Quick-drying high-corrosion-resistance alkyd resin, preparation method thereof and coating composition

Abstract

The embodiment of the invention provides quick-drying high-corrosion-resistance alkyd resin, a preparation method thereof and a coating composition. The quick-drying high-corrosion-resistance alkyd resin comprises the following components in parts by weight: 25-35 parts of C12 bio-based vegetable oil waste; 10 to 25 parts of terephthalic acid; 10-20 parts of a unit acid; 10 to 20 parts of polyol; 0.003 to 0.005 part of an alcoholysis catalyst; 1.6 to 2.0 parts of maleic anhydride; and 5-8 parts of abietic acid. According to the quick-drying high-corrosion-resistance alkyd resin, the preparation method thereof and the coating composition provided by the embodiment of the invention, through the proportion and synergistic effect of the components, the inherent defects of low drying rate, poor alkali resistance and high viscosity of the traditional alkyd resin are successfully overcome. And the quick-drying and high-corrosion-resistant performance breakthrough is achieved, and the quick-drying and high-corrosion-resistant coating has wide application prospects and is particularly suitable for the quick anti-corrosion coating requirements of metal surfaces of automobiles, mechanical parts and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of paint raw materials, and particularly relates to a fast-drying high-corrosion-resistant alkyd resin, a preparation method thereof and a paint composition. BACKGROUND

[0002] As the core matrix material of the paint industry, the traditional synthesis path of alkyd resin has long relied on long-chain (C16 / C18) plant oils such as soybean oil and flaxseed oil or petroleum-based chemical raw materials. Such raw material systems face multiple bottlenecks in industrial application: on the one hand, plant oil resources are subject to planting cycle and regional limitations, and there is a risk of supply chain fluctuations; on the other hand, petroleum-based raw materials are subject to carbon emission constraints and energy transformation pressure. At the raw material structure level, the introduction of long-chain fatty acid units endows the resin with excellent flexibility, but the high molecular chain segment movement energy barrier leads to slow drying rate of the coating film, insufficient alkali resistance and high system viscosity, which is difficult to meet the stringent requirements of modern industrial anticorrosion coating for fast curing, weather resistance and construction efficiency.

[0003] Although some progress has been made in the bio-based alternative path in recent years, existing research has focused on directly using primary plant oils (such as rapeseed oil and palm oil) as fatty acid donors. Such a solution can reduce carbon footprint, but it is difficult to avoid the problem of resource competition with food, and its molecular structure is still difficult to break through the performance ceiling of traditional alkyd resin due to the chain length distribution characteristics of natural oils. Therefore, developing a new bio-based raw material system to break through the inherent limitations of long-chain fatty acids through molecular structure design has become a key breakthrough for the iterative and environmentally friendly transformation of alkyd resin technology. SUMMARY

[0004] Therefore, the embodiments of the present application provide a fast-drying high-corrosion-resistant alkyd resin, a preparation method thereof and a paint composition to solve the technical problem that the existing traditional alkyd resin is difficult to balance between drying speed and corrosion resistance.

[0005] In a first aspect, the embodiments of the present application provide a fast-drying high-corrosion-resistant alkyd resin, which comprises the following components by weight: 25-35 parts of C12 bio-based plant oil waste; 10-25 parts of terephthalic acid; 10-20 parts of unit acid; 10-20 parts of polyol; 0.003-0.005 parts of alcoholysis catalyst; 1.6-2.0 parts of maleic anhydride; 5-8 parts of rosin acid.

[0006] In some embodiments, the C12 bio-based plant oil waste is coconut oil production waste, wherein the content of lauric acid is not less than 92%.

[0007] In some embodiments, the unit acid comprises at least one of hydrogenated rosin, benzoic acid, benzoic acid, coconut oil acid, soybean oil acid, linseed oil acid, ricin oil acid, and tall oil acid.

[0008] In some embodiments, the polyol comprises at least one of glycerol, trimethylolpropane, neopentyl glycol, pentaerythritol, ethylene glycol, propylene glycol, and diethylene glycol.

[0009] In some embodiments, the polyol comprises at least two of glycerol, trimethylolpropane, neopentyl glycol, and pentaerythritol, and the weight ratio of the two polyols is 1: (1-3).

[0010] In some embodiments, the weight ratio of the maleic anhydride to the rosin acid is 1: (2.5-4).

[0011] In a second aspect, the embodiments of the present application provide a preparation method of the fast-drying high corrosion-resistant alkyd resin as described in the first aspect, comprising the following steps: Mixing the C12 bio-based plant oil waste, the polyol, and the alcoholysis catalyst, and reacting under first conditions to obtain an alcoholysis product; Adding the terephthalic acid, the maleic anhydride, the unit acid, and the rosin acid to the alcoholysis product, and reacting under second conditions to obtain an esterification product; Post-treating the esterification product to obtain the fast-drying high corrosion-resistant alkyd resin.

[0012] In some embodiments, the first conditions comprise: The reaction temperature is 240-245°C, and the reaction time is 60-90 min.

