Rosin-based waterborne anticorrosive coating resin, and preparation method and application thereof

Abstract

The application belongs to the field of rosin resin, and provides a rosin-based waterborne anticorrosive coating resin and a preparation method and application thereof, which comprises the following steps: alcoholysis of vegetable oil to obtain an alcoholysis product; addition of long-chain saturated dibasic acid to the alcoholysis product to perform esterification reaction to obtain a prepolymer; addition of rosin to unsaturated acid and / or unsaturated acid anhydride to obtain a rosin-based adduct; reaction of the rosin-based adduct with the prepolymer to obtain a waterborne resin precursor; and amination of the waterborne resin precursor into a salt to obtain the rosin-based waterborne anticorrosive coating resin. Compared with the prior art, the application improves the use value of rosin and vegetable oil in the field of waterborne anticorrosive coating resin, the prepared resin has excellent properties such as good strength, gloss and corrosion resistance, and the raw materials are more environmentally friendly.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of rosin resins, and particularly relates to a rosin-based waterborne anticorrosive coating resin as well as a preparation method and application thereof. BACKGROUND

[0002] With the impact of the oil energy crisis and the enhancement of people's environmental awareness, the coating industry gradually turns to the direction of saving resources, energy, reducing pollution, being conducive to ecological balance and improving economic efficiency. Because the traditional solvent-based organic coating has a high content of volatile organic compounds (Volatile Organic Compound, VOC for short), a large amount of organic solvents will be released in the process of its construction and drying, which causes great threat to the environment and human health. In recent years, countries have been working on the research and development of environmentally friendly coatings, among which, high solid solvent-based coatings, solvent-free powder coatings, ultraviolet light curing coatings and water-based coatings have emerged. Compared with the first three environmentally friendly coatings, water-based coatings have their unique advantages: compared with high solid coatings, the amount of organic solvents contained in water-based coatings is greatly reduced, which not only saves resources but also is environmentally friendly; compared with powder coatings, water-based coatings have simple production equipment and can form a film at room temperature, which saves energy; compared with ultraviolet light curing coatings, water-based coatings do not require large production equipment and high energy consumption, and can be produced into various complex-shaped products by spraying, brushing, dipping, etc.

[0003] Water-based coatings are prepared by dispersing their main components, such as water-based resins, pigments, fillers and additives, etc. with water as the medium, and the most prominent feature is to use water as the solvent, a small amount of low-toxicity ether alcohol organic solvent or no use at all, which has the characteristics of economy, environmental protection and safety, so it is used as an environmentally friendly coating. Water-based coatings are coated on the substrate, and the water-based resin on the substrate surface forms a film to play a shielding role, a slow-burning role or a cathodic protection role, etc. to realize the protection of the substrate, so the anticorrosive effect depends on the performance of the water-based resin, but ordinary water-based resins have some performance defects, such as slow drying of the paint film, poor storage stability, poor water resistance and stain resistance, and poor hydrolysis resistance due to containing a large amount of ester bonds. In order to obtain water-based coatings with higher performance, better effect and wider application, the main component of water-based resin needs to be improved.

[0004] Rosin is a rich renewable resource, and is an important chemical raw material, widely used in paint, ink, coating and other industries. Rosin contains carboxyl and double bond, which can be esterified, addition and other modification reactions. In addition, the two active centers in rosin can introduce rosin skeleton into other materials, giving other materials such as corrosion, moisture and insulation and other physical and chemical properties, while the strong rigid phenanthrene ring structure in rosin has a significant impact on the tackiness, film forming and gloss of the resin, and these properties are the characteristics needed to improve the defects of water-based resin. As a renewable resource, plant oil is widely available, green and environmentally friendly, and low in price. The functionality of plant oil is low, which can be used to reduce the average functionality of the system and reduce the possibility of gel. By adjusting the amount of plant oil added, the ratio of rigid and flexible groups in the molecular structure of the resin can be controlled to regulate the performance of the resin. Dry and semi-dry plant oil, due to the presence of a large number of double bonds in the molecule, reacts with oxygen in the air to form hydroperoxide first; then the hydroperoxide decomposes to produce alkyl radicals, which polymerize under the action of free radicals to form a macromolecular network structure, thereby forming a film on the substrate surface to protect the substrate and prevent corrosion.

[0005] CN104072742A discloses an epoxy modified waterborne alkyd resin and waterborne alkyd amino baking paint and a preparation method. The preparation method is first mixing plant oil, bisphenol A type glycidyl ether epoxy resin and polyol to synthesize alcoholysis product glyceride, then esterifying with phthalic anhydride, then waterizing with trimellitic anhydride, and finally neutralizing and dispersing to obtain an epoxy modified waterborne alkyd resin; the obtained waterborne alkyd resin is mixed with different types of amino resin, and a certain amount of pigment, cosolvent, neutralizing agent and deionized water to obtain an amino baking paint. The invention improves the hardness, adhesion, water resistance, outdoor weather resistance and other problems of ordinary waterborne alkyd resin to some extent by introducing epoxy resin. Moreover, the invention introduces a large amount of environmentally friendly plant oil for modification, which meets the environmental and economic concepts. However, a large amount of aromatic hydrocarbon organic solvent (xylene) is used as a refluxing reagent in the resin synthesis process, and the epoxy resin used itself has certain toxicity, which is contrary to the concept of environmentally friendly water-based paint. At the same time, the invention does not involve the introduction and use of rosin.

