, alkanoyl, aryl, arylalkyl, or heteroaryl, provided that R' and R" are not both hydrogen. In a substituted amino group, R' and R" may be cyclized to form a cyclic amino group, such as a pyrrolidinyl or piperidinyl group. Such cyclic amino groups may incorporate other heteroatoms, for example, to form a piperazine or morpholine group. Such cyclic amino groups may be optionally substituted, for example, by an amino group, a hydroxyl group, or an oxo group.

[0039] In this disclosure, the term "alkoxy" refers to an -O-alkyl group. Alkoxy can refer to a linear, branched, or cyclic, saturated or unsaturated oxy-hydrocarbon chain, including, for example, methoxy, ethoxy, propoxy, isopropoxy, butoxy, tert-butoxy, and pentoxy. Alkoxy can optionally be substituted with one or more alkoxy substituents ("substituted alkoxy").

[0040] In the present disclosure, the term "cycloalkyl" refers to a non-aromatic mono- or polycyclic ring system, preferably a cycloalkyl ring containing about 5 to about 7 ring atoms. The cycloalkyl group may optionally be substituted with one or more "ring system substituents," which may be the same or different and are as defined above. Non-limiting examples of suitable monocyclic cycloalkyl groups include cyclopropyl, cyclopentyl, cyclohexyl, cycloheptyl, and the like. Non-limiting examples of suitable polycyclic cycloalkyl groups include 1-decalinyl, norbornyl, adamantyl, and the like. In the present disclosure, the term "cycloalkoxy" refers to a group in which one or more carbon atoms of the mono- or polycyclic ring system of a "cycloalkyl" group are replaced by oxygen atoms.

[0041] In this disclosure, the term "heterocyclyl" refers to a non-aromatic saturated monocyclic or polycyclic ring system in which one or more of the ring atoms is an element other than carbon, such as nitrogen, oxygen, or sulfur, either alone or in combination. There are no adjacent oxygen and / or sulfur atoms in the ring system. Preferred heterocycles contain about 5 to about 6 ring atoms. The prefix aza, oxa, or thia before the heterocyclyl root name means that at least a nitrogen, oxygen, or sulfur atom, respectively, is present as a ring atom. The heterocyclyl group may be optionally substituted by one or more "ring system substituents," which may be the same or different, and are defined herein. The nitrogen or sulfur atom of the heterocyclyl group may be optionally oxidized to the corresponding N-oxide, S-oxide, or S,S-dioxide. Non-limiting examples of suitable monocyclic heterocyclyl rings include piperidinyl, pyrrolidinyl, piperazinyl, morpholinyl, thiomorpholinyl, thiazolidinyl, 1,3-dioxolanyl, 1,4-dioxanyl, tetrahydrofuranyl, tetrahydrophenylthio, tetrahydrothiopyranyl, and the like.

[0042] The present disclosure is further illustrated below by way of specific examples. The various chemical reagents used in the examples of this disclosure were obtained through conventional commercial sources unless otherwise specified. Unless otherwise specified, the amounts described below are by weight. Unless otherwise specified, the results are understood to be at room temperature.

[0043] Example: Example 1: Example 1 includes the following steps: 1. Preparation of oleophilic-modified alumina nanoparticles: 25 g of commercially available alumina nanoparticles (D90 particle size of 100 nm) were provided and dispersed in 250 mL of anhydrous ethanol; 20 mL of hexadecyltrimethoxysilane, 40 mL of distilled water, and 10 mL of glacial acetic acid were sequentially added to the anhydrous ethanol, and the mixture was stirred at room temperature for 3 hours to obtain a first mixed solution; 25 mL of E51 epoxy resin solution and 50 mL of acetone were added to the first mixed solution, and the mixture was stirred for 1 hour to obtain a second mixed solution; the second mixed solution was sprayed onto a substrate (glass plate) at a distance of 60 cm between the spray gun and the glass plate surface and a spraying pressure of 0.3 MPa, and the mixture was allowed to stand for 3 hours. The product was then collected, washed, and dried to obtain oleophilic-modified alumina nanoparticles.

[0044] 2. Preparation of lipophilic-modified silica nanoparticles: 25 g of commercially available silica nanoparticles (D90 particle size of 2 μm) were provided, and the silica nanoparticles were dispersed in 250 mL of anhydrous ethanol. 15 g of aqueous ammonia was added to the anhydrous ethanol while stirring. 25 g of trimethoxy(3-methoxypropyl)silane was placed in a constant pressure funnel and added dropwise to the solution within 1 h. The temperature was then raised to 50° C. and stirred for 2 h to obtain a third mixed solution. The third mixed solution was then cooled to room temperature, 20 g of hexadecyl acrylate was dissolved in anhydrous ethanol and added to the third mixed solution. The mixture was stirred for 2 h, and the lipophilic-modified silica nanoparticles were obtained by filtration, washing, and drying.