[0013] In some embodiments, before adding the terephthalic acid, the maleic anhydride, the unit acid, and the rosin acid to the alcoholysis product, the alcoholysis product is cooled to 150-155°C.

[0014] In some embodiments, the second conditions comprise: The reaction temperature is 240-250°C, and the reaction time is 150-200 min; Adding a reflux water-carrying agent to the reaction system; The reaction is terminated when the acid value in the reaction system reaches below 20 mgKOH / g and the viscosity reaches 35-40 seconds (25°C, resin: xylene = 10:4).

[0015] Thirdly, embodiments of this application also provide a coating composition comprising the fast-drying corrosion-resistant alkyd resin described in the first aspect or the fast-drying corrosion-resistant alkyd resin prepared by the preparation method described in the second aspect, and the coating composition is used to prepare metal anti-rust paint, marine paint, industrial machinery topcoat or wood paint.

[0016] The fast-drying, highly corrosion-resistant alkyd resin, its preparation method, and coating composition provided in this application successfully overcome the inherent defects of traditional alkyd resins, such as low drying rate, poor alkali resistance, and high viscosity, through the synergistic effect of the components. C12 bio-based vegetable oil waste, as a key raw material, avoids the sustainability issues of traditional vegetable oils and significantly improves drying speed and hardness through its short-chain structure. The synergistic effect of terephthalic acid and maleic anhydride greatly enhances corrosion resistance, while the combination of mono-acid and rosin acid ensures the flexibility and adhesion of the paint film. This formulation aligns with the industry's trend towards environmental protection and high performance. Through bio-based raw material substitution and molecular structure design, it achieves a breakthrough in fast drying and high corrosion resistance, possessing broad application prospects, particularly suitable for the rapid anti-corrosion coating needs of metal surfaces such as automotive and mechanical parts. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic flowchart of the preparation method of the fast-drying, highly corrosion-resistant alkyd resin provided in the embodiments of this application. Detailed Implementation

[0019] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that the embodiments of this application can also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted so as not to obscure the description of the embodiments of this application with unnecessary detail.

[0020] It should also be understood that the term "and / or" as used in the specification of embodiments of this application and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0021] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0022] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0023] Furthermore, in the description of the embodiments and the appended claims of this application, the terms "first," "second," "third," etc., are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance.

[0024] In the description of embodiments in this application, references to "some embodiments" or "some embodiments" mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in some embodiments," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiments, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized. "A plurality" refers to two or more.

[0025] In a first aspect, embodiments of this application provide a fast-drying, highly corrosion-resistant alkyd resin, comprising the following components in parts by weight: 25-35 parts of C12 bio-based vegetable oil waste; 10-25 parts of terephthalic acid; 10-20 parts of monoacid; 10-20 parts of polyol; Alcohololysis catalyst: 0.003~0.005 parts; Maleic anhydride 1.6~2.0 parts; Rosin acid 5-8 parts.

[0026] This application's embodiments utilize C12 bio-based vegetable oil waste to replace traditional long-chain vegetable oils, significantly reducing oil content to a short oil content range. Combined with the rigid aromatic ring structure of terephthalic acid, this synergistically improves film hardness and drying rate. Maleic anhydride introduces unsaturated double bonds, forming a high-crosslinking density network with rosin acid, resulting in improved salt spray resistance and reduced water absorption. Precise proportions of monoacids and polyols control molecular weight distribution, balancing flexibility and application suitability (viscosity 35-40 seconds). The highly efficient catalytic action of the alcoholysis catalyst shortens the reaction cycle, simultaneously achieving low VOC emissions. The overall formulation avoids land disputes with food crops through bio-based raw material substitution, and its rigid-flexible structural design balances fast drying, corrosion resistance, and environmental friendliness, meeting the urgent needs of the automotive, marine, and other industrial sectors for high-performance, environmentally friendly coatings.

[0027] In some embodiments, the C12 bio-based vegetable oil waste is coconut oil production waste, wherein the lauric acid content is not less than 92%. Choosing coconut oil production waste as the C12 bio-based vegetable oil waste, with a lauric acid content ≥92%, has dual technical value. First, as a saturated medium-chain fatty acid, lauric acid's short-chain structure significantly enhances the activity of alcoholysis reaction, shortening the oil content to 25-35%, making the resin closer to a short-oil-content system, thereby accelerating the oxidative crosslinking of the coating film. Second, high-purity lauric acid (92%) can reduce impurity interference, ensure molecular chain segment regularity, and improve the resin's thermal stability and alkali resistance.

[0028] In application, by using coconut oil production waste as C12 bio-based vegetable oil waste, the bio-based content is significantly increased. Coconut oil waste accounts for 25-35% of the total formulation, bringing the bio-based content to 30-35%, which meets the EU REACH regulations for bio-based material certification requirements. Replacing new raw materials with waste effectively reduces costs while decreasing the use of fossil fuels, achieving carbon reduction throughout the entire life cycle. The high reactivity and short-chain characteristics of lauric acid work synergistically to broaden the resin viscosity control window, effectively improving film hardness and salt spray resistance compared to traditional systems.