[0006] Coupling solvent effects on water-reducible alkyd resings by Vance RG et al. mentioned that semi-synthetic monomer maleic rosin obtained by the reaction of rosin and maleic anhydride can be used as part of the polybasic acid to participate in the synthesis of water-based alkyd resin, and a series of maleic rosin was synthesized by changing the ratio of rosin to maleic anhydride, and was applied to water-based alkyd resin to prepare different kinds of water-based alkyd resin, and its performance was analyzed. It was found that when the ratio of rosin to maleic anhydride was 1:1, the water-based alkyd resin prepared was difficult to dry to the touch and had low hardness. In addition, the article also mentioned that the less the proportion of rosin, the less the benzene ring structure in the synthesized maleic rosin, and the pencil hardness will be reduced, and the proportion of maleic anhydride is increased, and the storage stability will be poor. When the ratio of rosin to maleic anhydride is 4:1, the paint film drying time is the fastest, and the hardness and stability are relatively good. However, this article only uses rosin adduct as an auxiliary of polybasic acid, so the amount of rosin used is extremely limited, and the improvement of the performance of the final resin is not great, and it is not environmentally friendly and economical.

[0007] WO2022244278A1 discloses a rosin modified polyester resin and its application in waterborne coatings. The synthesis steps of this kind of resin are as follows: first, rosin modified addition resin is prepared by the addition reaction of rosin and unsaturated dibasic acid (fumaric acid / maleic anhydride / itaconic acid); second, esterification reaction of tribasic alcohol glycerol (partially added dibasic alcohol ethylene glycol) with dibasic acid (succinic acid / hexanedioic acid) is carried out, in which part of the examples add floating oil fatty acid for modification, or first alcoholysis of vegetable oil (linseed oil) with glycerol, then esterification reaction with the above-mentioned dibasic acid or fatty acid to obtain alkyd resin, and finally the prepared addition resin is reacted with the alkyd resin to obtain the rosin modified polyester resin. Due to the introduction of rosin adduct with strong rigid structure, the prepared rosin modified polyester applied in waterborne coatings has excellent oil resistance and stain resistance when coated on the surface of the substrate. However, due to the excessive use of unsaturated acid during the addition of rosin and unsaturated acid, these excess unsaturated acids hinder the oxidation of vegetable oil to form a film during the use of water-based resin, affecting the corrosion protection effect on the surface of the substrate. In addition, the excessive free unsaturated acid leads to high acid value of the resin, and the acid value of the resin prepared by the invention is not less than 65, and the highest reaches 175. The high acid value leads to high content of polar groups in the resin, resulting in high free water content and high bound water content in the prepared coating film, and more "polar water channels" leading to strong water absorption of the coating layer, resulting in poor storage stability and poor water resistance.

[0008] The common water-based resin has some defects in performance, and the film dries slowly, and has poor oil resistance and stain resistance due to low internal rigidity. Due to the need for hydrophilicity, strong polar functional groups are often introduced into the resin, and the content of these polar groups has a great influence on the performance of the resin. When the content of the polar groups in the resin is too low, the free water content is much higher than the bound water content, and then more "defect water channels" are formed, which leads to water absorption of the anticorrosive coating. When the content of the polar groups is too high, both the free water content and the bound water content are high, and then "polar water channels" with more significant water absorption and swelling are formed, which also leads to water absorption of the anticorrosive coating. Only when the content of the polar groups is appropriate, both the free water content and the bound water content are low, and the degree of water absorption and swelling is also small. Therefore, it is necessary to explore a rosin-based modified water-based resin which can effectively solve the problems of slow drying time, poor storage stability, poor water resistance and poor stain resistance of the common water-based anticorrosive coating resin. SUMMARY

[0009] The present application provides a rosin-based water-based anticorrosive coating resin and its preparation method and application. First, the alcoholysis product is prepared by alcoholysis of vegetable oil, and the prepared alcoholysis product is subjected to esterification reaction with long-chain saturated dibasic acid to obtain a prepolymer. At the same time, the rosin is subjected to sufficient addition with unsaturated acid and / or unsaturated anhydride to prepare a rosin-based adduct. Then, the prepolymer is added to the rosin-based adduct for reaction. The water-based resin precursor with appropriate content of polar groups and appropriate acid value is prepared by controlling the amount of the two substances. Finally, the obtained water-based resin precursor is subjected to amination to prepare a salt to obtain the rosin-based water-based anticorrosive coating resin.

[0010] The present application introduces the strong rigid double-tricyclic phenanthrene structure into the rosin-based adduct by sufficient addition of rosin and unsaturated acid, which improves the film drying speed, oil resistance, stain resistance, gloss and strength of the water-based coating prepared therefrom. Due to the introduction of the strong rigid rosin group, the hydrolysis of the ester bond in the resin molecule is inhibited to some extent, thereby enhancing the water resistance of the rosin-based water-based coating resin.