[0045] 3. Preparation of modified rosin-based resin: 40 g of rosin-based ethylene glycol diglycidyl acrylate (rosin-based ethylene glycol diglycidyl acrylate is prepared by the following steps: adding rosin acrylate and triethylamine to a four-necked flask equipped with a stirrer, a condenser, a dropping funnel, and a nitrogen conduit, heating to melt the rosin acrylate, adding butanediol diglycidyl ether dropwise, and reacting for 2 h) and 15 g of methylphenyldimethoxysilane are added to a reaction vessel, heated to 90°C, stirred, and then 0.2 g of tetraisopropyl titanate catalyst is added. After reacting for 4 h, the temperature is lowered to 80°C; 5 g of formaldehyde and 7.5 g of tung oil are added to the cooled reaction vessel, the reaction is continued for 4 h, and then the temperature is lowered to 50°C and maintained at this temperature for 10 h. The orange-red transparent viscous liquid in the lower layer is collected to obtain a modified rosin-based resin.

[0046] 4. Preparation of Compound D-1: Dissolve 30 mmol of imidazole-2-carboxylic acid in an appropriate amount of DMF and transfer to a single-necked flask. Add 45 mmol of HATU and 30 mmol of 2-amino-2-(1H-imidazol-2-yl)ethan-1-ol hydrochloride. Then, add DIPEA (60 mmol) dropwise at room temperature. Allow to react at room temperature for 2 hours. After the reaction, remove the solvent and purify on silica gel (ethyl acetate / petroleum ether = 1 / 4) to obtain Intermediate 1. Intermediate product 1 was dissolved in an appropriate amount of tetrahydrofuran and transferred to a single-necked flask. The mixture was stirred at approximately 0°C for 5 minutes, and then p-toluenesulfonyl chloride (32 mmol) was slowly added dropwise to the reaction system. After the addition was complete, the mixture was warmed to room temperature and reacted for 6 hours. LC-MS analysis confirmed complete reaction of the starting material. The solvent was removed by swirl, and the mixture was extracted three times with ethyl acetate and water. The organic phases were combined, dried over anhydrous sodium sulfate, and the solvent was removed by swirl to obtain intermediate product 2, which was used directly in the next step. Intermediate product 2 was dissolved in an appropriate amount of tetrahydrofuran and transferred to a single-necked flask. DIPEA (71 mmol) was added and the temperature was raised to 75°C for 10 hours. The reaction was monitored for complete reaction by LC-MS. The solvent was removed by vortexing the reaction solution, and the product was extracted three times with ethyl acetate and water. The organic phases were combined, dried over anhydrous sodium sulfate, the solvent was evaporated, and purified on silica gel (ethyl acetate / petroleum ether = 1 / 3) to obtain compound D-1. 1 H NMR: δ 4.51-4.67 (3H, 4.59 (dd, J = 13.5, 7.4Hz), 4.60 (dd, J = 7.8, 6.9 Hz)), 7.21 (1H, d, J = 3.3 Hz), 7.33-7.46 (2H,7.39 (d, J = 4.3 Hz), 7.41 (d, J = 3.3 Hz)), 7.62 (1H, d, J = 4.3 Hz). 13 CNMR: δ 56.8 (1C, s), 69.7 (1C, s), 119.7-119.8 (2C, 119.7 (s), 119.7 (s)), 122.0-122.1 (2C, 122.0 (s), 122.0 (s)), 146.5 (1C, s), 153.1 (1C, s), 155.2(1C, s). 5. Preparation of coating: Weigh 30 parts by weight of modified rosin-based resin, 25 parts by weight of cyclohexanone, 10 parts by weight of diethyl phthalate, 6 parts by weight of borax, 3 parts by weight of modified alumina, 3 parts by weight of modified silica, 4 parts by weight of compound D-1, 7 parts by weight of sodium hexametaphosphate dispersant, and 7 parts by weight of leveling agent BYK-333; mix the modified rosin-based resin and diethyl phthalate with mechanical stirring; add borax, modified alumina, and modified silica to cyclohexanone and fully disperse; slowly mix the two; then mix and add compound D-1, sodium hexametaphosphate dispersant, and leveling agent BYK-333, and after fully dispersing, obtain the coating of Example 1.

[0047] Comparative Example 1: The steps of Comparative Example 1 are the same as those of Example 1, except that an equal mass of acrylic rosin (commercially available) is used in place of the modified rosin-based resin prepared in Example 1.