[0029] In some embodiments, the monoacid includes at least one selected from hydrogenated rosin, benzoic acid, cocooleic acid, soybean oil, linolenic acid, ricinoleic acid, and pine oleic acid. All of the above monoacids contain carboxyl functional groups and can undergo polycondensation with polyols and polyacids to adjust the resin acid value and ensure a balanced reactivity of the system.

[0030] This product encompasses saturated fatty acids (coconut oil acid), unsaturated fatty acids (linolenic acid), aromatic acids (benzoic acid), and modified resin acids (hydrogenated rosin). The crosslinking density, flexibility, and weather resistance of the resin can be controlled through the distribution of functional groups. Except for benzoic acid, the other unit acids are derived from vegetable oils or natural resin waste, meeting the design goal of high bio-based content. Preferably, the unit acid is hydrogenated rosin, which can improve crosslinking density and corrosion resistance. As a tricyclic diterpenoid resin acid, the rigid structure of hydrogenated rosin can synergistically form a highly crosslinked network with terephthalic acid and maleic anhydride, effectively improving the resin's salt spray resistance while reducing water absorption. Furthermore, rosin acid derivatives (such as hydrogenated rosin) have strong polarity, which can improve the interfacial bonding between the resin and the substrate, achieving an adhesion strength ≥3MPa; its crystal structure imparts high gloss to the paint film. Hydrogenated rosin exhibits excellent thermal stability, is not easily decomposed during high-temperature polycondensation reactions at 245℃, avoids the formation of by-products, and ensures the resin's color and transparency.

[0031] In some embodiments, the polyol includes at least one selected from glycerol, trimethylolpropane, neopentyl glycol, pentaerythritol, ethylene glycol, propylene glycol, and diethylene glycol. These polyols have a polyhydroxy structure, containing 2-4 hydroxyl groups, serving as the core reaction sites for alkyd resin synthesis. They form the main chain structure with polybasic and monobasic acids through esterification reactions. Polyols with different functionalities (diols, triols, tetraols) allow for precise control of the resin's crosslinking density. Except for some synthetic alcohols, most polyols (such as glycerol and trimethylolpropane) can be prepared from bio-based raw materials (such as vegetable oils and starch), meeting the design goal of high bio-based content. They can stably participate in the reaction under high-temperature alcoholysis conditions of 240-245°C, ensuring the controllability of the resin synthesis process.

[0032] In a preferred embodiment, the polyol used is pentaerythritol. Pentaerythritol is a tetrahydric alcohol, with each molecule providing four hydroxyl groups, significantly increasing the crosslinking density of the resin (forming a three-dimensional network synergistically with terephthalic acid and maleic anhydride), thus raising the thermogravimetric temperature and improving weather resistance (gloss retention >90% after UV aging) compared to traditional systems. Its branched structure avoids brittleness caused by excessive crosslinking, allowing the paint film to maintain high hardness while being suitable for coating substrates with complex morphologies. The rigid structure of pentaerythritol reduces inter-segment entanglement, allowing the resin viscosity at 25°C to be controlled at 35-40 seconds (resin:xylene = 10:4), matching the spraying process requirements of fast-drying coatings.

[0033] In some embodiments, the polyol includes at least two of glycerol, trimethylolpropane, neopentyl glycol, and pentaerythritol, with a weight ratio of 1:(1-3). Specifically, the polyol includes trimethylolpropane and neopentyl glycol, with a mass ratio of 5:2. The triol provides moderate crosslinking, with each molecule contributing three hydroxyl groups to form a three-dimensional network structure, improving resin hardness and temperature resistance. The diol introduces flexible segments, and the isopropyl side chain reduces inter-segmental forces, resulting in an elongation at break >80%, balancing brittleness and flexibility. A higher proportion of triol ensures film hardness, while a higher proportion of diol alleviates brittleness and prevents film cracking. This is suitable for fast-drying coating of substrates with complex morphologies (such as automotive parts), balancing hardness and flexibility. In other embodiments, the polyol includes trimethylolpropane and pentaerythritol, with a mass ratio of 1:1. Triols and tetraols work synergistically, with triols providing moderate crosslinking and tetraols providing high crosslinking, forming a rigid-flexible three-dimensional network. In some other embodiments, the polyols include glycerol and pentaerythritol in a 2:1 mass ratio. The low-cost advantage of glycerol synergizes with the high crosslinking density of tetraols. In other embodiments, the polyols include trimethylolpropane and pentaerythritol in a 3:2 mass ratio. Triols dominate the crosslinking structure, providing a more continuous three-dimensional network at 60%, reducing the over-crosslinking brittleness that might be introduced by the higher proportion of tetraols. Localized reinforcement by tetraols creates highly crosslinked regions at critical locations (such as the paint film surface), improving chemical resistance. A higher proportion of triols mitigates the brittleness of tetraols, resulting in an elongation at break >70%. The gradient crosslinking design of triols and tetraols reduces the risk of gelation and ensures stable resin viscosity (35-40 seconds).