[0011] However, the introduction of the strong rigid rosin-based double-tricyclic phenanthrene structure alone will lead to low film adhesion and brittleness of the later-stage resin, so the long-chain flexible saturated dibasic acid is added to the prepolymer for reaction with the rosin-based adduct to neutralize the rigidity of the adduct, so as to achieve rigidity and flexibility balance.

[0012] In addition, the introduced vegetable oil is subjected to alcoholysis to some extent, and the long-chain hydrophobic groups thereof can also play a shielding role on the polar groups in the resin molecule, thereby enhancing the anticorrosive performance of the coating. At the same time, the introduction of these long-chain hydrophobic groups can also prevent the interaction between the hydroxyl groups in the alcohol molecule to some extent, improve the compatibility of the resin with other auxiliary materials, and reduce the hydrolysis of the resin to some extent, thereby enhancing the water resistance of the water-based coating.

[0013] To achieve the above object, the technical scheme adopted by the present application is as follows:

[0014] A preparation method of a rosin-based waterborne anticorrosive coating resin comprises the following steps:

[0015] (1) alcoholysis of vegetable oil to obtain an alcoholysis product;

[0016] (2) adding a long-chain saturated dibasic acid to the alcoholysis product obtained in step (1) to perform esterification reaction, thereby obtaining a prepolymer;

[0017] (3) addition of rosin with unsaturated acid and / or unsaturated acid anhydride to obtain a rosin-based adduct;

[0018] (4) reaction of the rosin-based adduct in step (3) with the prepolymer obtained in step (2) to obtain a waterborne resin precursor;

[0019] (5) amination of the waterborne resin precursor in step (4) into a salt, thereby obtaining a rosin-based waterborne anticorrosive coating resin.

[0020] Preferably, the vegetable oil in step (1) is one or more of dry vegetable oil and semi-dry vegetable oil.

[0021] Further preferably, the dry vegetable oil is one or more of tung oil, flaxseed oil, hempseed oil and catalpa oil; and the semi-dry vegetable oil is one or more of soybean oil, cottonseed oil and sunflower seed oil.

[0022] Most preferably, the dry vegetable oil is flaxseed oil; and the semi-dry vegetable oil is soybean oil.

[0023] Preferably, the alcoholysis in step (1) comprises the step of adding alcohol and a catalyst to the vegetable oil.

[0024] Further preferably, the alcohol is one or more of polyhydric alcohols; and the catalyst is one or more of inorganic bases.

[0025] More preferably, the polyhydric alcohol is one or more of glycerol, trimethylolpropane, quaternary alcohol, or one or more of glycerol, trimethylolpropane and quaternary alcohol mixed with one or more of ethylene glycol, diethylene glycol, triethylene glycol and neopentyl glycol; and the inorganic base is one or more of LiOH, NaOH, KOH, Mg(OH)2 and Ca(OH)2.

[0026] Still further preferably, the polyol is one or both of trimethylolpropane and pentaerythritol, or is a mixed alcohol of one or both of trimethylolpropane and pentaerythritol with one or both of ethylene glycol and diethylene glycol; the inorganic base is one or more of LiOH, KOH, and Mg(OH)2.

[0027] Most preferably, the polyol is trimethylolpropane, or is a mixed alcohol of trimethylolpropane and diethylene glycol; the inorganic base is LiOH.

[0028] Preferably, the amount of the catalyst used is 1-6‰ of the total mass of the vegetable oil.

[0029] Most preferably, the amount of the catalyst used is 2-4‰ of the total mass of the vegetable oil.

[0030] Preferably, the alcoholysis in step (1) requires heating, and the heating temperature is 210-250℃.

[0031] Further preferably, the heating temperature is 220-230℃.

[0032] Preferably, the long-chain saturated dibasic acid in step (2) is one or more of saturated dibasic acids with carbon atom number of 8 or more.

[0033] Further preferably, the long-chain saturated dibasic acid is one or more of octanedioic acid, decanedioic acid, dodecanedioic acid, and tetradecanedioic acid.

[0034] Still further preferably, the long-chain saturated dibasic acid is one or both of decanedioic acid and dodecanedioic acid.

[0035] Most preferably, the long-chain saturated dibasic acid is decanedioic acid.

[0036] Preferably, the esterification reaction in step (2) requires heating, and the heating temperature is 190-230℃.

[0037] Further preferably, the heating temperature is 200-220℃.

[0038] Preferably, the rosin in step (3) is one or more of gum rosin, wood rosin, and tall oil rosin; the gum rosin is one or more of Masson's pine rosin, slash pine rosin, and Sichuan pine rosin.

[0039] Further preferably, the rosin is one or both of gum rosin and tall oil rosin; the gum rosin is one or more of Masson's pine rosin, slash pine rosin, and Sichuan pine rosin.

[0040] Most preferably, the rosin is one or both of Masson's pine rosin and Sichuan pine rosin.

[0041] Preferably, the unsaturated acid and / or unsaturated anhydride in step (3) is one or more of unsaturated dibasic acid and unsaturated dibasic anhydride.