[0048] Comparative Example 2: The steps of Comparative Example 2 are the same as those of Example 1, except that an equal mass of rosin-based glycol diglycidyl acrylate (rosin-based glycol diglycidyl acrylate is prepared by the following steps: adding rosin acrylate and triethylamine to a four-necked flask equipped with a stirrer, a condenser, a dropping funnel, and a nitrogen conduit, heating to melt the rosin acrylate, adding butanediol diglycidyl ether dropwise, and reacting for 2 hours) is used instead of the modified rosin-based resin prepared in Example 1.

[0049] Comparative Example 3: The steps of Comparative Example 3 are the same as those of Example 1, except that an equal mass of rosin glycerol ester is used in Comparative Example 3 instead of the modified rosin-based resin prepared in Example 1.

[0050] Comparative Example 4: The steps of Comparative Example 4 are the same as those of Example 1, except that benzotriazole is used in place of the compound D-1 prepared in Example 1.

[0051] Comparative Example 5: The steps of Comparative Example 5 are the same as those of Example 1, except that the intermediate product 1 is used instead of the compound D-1 prepared in Example 1.

[0052] Corrosion resistance test: The corrosion resistance of the coatings of Example 1 and Comparative Examples 1-4 was tested using the following method: the samples of Example 1 and Comparative Examples 1-4 were coated on 50mm×50mm×2mm stainless steel test pieces with a film thickness of about 50μm; after coating, the film was cured at 180°C for 30 minutes. The cured stainless steel test piece was placed in a salt spray test chamber and tested according to GB / T1771-2007 "Determination of Neutral Salt Spray Resistance of Paints and Varnishes" and with the parameters appropriately modified to comply with the present invention. The test temperature was increased to 50°C, and the salt spray concentration was controlled to 5%. The test time was 500 hours, during which the corrosion condition of the test piece was recorded every 100 hours. After the test, the corrosion condition of the test piece was evaluated according to ASTMD714, and the coating surface was observed for rust, bubbles, or shedding. The experimental results showed that: The sample treated in Example 1 had no rust and almost no blistering; Comparative Example 1 was slightly rusted, the coating had local cracks and local shedding, and the bubble density was low; Comparative Example 2 was slightly rusted, the coating had local cracks and local shedding, and the bubble density was low; Comparative Example 3 was slightly rusted, the coating had local cracks and local shedding, and the bubble density was low; Comparative Example 4 had moderate rust, cracks and peeling of the coating, and medium bubble density; Comparative Example 5 was severely rusted, the coating cracked and fell off, and the bubble density was high.

[0053] The corrosion resistance test proves that 1) the rosin material modified by the present application has better corrosion resistance than other rosin materials; 2) the corrosion resistance principle of the compound D-1 prepared by the present application and the benzotriazole used in the prior art are similar: that is, the nitrogen atoms in the molecules have lone pairs of electrons, which can form stable coordination bonds with metal ions on the metal surface, thereby chemically adsorbing on the metal surface. This adsorption enables the compound D-1 or benzotriazole to form a dense protective film on the metal surface. The thickness of this film is usually less than 50 angstroms, which may be a monolayer, which can effectively isolate the metal from the external environment and prevent the metal from being oxidized and corroded; in addition, the nitrogen atoms in the compound D-1 molecule prepared by the present application have a higher density of lone pairs of electrons, so the coordination effect is better, and therefore has better corrosion resistance than benzotriazole, which is why Example 1 has better corrosion resistance than Comparative Example 4; Comparative Example 5, which directly uses the intermediate product 1, has poor corrosion resistance because its molecular structure cannot form a planar structure like Example 1, making it difficult to form a monolayer protective film.

[0054] Those skilled in the art will readily appreciate other embodiments of the present disclosure after considering the specification and practicing the disclosure disclosed herein. This disclosure is intended to cover any variations, uses, or adaptations of the present disclosure that follow the general principles of the present disclosure and include common knowledge or customary techniques in the art not disclosed herein.

Claims

1. A coating for metal protection, characterized in that: The coating comprises the following components in parts by weight: 25-35 parts by weight of modified rosin-based resin, 15-25 parts by weight of cyclohexanone, 5-10 parts by weight of diethyl phthalate, 5-10 parts by weight of borax, 1-5 parts by weight of modified alumina, 1-5 parts by weight of modified silicon oxide and 5-35 parts by weight of auxiliary agents.