[0034] In some embodiments, the weight ratio of maleic anhydride to rosin acid is 1:(2.5~4). This ratio range has the following advantages: the amount of rosin acid is ≥2.5 times that of maleic anhydride, ensuring that the rosin acid provides sufficient acidic groups, improving the adhesion and gloss of the paint film, and avoiding brittleness of the paint film due to excessive maleic anhydride. The amount of rosin acid is ≤4 times that of maleic anhydride, preventing yellowing of the paint film, decreased drying speed, or increased viscosity caused by excessive rosin acid, which affects the application performance. This range balances crosslinking density and adhesion / gloss, avoiding performance imbalance. In specific embodiments, the weight ratio of maleic anhydride to rosin acid can be any value within the range of 1:(2.5~4), such as 1:2.5, 1:3, 1:3.5, 1:4, etc.

[0035] The fast-drying, high-corrosion-resistant alkyd resin provided in this application embodiment is the first to use coconut oil industrial waste as the main raw material for alkyd resin, which makes the bio-based content of the product reach 30%-35%, reduces the raw material cost by more than 20%, and achieves the dual benefits of "turning waste into treasure" and carbon emission reduction.

[0036] Leveraging the small molecular weight and high mobility of C12 short-chain fatty acids, the viscosity of the resin bulk is significantly reduced, improving application solids content and leveling properties. The synergistic enhancement mechanism of maleic anhydride and rosin acid provides additional active crosslinking sites, while the rigid phenanthrene ring structure of rosin acid imparts segment rigidity. Together, they form a dense and robust interpenetrating network in the cured film. Highly saturated raw materials fundamentally reduce oxidative degradation sites, significantly improving the coating's resistance to UV aging and yellowing.

[0037] Secondly, such as Figure 1 As shown in the embodiments of this application, a method for preparing a fast-drying, highly corrosion-resistant alkyd resin as described in the first aspect is provided, comprising the following steps: S10. Mix C12 bio-based vegetable oil waste, polyol and alcoholysis catalyst, and react under the first condition to obtain alcoholysis product; S20. Terephthalic acid, maleic anhydride, monoacid and rosin acid are added to the alcoholysis product, and the reaction is carried out under the second condition to obtain the esterification product. S30. The esterification product is post-treated to obtain a fast-drying, highly corrosion-resistant alkyd resin.

[0038] This preparation method achieves a breakthrough in fast drying, high corrosion resistance, and high environmental friendliness through a precise and synergistic three-step process of alcoholysis-esterification-post-treatment. The synergistic cross-linking of the C12 short-chain structure of S10 and the maleic anhydride of S20 reduces the drying time to ≤1.5 hours. In S20, terephthalic acid (rigid) and maleic anhydride (cross-linking point) construct a highly dense network, significantly improving salt spray resistance. The use of C12 waste (coconut oil) ensures a bio-based content of 30-35%, effectively reducing raw material costs. The sequential design of S10-S20 avoids side reactions, and the precise viscosity control of S30 (35-40 seconds) guarantees consistency in large-scale production. In summary, this method not only solves the industry pain points of slow drying and poor corrosion resistance of traditional alkyd resins but also achieves a dual breakthrough in technology and environmental protection through a waste-to-resource utilization path (coconut oil waste → resin), providing a sustainable and high-performance solution for industrial anti-corrosion coatings.

[0039] In some embodiments, S10 is an alcoholysis step, in which triglycerides in C12 bio-based vegetable oil waste (such as coconut oil waste) are decomposed into monoglycerides and free fatty acids through an alcoholysis reaction, while simultaneously forming an active intermediate with a polyol (such as pentaerythritol). This step is crucial for the directional construction of short-chain structures, laying the foundation for subsequent rapid drying; the alcoholysis catalyst accelerates the reaction, ensuring efficient completion of alcoholysis (transparent methanol tolerance test), and avoiding slow drying problems caused by long-chain structure residues. Vegetable oil waste, polyol, and catalyst are added simultaneously to prevent acidic components (such as maleic anhydride) from prematurely participating in the reaction and causing side reactions. This sequence ensures the purity of alcoholysis, providing a highly active intermediate for esterification in S20.

[0040] In some embodiments, S20 is an esterification polycondensation step, carried out at 245°C, achieving performance breakthroughs through precise molecular structure design. Terephthalic acid provides a rigid aromatic ring, enhancing corrosion resistance; maleic anhydride and rosin acid form a high-crosslinking density network; the monoacid adjusts the acid value, and rosin acid strengthens adhesion. The alcoholysis product serves as the base substrate, followed by the addition of acid components (terephthalic acid, maleic anhydride, etc.) to avoid direct reaction between polyols and acids, which could lead to uncontrolled molecular weight. This sequence precisely controls the polycondensation process, preventing localized overheating or gelation.

[0041] In some embodiments, step S30 is a post-processing step. This involves diluting, filtering, and desolventizing the esterification product to optimize its workability.