[0042] Further preferably, the unsaturated acid and / or unsaturated anhydride is one or more of fumaric acid, maleic acid, maleic anhydride, itaconic acid and citraconic acid.

[0043] More preferably, the unsaturated acid and / or unsaturated anhydride is one or more of fumaric acid, maleic acid and maleic anhydride.

[0044] Most preferably, the unsaturated acid and / or unsaturated anhydride is fumaric acid.

[0045] Preferably, the amount of the unsaturated acid and / or unsaturated anhydride in step (3) is 19.2-31.5% of the mass of the rosin.

[0046] Preferably, the addition in step (3) requires heating, and the heating temperature is 180-220℃.

[0047] Further preferably, the heating temperature is 190-210℃.

[0048] Preferably, the reaction in step (4) requires heating, and the heating temperature is 210-250℃.

[0049] Further preferably, the heating temperature is 220-240℃.

[0050] Preferably, the amination and salification in step (5) comprises the step of adding an organic base to the aqueous resin precursor.

[0051] Further preferably, the organic base is one or more of organic amines.

[0052] More preferably, the organic base is one or more of triethylamine, dimethylethanolamine, triethanolamine and diethanolamine, diphenylamine and triphenylamine.

[0053] Still more preferably, the organic base is one or more of triethylamine, triethanolamine and diphenylamine.

[0054] Most preferably, the organic base is triethylamine.

[0055] Compared with the prior art, the present application has the following advantages:

[0056] (1) The present application provides a rosin-based aqueous anticorrosive coating resin, the raw material rosin and vegetable oil used in the resin are natural renewable resources and are abundant in source; the prepared resin can be widely used in products in the coating industry and is more environmentally friendly.

[0057] (2) The strong rigid bistricyclic phenanthrene and strong flexible long-chain saturated acid introduced in the preparation process of the rosin-based waterborne anticorrosive coating resin improves the drying speed, oil resistance, stain resistance, gloss and strength of the waterborne coating film.

[0058] (3) The rosin-based waterborne anticorrosive coating resin controls the hydrophilic-hydrophobic balance of the polar groups and nonpolar groups of polyols and vegetable oils through alcoholysis reaction, not only enhances the corrosion resistance of the coating, but also to some extent prevents the interaction between hydroxyl groups in alcohol molecules, improves the compatibility of the resin with other auxiliary materials, and to some extent reduces the hydrolysis of the resin, enhances the water resistance and storage stability of the coating.

[0059] (4) When polyols are used to alcoholysis of vegetable oils, the addition of diols can reduce the functionality of the polybasic acid and polyol mixture in the reaction system to some extent, effectively solving the problem of easy gelation of polyols in such reactions. In addition, the addition of low-boiling diols to some extent plays a refluxing role, which can replace the organic solvent that plays a refluxing role, thereby realizing solvent-free environmental protection production and preparation.

[0060] (5) Compared with the prior art, the present application improves the use range and value of rosin and vegetable oil in the field of waterborne anticorrosive coating resin, and the prepared rosin-based waterborne anticorrosive coating resin has good strength, gloss and water resistance, while reducing the use of organic solvents in the reaction process, and the main raw material is renewable rosin and vegetable oil, which is more environmentally friendly. BRIEF DESCRIPTION OF DRAWINGS

[0061] Figure 1 UV-visible spectra of raw materials in Example 1, soybean oil, trimethylolpropane, sebacic acid and alcoholysis product obtained by reaction, wherein 1 represents soybean oil, 2 represents trimethylolpropane, 3 represents sebacic acid, and 4 represents the alcoholysis product obtained by reaction;

[0062] Figure 2 UV-visible spectra of raw materials in Example 1, Masson's pine rosin and rosin-based adduct obtained by reaction of Masson's pine rosin and fumaric acid, wherein 5 represents Masson's pine rosin, and 6 represents the rosin-based adduct obtained by reaction;

[0063] Figure 3 UV-visible spectra of alcoholysis product, rosin-based adduct and rosin-based resin product 1 obtained by reaction of rosin-based adduct in Example 1, wherein 4 represents the alcoholysis product, 6 represents the rosin-based adduct, and 7 represents the rosin-based resin product 1;

[0064] Figure 4The infrared spectra of the raw materials in Example 1, soybean oil, trimethylolpropane, sebacic acid and the alcoholysis product obtained by reaction, wherein 1 represents soybean oil, 2 represents trimethylolpropane, 3 represents sebacic acid, and 4 represents the alcoholysis product obtained by reaction;

[0065] Figure 5 The infrared spectra of the raw materials in Example 1, Masson's pine rosin and the rosin-based adduct obtained by reaction with fumaric acid, wherein 5 represents Masson's pine rosin, and 6 represents the rosin-based adduct obtained by reaction;

[0066] Figure 6 The infrared spectra of the alcoholysis product, the rosin-based adduct and the rosin-based resin product 1 obtained by reaction of the alcoholysis product and the rosin-based adduct in Example 1, wherein 4 represents the alcoholysis product, 6 represents the rosin-based adduct, and 7 represents the rosin-based resin product 1. DETAILED DESCRIPTION

[0067] It should be noted that the raw materials used in the present application are all ordinary commercially available products, and their sources are not specifically limited.