2. The coating for metal protection according to claim 1, characterized in that: The modified alumina is alumina nanoparticles that have been lipophilically modified. The lipophilic modification process includes the following steps: Step 1-a: providing aluminum oxide nanoparticles, and dispersing the aluminum oxide nanoparticles in anhydrous ethanol; Step 2-a: adding hexadecyltrimethoxysilane, water, and glacial acetic acid to the anhydrous ethanol in sequence, and stirring at room temperature for 2-3 hours to obtain a first mixed solution; Step 3-a: Add E51 epoxy resin solution and acetone to the first mixed solution and stir for 0.5-1 hour to obtain a second mixed solution; Step 4-a: spraying the second mixed solution onto a substrate, and then letting it stand for 2-3 hours, collecting the product, washing it, and drying it to obtain the oleophilically modified aluminum oxide nanoparticles.

3. The coating for metal protection according to claim 1, characterized in that: The modified silicon oxide is silicon oxide nanoparticles that have been lipophilically modified; the lipophilic modification process includes the following steps: Step 1-b: providing silicon oxide nanoparticles, and dispersing the silicon oxide nanoparticles in anhydrous ethanol; Step 2-b: adding aqueous ammonia to the anhydrous ethanol, maintaining stirring, adding trimethoxy(3-methoxypropyl)silane dropwise to the solution, then heating to 45°C-55°C, and continuing stirring for 2-3 hours to obtain a third mixed solution; Step 3-b: Cool the third mixed solution to room temperature, dissolve hexadecyl acrylate in anhydrous ethanol, add the solution to the third mixed solution, continue stirring for 1-2 hours, filter, wash, and dry to obtain the lipophilically modified silicon oxide nanoparticles.

4. The coating for metal protection according to claim 1, characterized in that: The modified rosin-based resin is prepared by the following steps: Step 1-c: Add rosin-based glycol diglycidyl acrylate and methylphenyldimethoxysilane to a reaction vessel, heat to 90°C-100°C, keep stirring, then add a catalyst, react for 4-5 hours, and then cool to 75°C-80°C; Step 2-c: Add formaldehyde and tung oil to the cooled reaction vessel, continue the reaction for 3-4 hours, then cool to 40°C-50°C and maintain the temperature for 6-12 hours, then collect the orange-red transparent viscous liquid at the bottom layer to obtain the modified rosin-based resin.

5. The coating for metal protection according to claim 1, characterized in that: The auxiliary agent comprises at least one of a defoamer, a dispersant and a leveling agent; wherein: The defoamer is selected from tributyl phosphate, defoamer Deqian 3100 or defoamer BYK088; The dispersant is selected from polycarboxylate dispersant 5040 or sodium hexametaphosphate; The leveling agent is selected from leveling agent BYK-333 or organic silicon leveling agent HY-5030.

6. The coating for metal protection according to claim 1, characterized in that: The coating further comprises 2-8 parts by weight of compound D, wherein the compound D has the following structural formula: wherein R1 and R2 are each independently selected from hydrogen, a halogen atom, a nitro group, an amino group, a cyano group, a hydroxyl group, a carboxyl group, a substituted or unsubstituted C1-C30 alkyl group, a substituted or unsubstituted C2-C30 alkenyl group, a substituted or unsubstituted C2-C30 alkynyl group, a substituted or unsubstituted C1-C30 alkoxy group, a substituted or unsubstituted C3-30 cycloalkyl group, a substituted or unsubstituted C6-C30 aryl group, a substituted or unsubstituted 3-30 membered heterocyclyl group, or a substituted or unsubstituted 5-30 membered heteroaryl group.

7. The coating for metal protection according to claim 6, characterized in that: The coating further comprises 2-8 parts by weight of compound D-1, wherein the compound D-1 has the following structural formula: .

8. A method for preparing the coating for metal protection according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: Step 1-d: preparing a modified rosin-based resin; Step 2-d: mixing the modified rosin-based resin and diethyl phthalate with mechanical stirring; Step 3-d: preparing oleophilic modified aluminum oxide nanoparticles and oleophilic modified silicon oxide nanoparticles, adding borax, the prepared modified aluminum oxide, and the modified silicon oxide into cyclohexanone and fully dispersing them; Step 5-d: Prepare compound D-1 and mix it with an auxiliary agent; Step 6-d: slowly mix the product obtained in step 3-d and the product obtained in step 2-d, and then add the product obtained in step 5-d to obtain the coating for metal protection.

9. The method according to claim 8, characterized in that Step 5-d further comprises the following steps: Step 1-e: using imidazole-2-carboxylic acid and 2-amino-2-(1H-imidazol-2-yl)ethan-1-ol hydrochloride as raw materials, condensing to obtain intermediate 1; ; Step 2-e: reacting intermediate 1 with p-toluenesulfonyl chloride to obtain intermediate 2; ; ； Step 3-e: reacting the intermediate product 2 with N,N-diisopropylethylamine to obtain compound D-1; 。

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