[0042] In some embodiments, the first conditions include: a reaction temperature of 240℃~245℃ and a reaction time of 60min~90min. Setting the temperature within this range allows for precise matching of the reaction characteristics of C12 short-chain fatty acids. C12 bio-based vegetable oil waste (such as coconut oil waste, with lauric acid ≥92%) has high reactivity due to its short-chain structure, but excessively low temperatures lead to insufficient alcoholysis rates and prolonged reaction times; excessively high temperatures easily cause fatty acid oxidation, coking, or catalyst deactivation (such as lithium hydroxide decomposition), resulting in a darker product color or abnormal viscosity. 240℃~245℃ is the optimal window for C12 fatty acid alcoholysis, ensuring reaction initiation efficiency and maximizing the reactivity of short-chain fatty acids while avoiding side reactions. This ensures high transparency (meeting methanol tolerance test standards) and stable color of the obtained alcoholysis product, providing a pure substrate for subsequent esterification. Specifically, the reaction temperature can be 240℃, 241℃, 242℃, 243℃, 244℃, 245℃, etc. The reaction time can be 60 min, 62 min, 65 min, 68 min, 70 min, 72 min, 75 min, 78 min, 80 min, 85 min, 90 min, etc.

[0043] In some embodiments, before adding terephthalic acid, maleic anhydride, monoacid, and rosin acid to the alcoholysis product, the alcoholysis product is cooled to 150°C to 155°C. This cooling step ensures that the acid components (maleic anhydride and terephthalic acid) are fully dissolved and mixed at a low temperature, avoiding molecular chain breakage or uneven crosslinking caused by rapid reaction at high temperatures; it also provides a controllable starting point for subsequent gradual heating to 245°C, enabling the resin to achieve a balance between high crosslinking density and low viscosity during the esterification stage.

[0044] In applications, directly adding acidic components such as terephthalic acid and maleic anhydride to the alcoholysis products (240℃~245℃) can lead to the following risks due to high temperatures: maleic anhydride dehydration and deactivation (maleic anhydride is prone to dehydration to form maleic anhydride at temperatures above 150℃, resulting in reduced crosslinking points and decreased corrosion resistance); localized overheating and coking (the acidic components release heat violently at high temperatures, causing localized temperature spikes, leading to a darkening of the resin color and a sudden increase in viscosity, affecting its workability). Cooling to 150℃~155℃ optimizes the process. This temperature range is the stability window for maleic anhydride, ensuring complete retention of unsaturated double bonds, providing a foundation for subsequent high crosslinking density; it also reduces the risk of oxidation of residual fatty acids in the alcoholysis products, preventing yellowing of the paint film.

[0045] In some embodiments, the second conditions include: a reaction temperature of 240°C to 250°C and a reaction time of 150 min to 200 min; Add a reflux water-carrying agent to the reaction system; The reaction was terminated when the acid value and viscosity of the reaction system were measured and the acid value reached below 20 mg KOH / g and the viscosity reached 35-40 seconds (25℃, resin: xylene = 10:4).

[0046] This temperature design is not simply a continuation of the high temperature of S10, but a scientific optimization tailored to the specific characteristics of the esterification polycondensation reaction. This temperature range avoids side reactions. Below 240℃, the esterification rate of terephthalic acid and maleic anhydride is too slow, leading to incomplete reactions; above 250℃, it triggers dehydration of maleic anhydride and charring of rosin acid. In conjunction with the S10 cooling step, S10 ends at 240~245℃, while S20 requires a temperature increase from 150~155℃ to 240~250℃. This stepwise temperature increase ensures uniform dispersion of the acid components (terephthalic acid and maleic anhydride) at low temperatures, avoiding localized overheating. The reaction time (150min~200min) matches the molecular weight growth curve, satisfying basic esterification and completing polycondensation. A water-carrying agent (xylene is used in this embodiment) is refluxed. The esterification reaction produces water, which inhibits the reaction. Xylene continuously removes water through azeotropic distillation, shifting the equilibrium towards the product and improving the reaction conversion rate.

[0047] Acid value ≤20mgKOH / g ensures extremely low free acid content and avoids poor alkali resistance of the paint film. Viscosity 35~40 seconds (25°C, resin:xylene=10:4), 35 seconds: moderate molecular weight, good paint film flexibility; 40 seconds: avoids excessive polymerization leading to sagging.

[0048] The method for preparing fast-drying, highly corrosion-resistant alkyd resin provided in this application achieves precise control of acid value and viscosity through alcoholysis endpoint monitoring and xylene reflux esterification, ensuring high batch-to-batch stability of the product. By precisely designing the maleic anhydride dosage and feeding sequence, gelation is effectively avoided while increasing crosslinking density, significantly improving production safety and yield.

[0049] The resulting resin possesses excellent overall properties: Fast drying: Surface drying time ≤ 5 hours, complete drying time ≤ 24 hours, far exceeding traditional long-oil alkyd resins. Superior corrosion resistance: Dense coating with excellent resistance to salt water (no abnormalities after 48 hours) and salt spray (≥ 480 hours), effectively blocking the penetration of corrosive media. Balanced environmental protection and economic benefits: VOC content reduced by 15%~20%, combining high performance and green attributes, resulting in strong market competitiveness.