[0068] Examples and Comparative Examples

[0069] The different values of the parameters based on the preparation method in the examples and comparative examples constitute different examples and comparative examples, and the parameters A, B, C, D, E, F, G, H, T1, T2, T3, T4, T5, t1, t2, t3, t4, t5, n are shown in Table 1, and Table 2 shows the specific types of raw materials used and the physical performance indicators of the rosin-based water-based anticorrosive coating resins prepared.

[0070] Example 1-8 A preparation method of a rosin-based water-based anticorrosive coating resin, comprising the following steps:

[0071] (1) heating and reacting plant oil with a mass of A, alcohol with a mass of B and catalyst with a mass of C, the heating temperature being T1 and the reaction time being t1, to obtain an alcoholysis product;

[0072] (2) adding long-chain saturated dibasic acid with a mass of D to the alcoholysis product obtained in step (1) and heating and reacting, the heating temperature being T2 and the reaction time being t2, to obtain a prepolymer;

[0073] (3) heating and melting rosin with a mass of E, adding unsaturated acid and / or unsaturated anhydride with a mass of F, heating and reacting, the heating temperature being T3 and the reaction time being t3, to obtain a rosin-based adduct;

[0074] (4) heating and melting the rosin-based adduct obtained in step (3), adding the prepolymer obtained in step (2) dropwise, and incubating and reacting, the incubation temperature being T4 and the reaction time being t4, to obtain a water-based resin precursor;

[0075] (5) The aqueous resin precursor obtained in step (4) is heated to T5, and an organic base with a mass of G is added dropwise for neutralization reaction, the reaction time is t5, and then deionized water with a mass of H is added for dispersion at a speed of n, to obtain a rosin-based aqueous anticorrosive coating resin.

[0076] Preparation method of a rosin-based aqueous anticorrosive coating resin

[0077] The difference between this comparative example and Example 1 is that the semi-drying vegetable oil in step (1) is replaced by a non-drying vegetable oil (castor oil).

[0078] Preparation method of a rosin-based aqueous anticorrosive coating resin

[0079] The difference between this comparative example and Example 1 is that the long-chain saturated dibasic acid in step (2) is replaced by a short-chain (carbon atom number < 8) saturated dibasic acid (hexanedioic acid).

[0080] Preparation method of a rosin-based aqueous anticorrosive coating resin

[0081] The difference between this comparative example and Example 1 is that the long-chain saturated dibasic acid in step (2) is replaced by a short-chain (carbon atom number < 8) saturated dibasic acid (hexanedioic acid).

[0082] Preparation method of a rosin-based aqueous anticorrosive coating resin

[0083] The difference between this comparative example and Example 1 is that the unsaturated acid and / or unsaturated anhydride (parameter F) in step (3) is used in excess, and the amount is 36.3% of the mass of the rosin (parameter E).

[0084] Table 1

[0085]

[0086] Table 2

[0087]

[0088] Test example

[0089] Specifically, the structure characterization and determination method of the related indexes of the rosin-based aqueous anticorrosive coating resins prepared in Examples 1-8 and Comparative Examples 1-4 are as follows:

[0090] UV: A UV-2550 double-beam UV-visible spectrophotometer (Shimadzu, Japan) is used for sample analysis, the scanning range is 190nm-380nm, the scanning accuracy is 1nm, and the sample is dissolved in ethyl acetate or methanol;

[0091] Infrared: FTIR-8400S Fourier Transform Infrared Spectrometer (Shimadzu, Japan) was used to determine the sample by KBr pressing or liquid mode method, and the determination wave number range was 4000-500 cm -1 ;

[0092] Appearance: The appearance of the resin and water dispersion solution was determined according to GB 1721-79 “Varnish, Varnish and Diluent Appearance and Transparency Determination Method”, the physical properties such as sample state, transparency and color were observed, and the test results are shown in Table 3;

[0093] Viscosity: The determination method referred to GB / T 2794-95 “Adhesive Viscosity Determination Method”, and the test results are shown in Table 3;

[0094] Solid content: The determination method referred to GB / T 1725-79 “Paint Solid Content Determination Method”, 1-2 grams of resin sample was weighed on a dry and clean surface dish which had been weighed, then placed in a drying oven at 160°C for a certain time, taken out and placed in a desiccator to cool to room temperature, weighed, then placed in an oven for 30 minutes, taken out and placed in a desiccator to cool to room temperature, weighed, until the weight difference between the two times was not more than 0.01 grams. Two samples were determined in parallel, and the average value was calculated according to the relevant formula, and the test results are shown in Table 3;

[0095] Acid value: According to GB 6743-86 “Determination of Paint Acid Value for Lacquer and Varnish”, the sample was weighed into a conical flask, accurately to 1 mg, 25 ml of mixed solvent (95% ethanol and toluene mixed reagent with a volume ratio of 1:2) was added to dissolve the sample completely. 2-4 drops of phenolphthalein indicator solution was added to the sample solution, immediately titrated to the end point (the solution was pink, and did not fade within 30s) with 0.1 mol / L KOH ethanol standard solution, and the volume of KOH ethanol standard solution consumed at the titration end point was recorded. The same amount of mixed solvent was used for blank test, and the volume of KOH ethanol standard solution consumed was recorded, and the test results are shown in Table 3 according to the relevant formula;

[0096] Paint film preparation: According to the national standard GB / T 1727-79 “General Preparation Method of Paint Film”, the sample was brushed on the specified test plate with a paint brush, quickly and evenly brushed in the longitudinal and transverse directions to form a uniform paint film, and no bare bottom phenomenon was allowed. The brushed sample was placed in a constant temperature and humidity environment as required to dry, and the performance was measured, and the test results are shown in Table 4;

[0097] Gloss: The gloss of the paint film was tested by WGG-60 mirror portable gloss meter according to GB 1748-79 “Paint Film Drying Determination Method”. Five different positions were selected for determination, and the arithmetic mean value was taken, and the test results are shown in Table 4;

[0098] Surface dry time: refer to the surface dry test method - ethyl method in GB 1728-79 "Determination of dry time of paint film and putty film", touch the surface of the paint film with finger, if the film is sticky but no paint is adhered to the hand, it is considered that the surface is dry. Use a stopwatch to time, each group of samples is tested three times, and the average value is taken, the test results are shown in Table 4;

[0099] Actual dry time: according to the filter paper method in GB / T 1728-79 "Determination of dry time of paint film and putty film", first place a piece of qualitative filter paper on the paint film, press lightly for 30 s, then turn the sample plate so that the paint film faces down, if the filter paper can fall freely and the filter paper fibers are not adhered to the paint film, it is considered that the paint film reaches actual dry, use a stopwatch to time, each group of samples is tested three times, and the average value is taken, the test results are shown in Table 4;

[0100] Water resistance: refer to the water immersion test method in GB / T 1733-93 "Determination of water resistance of paint film", add distilled water or deionized water in a beaker, at room temperature, put three test panels into the water, immerse each sample completely in the water for two weeks, observe the changes of the coating (whether white, blistering, peeling, etc. occur), the test results are shown in Table 4;

[0101] Acid, alkali and salt resistance: according to the method in GB 9274-88 "Determination of liquid medium resistance of color paint and varnish", select method A (immersion method): at room temperature, immerse 2 / 3 of each group of three test panels in 0.1 mol / L sulfuric acid aqueous solution, 0.1 mol / L NaOH aqueous solution and 3% NaCl solution, respectively, observe and record the changes of the coating (whether white, blistering, peeling, etc. occur), the test results are shown in Table 4;

[0102] Hardness: the hardness of the paint film is tested according to the B method manual method in GB / T 6739-96 "Determination of film hardness by pencil method": use a Chinese pencil to push and press the coating at an angle of 45° at a speed of 1 cm / s for 1 cm, push and press the same hardness pencil for 5 times, if there are two (or more) scratches or breaks, record the hardness type of the next pencil, otherwise, continue to test with the previous type, until it is broken or scratched; the test range is 4B-6H, the test results are shown in Table 4;

[0103] Adhesion: The adhesion of the paint film was determined according to GB / T 1720-79 "Test Method for Adhesion of Paint Films". The sample was placed with the paint film side up on a hard, level surface. Using a blade, six parallel cut lines were made on the paint film with a 1mm spacing. Then, six more parallel cut lines were made perpendicularly to the original cut lines at 90° angles, with a 1mm spacing, forming a grid. Transparent tape was then applied to the sample. Holding one end of the tape suspended at a 60° angle to the sample surface, the tape was smoothly peeled off within 0.5–1.0 seconds. The degree of paint film damage was observed, and the cross-cut test grade was recorded. The results were expressed as 0–5, with 5 being the worst and 0 the best. The test results are shown in Table 4.

[0104] Storage stability: Tested according to the national standard GB / T 6753.3-86 "Test Method for Storage Stability of Coatings", and the test results are shown in Table 4;

[0105] Table 3

[0106] Example Appearance Viscosity / cp Solid content / % Acid value / mg KOH g -1 ]] Example 1 Reddish-brown transparent viscous liquid 432 50 58 Example 2 Reddish-brown transparent viscous liquid 405 50 53.5 Example 3 Reddish-brown transparent viscous liquid 465 48.5 60 Example 4 Reddish-brown transparent viscous liquid 353 49.3 50 Example 5 Reddish-brown transparent viscous liquid 422 51 55 Example 6 Reddish-brown transparent viscous liquid 317 48.3 52.5 Example 7 Reddish-brown transparent viscous liquid 386 50.6 54 Example 8 Reddish-brown transparent viscous liquid 377 52 57 Comparative Example 1 Reddish-brown transparent viscous liquid 336 50.3 52.3 Comparative Example 2 Reddish-brown transparent viscous liquid 403 49.7 50.5 Comparative Example 3 Reddish-brown transparent viscous liquid 386 49.3 48.2 Comparative Example 4 Reddish-brown transparent viscous liquid 597 50.7 81.6