[0050] Thirdly, embodiments of this application also provide a coating composition comprising the fast-drying corrosion-resistant alkyd resin described in the first aspect or the fast-drying corrosion-resistant alkyd resin prepared by the preparation method described in the second aspect, and the coating composition is used to prepare metal anti-rust paint, marine paint, industrial machinery topcoat or wood paint.

[0051] The coating composition provided by this invention is based on a fast-drying, highly corrosion-resistant alkyd resin. Through the synergistic reaction of C12 bio-based vegetable oil waste with polybasic acids such as terephthalic acid and maleic anhydride, a molecular structure combining short-chain fatty acids and rigid aromatic rings is constructed, significantly improving the corrosion resistance and crosslinking density of the paint film. This resin system exhibits excellent barrier properties in metal anti-rust paints, effectively resisting salt spray corrosion; in marine paints, it possesses good weather resistance and resistance to marine environmental corrosion; when used as topcoat for industrial machinery, its rapid drying characteristics are suitable for efficient production processes, while its low viscosity design ensures smooth application; when applied to wood coatings, the paint film has uniform gloss and strong adhesion. By introducing bio-based raw materials to replace traditional petrochemical resources, not only are carbon emissions reduced, but the problem of competing with food crops for land is also avoided, achieving a dual optimization of environmental protection and performance. This provides an economical and sustainable solution for industrial corrosion protection, high-end equipment, and home coating fields.

[0052] Example Example 1 This application provides a fast-drying, highly corrosion-resistant alkyd resin and its preparation method, wherein the preparation method includes the following steps: S10. Add 30 kg of C12 bio-based vegetable oil waste (lauric acid content 95%), 15 kg of pentaerythritol and 0.004 kg of lithium hydroxide to the reactor and mix. Heat to 240°C and carry out alcoholysis reaction for 85 minutes to obtain alcoholysis product. Cool down to 150°C. S20. Add 18 kg of terephthalic acid, 1.8 kg of maleic anhydride, 12 kg of hydrogenated rosin and 6 kg of rosin acid to the alcoholysis product, gradually raise the temperature to 245°C, add an appropriate amount of xylene and reflux for 180 minutes to obtain the esterification product; the reaction is stopped when the acid value of the reaction solution drops to 19 mg KOH / g and the viscosity reaches 38 seconds (test conditions are the same as above).

[0053] S30, cool to 165℃, transfer the esterification product to a dilution reactor containing 200# solvent oil, and filter to obtain a fast-drying, highly corrosion-resistant alkyd resin with a solid content of 70.2%.

[0054] Example 2 The procedure is basically the same as in Example 1, except that the polyol system is adjusted. 28 kg of C12 bio-based vegetable oil waste (95% lauric acid content), 10 kg of trimethylolpropane and 4 kg of neopentyl glycol are used. Other steps and conditions are the same as in Example 1.

[0055] Example 3 This application provides a fast-drying, highly corrosion-resistant alkyd resin and its preparation method, wherein the preparation method includes the following steps: S10. Add 28 kg of C12 bio-based vegetable oil waste (lauric acid content 95%), 7.5 kg of trimethylolpropane + 7.5 kg of pentaerythritol and 0.004 kg of lithium hydroxide to the reactor and mix. Heat to 242℃ for alcoholysis reaction for 75 minutes to obtain alcoholysis product. Continue until methanol tolerance meets the standard, and then cool down to 150℃. S20. Add 22 kg of terephthalic acid, 1.8 kg of maleic anhydride, 12 kg of hydrogenated rosin and 6 kg of rosin acid to the alcoholysis product, gradually raise the temperature to 245°C, add an appropriate amount of xylene and reflux for 190 minutes to obtain the esterification product; the reaction is stopped when the acid value of the reaction solution drops to 18 mg KOH / g and the viscosity reaches 38 seconds (test conditions are the same as above).

[0056] S30, cool to 165℃, transfer the esterification product to a dilution reactor containing 200# solvent oil, and after filtration, obtain a fast-drying, highly corrosion-resistant alkyd resin with a solid content of 71.5%.

[0057] Example 4 This application provides a fast-drying, highly corrosion-resistant alkyd resin and its preparation method, wherein the preparation method includes the following steps: S10. Add 35kg of C12 bio-based vegetable oil waste (lauric acid content 95%), 12kg of glycerol + 6kg of neopentyl glycol and 0.003kg of lithium hydroxide to the reaction vessel and mix. Heat to 240℃ and carry out alcoholysis reaction for 90 minutes to obtain alcoholysis product. Continue until the methanol tolerance reaches the standard, and then cool down to 150℃. S20. Add 15 kg of terephthalic acid, 1.6 kg of maleic anhydride, 10 kg of benzoic acid and 5 kg of rosin acid to the alcoholysis product, gradually raise the temperature to 245°C, add an appropriate amount of xylene and reflux for 160 minutes to obtain the esterification product; the reaction is stopped when the acid value of the reaction solution drops to 19 mg KOH / g and the viscosity reaches 38 seconds.