[0107] To confirm the prepared rosin resin, ultraviolet-visible spectroscopy (UV-vis) was used to characterize this type of resin. The test results for alcoholysis products, rosin-based adducts, and rosin resin products, along with those for raw material vegetable oil, polyols (mixed alcohols of polyols and diols), long-chain diacids, unsaturated acids, and rosin, are as follows: Figure 1 , Figure 2 , Figure 3 As shown. Due to structural similarities, resin product 1 from Example 1 and raw materials soybean oil, trimethylolpropane, sebacic acid, fumaric acid, and rosin were selected for testing and analysis. Figure 1 It can be seen that the strong characteristic absorption peak at 255 nm, belonging to soybean oil, shifts to 253 nm after undergoing alcoholysis esterification with trimethylolpropane and sebacic acid. This indicates that the strong electron-withdrawing hydroxyl and carboxyl groups of trimethylolpropane and sebacic acid, after being attached to the soybean oil chain, have a decolorizing effect. Conversely, the strong characteristic absorption peaks at 203 nm, belonging to trimethylolpropane, and 208 nm, belonging to sebacic acid, shift to 253 nm after reacting with soybean oil. This indicates that the long-chain alkyl groups of soybean oil, which donate electrons, have an auxochromic effect. Furthermore, the figure also shows that the characteristic absorption peaks at 270 nm and 280 nm, belonging to soybean oil, broaden and weaken after the reaction, indicating that the alcoholysis esterification of soybean oil with trimethylolpropane and sebacic acid successfully generates a prepolymer. Figure 2It can be seen that the characteristic absorption peak of 259 nm belonging to Masson's pine is blue-shifted to 253 nm after the reaction with fumaric acid, indicating that the strong electron-withdrawing carboxyl group plays a color-reducing role after the addition of fumaric acid to the Masson's pine chain. At the same time, a characteristic absorption peak of fumaric acid appears at 275 nm, indicating that fumaric acid is successfully added to the Masson's pine to form a rosin-based adduct. As can be seen from Figure 3 , after the reaction of the prepolymer with the rosin-based adduct, the characteristic absorption peak at 253 nm is red-shifted to 256 nm, which is due to the consumption of the electron-withdrawing hydroxyl group belonging to the prepolymer and the electron-withdrawing carboxyl group belonging to the rosin-based adduct through esterification. In summary, after the esterification of the alcoholysis product of soybean oil and polyol with long-chain dibasic acid and the addition of fumaric acid to the Masson's pine, the esterification reaction of the rosin-based waterborne anticorrosive coating resin is successfully synthesized.

[0108] In order to further confirm the prepared rosin-based waterborne anticorrosive coating resin, Fourier infrared spectroscopy (FTIR) was used to characterize the resin, and the test results of the alcoholysis product, rosin-based adduct and rosin resin product and raw materials such as vegetable oil, polyol (mixed alcohol of polyol and diol), long-chain dibasic acid, unsaturated acid and rosin are shown in Figure 4 , Figure 5 , Figure 6 Due to the similarity of the structure, the resin product 1 of Example 1 and the raw materials of soybean oil, trimethylolpropane, sebacic acid, fumaric acid and Masson's pine were selected for test analysis. As can be seen from Figure 4 , the ester carbonyl characteristic absorption peak of soybean oil at 1738 cm -1 is blue-shifted to 1735 cm -1 , the characteristic absorption peaks at 729 and 695 cm -1 are retained, but the intensity is obviously weakened, the hydroxyl characteristic absorption peak at 3355 cm -1 belonging to trimethylolpropane is not only red-shifted to 3398 cm -1 , but also the intensity is obviously weakened, and the characteristic peak of carboxyl carbonyl at 1698 cm -1 belonging to sebacic acid is obviously disappeared, indicating that the alcoholysis and esterification reaction of soybean oil with trimethylolpropane and sebacic acid is successfully generated prepolymer; as can be seen from Figure 5 , the carboxyl hydroxyl group at 3430 cm -1 of Masson's pine completely disappears after the addition reaction with fumaric acid, which may be related to the shielding effect of the strong rigid six-membered bridge compound generated after the addition on the stretching vibration of the hydroxyl group, and the characteristic absorption peak of the carbon-carbon double bond at 1630 cm -1 of Masson's pine completely disappears after the addition, and the characteristic absorption peak of the carbon-carbon double bond at 1698 cm -1The characteristic peak of carboxyl group at 1698 cm Figure 6 The characteristic peaks of pre-polymer at 729 and 695 cm -1 were obviously weakened, while the characteristic peak of hydroxyl group at 3398 cm -1 of trimethylolpropane was not only red-shifted to 3443 cm -1 but also obviously weakened in intensity, and the characteristic peak of carboxyl group at 1698 cm -1 of rosin-based adduct was obviously disappeared, while the characteristic peak of ester carbonyl at 1735 cm -1 and the characteristic peak of ester ether bond at 1178 cm -1 were obviously enhanced, which indicated that the esterification reaction between the pre-polymer containing hydroxyl group and the rosin-based adduct containing carboxyl group was obviously occurred. In summary, the rosin-based waterborne anticorrosive coating resin was successfully synthesized by esterification of the pre-polymer prepared by alcoholysis of soybean oil and polyhydric alcohol with long-chain dibasic acid, and then addition of fumaric acid.

[0109] Since the structures and characterization of the resins of other examples and comparative examples are similar to those of the product of Example 1, they are not described here.

[0110] According to the test results in Table 3, the rosin-based waterborne anticorrosive coating resin was successfully synthesized according to the method of the present application.

[0111] In addition, 6% of water-based drier was added to the rosin-based waterborne anticorrosive coating resins prepared in the examples and comparative examples of the present application, and a film with a certain thickness was coated on a tinplate substrate by using a 60 μm wire bar coater. The sample was cured after coating at a temperature of about 25°C and a relative humidity of about 65%, and the periphery of the sample used for coating immersion test was edge-sealed by using a mixture of 1:1 paraffin and rosin. The related coating films were obtained by using the above steps, and their performance indicators were tested. The related test results are shown in Table 4.

[0112] Table 4

[0113]

[0114]

[0115] The prepared rosin-based waterborne anticorrosive coating resins of the examples and the comparative examples were coated, cured and packaged, and it was found that the coating film prepared by the examples had excellent performance, the surface was smooth and flat, had excellent acid and alkali resistance and salt water resistance, had good gloss (more than 110), the surface dry and real dry time were short (the surface dry time was not more than 150 min, the real dry time was not more than 598 min), the coating film hardness was moderate (B to H), the adhesion was strong (1 to 0 level), the storage stability was good (stable without delamination at room temperature for 6 months) and the like.

[0116] The coating film prepared in Comparative Example 1 appeared to be difficult to dry, whitening and blistering in acid and alkali resistance tests, emulsion delamination and low gloss (46.9) due to the addition of the drying oil in step (1), and the hardness (3B) and adhesion (3 level) also significantly decreased compared with Examples 1-8.

[0117] The coating film prepared in Comparative Example 2 appeared to have long surface dry time (355 min) and real dry time (1377 min), low gloss (75.6), hardness (2B) and adhesion (2 level) due to the addition of the short chain (carbon atom number <8) saturated dibasic acid (adipic acid) in step (2), and the above-mentioned properties obviously decreased compared with Examples 1-8.

[0118] The coating film prepared in Comparative Example 3 appeared to have long surface dry time (396 min) and real dry time (1623 min), low gloss (67.6), hardness (2B) and adhesion (2 level) due to the addition of the short chain (carbon atom number <8) saturated dibasic acid (succinic acid) in step (2), and the above-mentioned properties obviously decreased compared with Examples 1-8.

[0119] The coating film prepared in Comparative Example 4 appeared to have long surface dry time (243 min) and real dry time (1187 min), whitening and blistering in water resistance, acid and alkali resistance and salt water resistance, delamination at room temperature and the like due to the excessive addition of the unsaturated acid in step (3), and the gloss (87.8) and adhesion (2 level) also obviously decreased compared with Examples 1-8.

[0120] Finally, it should be noted that the above content is only used to illustrate the technical solutions of the present application, and is not a limitation on the protection scope of the present application. Simple modifications or equivalent replacements of the technical solutions of the present application made by those skilled in the art do not deviate from the essence and scope of the technical solutions of the present application.

Claims

1. A process for the preparation of a rosin-based waterborne anticorrosive coating resin, characterized by: The preparation method comprises the following steps: (1) alcoholysis of a plant oil to obtain an alcoholysis product; The plant oil is one or more of dry plant oils and semi-dry plant oils; The dry plant oil is one or more of tung oil, flaxseed oil, hempseed oil and balsa wood oil; and the semi-dry plant oil is one or more of soybean oil, cottonseed oil and sunflower seed oil; (2) adding a saturated dibasic acid with 8 or more carbon atoms to the alcoholysis product obtained in step (1) to perform esterification reaction and obtain a prepolymer; (3) addition of rosin with an unsaturated acid and / or an unsaturated acid anhydride to obtain a rosin-based adduct; The amount of the unsaturated acid and / or the unsaturated acid anhydride is 19.2-31.5% of the mass of the rosin; (4) reaction of the rosin-based adduct in step (3) with the prepolymer obtained in step (2) to obtain a water-based resin precursor; (5) amination of the water-based resin precursor in step (4) to form a salt to obtain a rosin-based water-based anticorrosive coating resin.

2. The method of claim 1, wherein: The alcoholysis in step (1) comprises the step of adding an alcohol and a catalyst to the plant oil.

3. The method of claim 2, wherein: The alcohol is one or more of polyhydric alcohols; and the catalyst is one or more of inorganic bases.

4. The method of claim 1, wherein: The amination to form a salt in step (5) comprises the step of adding an organic base to the water-based resin precursor; and the organic base is one or more of organic amines.

5. The method of claim 3, wherein: The polyhydric alcohol is one or more of glycerol, trimethylolpropane and quaternary alcohol, or is one or more of glycerol, trimethylolpropane and pentaerythritol mixed with one or more of ethylene glycol, diethylene glycol, triethylene glycol and neopentyl glycol.

6. The rosin-based water-based anticorrosive coating resin prepared by the preparation method in any one of claims 1-5.

7. Application of the rosin-based water-based anticorrosive coating resin prepared by the preparation method in any one of claims 1-5 in a water-based anticorrosive coating.

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