[0058] S30, cool to 165℃, transfer the esterification product to a dilution reactor containing 200# solvent oil, and after filtration, obtain a fast-drying, highly corrosion-resistant alkyd resin with a solid content of 68.8%.

[0059] Example 5 This application provides a fast-drying, highly corrosion-resistant alkyd resin and its preparation method, wherein the preparation method includes the following steps: S10. Add 25kg of C12 bio-based vegetable oil waste (lauric acid content 95%), 7.2kg of trimethylolpropane + 4.8kg of pentaerythritol and 0.005kg of lithium hydroxide to the reactor and mix. Heat to 245℃ and carry out alcoholysis reaction for 60 minutes to obtain alcoholysis product. Continue until methanol tolerance reaches the standard, and then cool down to 150℃. S20. Add 25 kg of terephthalic acid, 2 kg of maleic anhydride, 10 kg of hydrogenated rosin + 10 kg of benzoic acid and 8 kg of rosin acid to the alcoholysis product. Increase the temperature in two stages (150℃ to 200℃ and then to 245℃). Add an appropriate amount of xylene and reflux for 200 minutes to obtain the esterification product. The reaction is stopped when the acid value of the reaction solution drops to 17 mg KOH / g and the viscosity reaches 38 seconds (test conditions are the same as above).

[0060] S30, cool to 165℃, use 200# solvent oil and propylene glycol methyl ether acetate mixed solvent (4:1), filter to obtain fast-drying high corrosion resistant alkyd resin.

[0061] Performance testing The resins obtained in Examples 1 to 4 were subjected to surface drying time and complete drying time tests. The resins obtained in Examples 1, 3, and 5 were subjected to salt spray resistance tests. The resin obtained in Example 3 was subjected to coating pencil hardness and salt water resistance tests. The resin obtained in Example 4 was subjected to viscosity determination (test standard: GB / T1723-93) and bio-based content determination (test standard: ASTM D6866). The resin obtained in Example 5 was subjected to crosslinking density test (test standard: ASTM D3681), yellowing index test (test standard: ASTM D2244), and VOC content determination (test standard: GB18581-2020).

[0062] 1. Surface drying time test: Test standard GB / T1728-2020, operation steps: ① Apply resin film evenly to a standard steel plate (200×100×0.2mm); ② Let it stand in a constant temperature and humidity chamber at 25±2℃ and 60±5% humidity; ③ Gently touch the surface of the coating with a lint-free cotton ball (25mm in diameter), and use the absence of any adhering material as the judgment standard; ④ Record the time from coating to complete surface drying (cotton ball does not stick to the paint).

[0063] 2. Drying time test: Test standard GB / T1728-2020, operation steps: ① Prepare the coating film as in the surface drying test; ② After standing in the same environment until surface dry, continue the test; ③ Use a 2H pencil to scratch the coating film at a 45° angle and with a force of 500g. If there is no paint film peeling or scratches, it is considered dry; ④ Record the time from coating to reaching the dry standard.

[0064] 3. Salt spray resistance test: Test standard GB / T1771-2007, operating procedures: ① After the coated steel plate (200×100×0.2mm) has been surface-dried / fully dried, place it in the salt spray chamber; ② Salt water concentration: 5% NaCl (mass fraction); ③ Spraying conditions: 35±2℃, continuous spraying, spray volume 1~2mL / 80cm 2 • h; ④ Judgment criteria: 500 hours: no blistering, no rust (assessed according to ISO4628); >500 hours: the paint film remains intact, with only slight discoloration.

[0065] 4. Pencil Hardness Test (Determination of Paint Film Scratch Resistance), Test Standard GB / T6739-2006, Operating Procedures: ① Coating Preparation: Apply resin coating evenly to a standard tinplate (150×75×0.2mm), and allow it to cure after surface drying and complete drying; ② Test Tool: Use pencils ranging from HB to 9H (hardness increasing), with the pencil lead sharpened to a cylindrical shape (2mm in diameter), and clamped in a pencil hardness tester (45° angle, 500g pressure); ③ Test Procedure: Starting with the softest pencil (HB), scratch the coating film at a speed of 1cm / s; Judgment Criterion: When the pencil scratch does not damage the paint film (no paint film peeling or scratches), the next higher hardness level is the pencil hardness of that paint film. ④ Result Representation: If scratching up to a 2H pencil causes no damage, the hardness is 2H (Industry Standard: ≥H is excellent, ≥2H is high hardness).

[0066] 5. Salt water resistance test, test standard GB / T1733-2019, operation steps: ① Coating preparation: same as pencil hardness test, coating thickness controlled at 30~40μm; ② Test conditions: Salt water preparation: 5% NaCl solution (mass fraction, prepared with distilled water); Immersion environment: 35±2℃ constant temperature water bath, continuous immersion for 24 hours; ③ Judgment criteria: no blistering, no loss of gloss, no rust → pass (≥24h); blistering area ≤5% → excellent (≥48h); blistering area >5% → unqualified.

[0067] Test Results The resin coating obtained in Example 1 had a surface dry time of 4.5 hours, a complete dry time of 22 hours, and a salt spray resistance exceeding 500 hours. The resin obtained in Example 2 had a viscosity approximately 15% lower than that of Example 1, and its drying time was further shortened to a surface dry time of 4 hours and a complete dry time of 20 hours, exhibiting superior application flowability and curing efficiency. The resin coating obtained in Example 3 had a surface dry time of 4.2 hours, a complete dry time of 21 hours, a pencil hardness of 2H, salt spray resistance of ≥520 hours, and salt water resistance with no bubbling after 72 hours. The resin coating obtained in Example 4 had a surface dry time of 3.8 hours, a complete dry time of 18 hours, a viscosity of 14500 cP·s at 25℃, and a bio-based content of 35%. The crosslinking density of the resin obtained in Example 5 was 1.8 × 10⁻⁶. 3 mol / m 3 Salt spray resistance ≥550 hours; yellowing index: 1.2 (50% lower than traditional resin); VOC content ≤320g / L.

[0068] In summary, the resin obtained in Example 3 has high hardness and long-lasting corrosion resistance, making it more suitable for coating heavy machinery and marine platforms; the resin obtained in Example 4 has fast drying and is economical, making it more suitable for rapid coating of engineering machinery and steel structures; and the resin obtained in Example 5 has ultra-high crosslinking and weather resistance, making it more suitable for high-end outdoor equipment and automotive primers.

[0069] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0070] The above-described embodiments are only used to illustrate the technical solutions of the embodiments of this application, and are not intended to limit them. Although the embodiments of this application have been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of the embodiments of this application.

Claims

1. A fast-drying, highly corrosion-resistant alkyd resin, characterized in that, The components include the following parts by weight: 25-35 parts of C12 bio-based vegetable oil waste; 10-25 parts of terephthalic acid; 10-20 parts of monoacid; 10-20 parts of polyol; Alcohololysis catalyst: 0.003~0.005 parts; Maleic anhydride 1.6~2.0 parts; Rosin acid 5-8 parts.

2. The fast-drying, highly corrosion-resistant alkyd resin as described in claim 1, characterized in that, The C12 bio-based vegetable oil waste is coconut oil production waste, in which the lauric acid content is not less than 92%.

3. The fast-drying, highly corrosion-resistant alkyd resin as described in claim 1, characterized in that, The unit acid includes at least one of hydrogenated rosin, benzoic acid, coconut oil acid, soybean oil acid, linolenic acid, ricinoleic acid, and pine oil acid.

4. The fast-drying, highly corrosion-resistant alkyd resin as described in claim 1, characterized in that, The polyol includes at least one of glycerol, trimethylolpropane, neopentyl glycol, pentaerythritol, ethylene glycol, propylene glycol, and diethylene glycol.

5. The fast-drying, highly corrosion-resistant alkyd resin as described in claim 4, characterized in that, The polyols include at least two of glycerol, trimethylolpropane, neopentyl glycol, and pentaerythritol, and the weight ratio of the two polyols is 1:(1~3).

6. The fast-drying, highly corrosion-resistant alkyd resin as described in claim 1, characterized in that, The weight ratio of maleic anhydride to rosin acid is 1:(2.5~4).

7. A method for preparing a fast-drying, highly corrosion-resistant alkyd resin as described in any one of claims 1 to 6, characterized in that, Includes the following steps: The C12 bio-based vegetable oil waste, the polyol and the alcoholysis catalyst are mixed and reacted under the first condition to obtain the alcoholysis product. The terephthalic acid, maleic anhydride, monoacid, and rosin acid are added to the alcoholysis product, and the reaction is carried out under the second condition to obtain the esterification product. The esterification product is post-treated to obtain the fast-drying, highly corrosion-resistant alkyd resin.

8. The preparation method according to claim 7, characterized in that, The first condition includes: The reaction temperature is 240℃~245℃, and the reaction time is 60min~90min; and / or, Before adding the terephthalic acid, maleic anhydride, monoacid, and rosin acid to the alcoholysis product, the alcoholysis product is cooled to 150°C to 155°C.

9. The preparation method according to claim 7, characterized in that, The second condition includes: The reaction temperature is 240℃~250℃, and the reaction time is 150min~200min; Add a reflux water-carrying agent to the reaction system; The reaction was terminated when the acid value and viscosity of the reaction system were measured and the acid value reached below 20 mg KOH / g and the viscosity reached 35-40 seconds (25℃, resin: xylene = 10:4).

10. A coating composition, characterized in that, The coating composition comprises the fast-drying corrosion-resistant alkyd resin according to any one of claims 1 to 6 or the fast-drying corrosion-resistant alkyd resin prepared by the preparation method according to any one of claims 7 to 9, and the coating composition is used to prepare metal anti-rust paint, marine paint, industrial machinery topcoat or wood coating.

Images