A bio-based polyol and its preparation method and its application in heavy-duty anticorrosion coatings

Abstract

The present invention belongs to the field of bio-based polymer materials, and relates to a bio-based polyol, a preparation method thereof, and its application in heavy-duty anti-corrosion coatings. A carboxylic acid ring-opening reagent is mixed with a catalyst to obtain a second mixed liquid; the epoxy vegetable oil and the second mixed liquid are respectively pumped into a microfluidic reactor of a microfluidic reaction device at the same time to carry out a ring-opening reaction, and after the reaction is completed, the bio-based polyol is obtained by post-treatment. The present invention further copolymerizes the bio-based polyol with isocyanate, a chain extender and a functional filler to obtain a heavy-duty anti-corrosion coating with high hardness, wear resistance and chemical corrosion resistance, which is suitable for metal corrosion protection in harsh environments. The present invention realizes efficient and continuous production through microfluidic technology, breaks through the limitations of traditional processes on complex carboxylic acid systems, and significantly improves the coating performance and environmental protection.

Description

Technical Field

[0001] The invention belongs to the field of bio-based polymer materials and relates to a bio-based polyol and a preparation method thereof and application thereof in a heavy-duty anti-corrosion coating. Background Art

[0002] Heavy-duty anti-corrosion coatings are widely used in the field of industrial anti-corrosion, but their traditional formulations have long relied on petroleum-based polyols as core raw materials, which have problems such as non-renewable resources, high synthesis energy consumption, and poor biodegradability. Although bio-based polyols made from epoxidized vegetable oils can replace petroleum-based products, their preparation process still faces significant technical bottlenecks. At present, alcohol reagents (such as ethylene glycol and propylene glycol) are mostly used in ring-opening reactions. Such reagents have the following defects: (1) Low selectivity: alcohol ring opening easily causes excessive cross-linking of epoxy groups, resulting in a significant increase in product viscosity (traditional process viscosity ≥ 2000 mPa·s), making it difficult to evenly disperse in the coating system, affecting film-forming properties; (2) Single function: Simple alcohols cannot introduce key functional groups such as ester bonds, heterocycles, or double bonds in a directional manner, resulting in a single molecular chain structure of the polyol, which limits the mechanical properties (such as hardness, wear resistance) and chemical corrosion resistance of the coating.

[0003] In recent years, carboxylic acid ring-opening reagents have attracted attention because they can generate ester bonds in a directional manner and adjust the flexibility of molecular chains. However, although short-chain carboxylic acids (such as acetic acid and propionic acid) can improve some properties, the hydroxyl value of their products is still low (≤160 mg KOH / g), and the traditional intermittent reaction process has the following problems: (1) Uneven reaction: The temperature gradient leads to an increase in side reactions (such as self-polymerization of epoxy compounds), a wide molecular weight distribution of the product, and poor stability; (2) Low efficiency: The reaction time is as long as 3 to 4 hours, the energy consumption is high, and it is difficult to meet the needs of industrial continuous production.

[0004] Microfluidic reaction technology achieves efficient mass and heat transfer through micron-scale channels (diameter 0.5~2 mm), and can accurately control the reaction process. However, existing research focuses on single carboxylic acid systems (such as benzoic acid), and is not suitable for carboxylic acids containing complex functional groups (such as double bonds, heterocyclic or long-chain carboxylic acids). For example: double-bond carboxylic acids (such as 2-cyclohexenecarboxylic acid): Although they can enhance the flexibility of polyol segments, the double bonds are easily oxidized and broken in traditional intermittent processes, resulting in functional failure; aromatic carboxylic acids (such as phenylpyruvic acid): Although they can improve the rigidity of the coating, local overheating can easily cause molecular chain degradation, affecting the consistency of product performance. In addition, the traditional heavy-duty anti-corrosion coating formula design is single, lacking targeted functional components (such as anti-rust pigments and corrosion-resistant fillers), resulting in key indicators such as salt spray resistance and adhesion of the coating that are difficult to meet the requirements of harsh environments.

[0005] Therefore, developing a continuous process based on microfluidic field technology and compatible with multiple types of carboxylic acids to prepare bio-based polyols with high hydroxyl value, low viscosity and controllable structure, and further optimizing the coating formulation to improve the comprehensive anti-corrosion performance of the coating has become a technical problem that the industry urgently needs to break through. Summary of the invention

[0006] The technical problem to be solved by the present invention is that the traditional heavy-duty anti-corrosion coatings in the prior art rely on petroleum-based polyols, which lead to non-renewable resources, low synthesis efficiency, high product viscosity and single function. The present invention proposes a method for preparing bio-based polyols based on microfluidic field reaction technology. Through the synergistic effect of a specific carboxylic acid ring-opening reagent and a microchannel reactor, bio-based polyols with high hydroxyl value (≥170 mg KOH / g), low viscosity (≤800 mPa·s) and controllable molecular chain structure are prepared, and a heavy-duty anti-corrosion coating with high hardness, wear resistance and chemical corrosion resistance is further developed to break through the technical bottlenecks of traditional processes in environmental protection, performance and production efficiency.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0008] The invention discloses a method for preparing a bio-based polyol, comprising the steps of taking epoxidized vegetable oil as a first mixed liquid; mixing a carboxylic acid ring-opening reagent with a catalyst to obtain a second mixed liquid; pumping the first mixed liquid and the second mixed liquid into a microfluidic reactor of a microfluidic reactor device to perform a ring-opening reaction, and performing post-treatment after the reaction to obtain the bio-based polyol;

[0009] Wherein, the carboxylic acid ring-opening reagent is any one or a combination of 2-ethylhexanoic acid, 3,4-diethoxybenzoic acid, 3-indolecarboxylic acid, 2-cyclohexenecarboxylic acid, phenylpyruvic acid, levulinic acid, cyclohexanecarboxylic acid, 3-(3-ethylcyclopentyl)propionic acid, 3-ethoxypropionic acid, 2-hydroxybenzoic acid, 2-pyridinecarboxylic acid, indole-4-carboxylic acid and trimethylpyruvic acid.

[0010] In some embodiments, the epoxidized vegetable oil is any one or a combination of epoxidized soybean oil, epoxidized castor oil, epoxidized linseed oil, epoxidized rapeseed oil and epoxidized sunflower oil; and / or, the catalyst is any one or a combination of tetrafluoroboric acid, sulfuric acid, phosphoric acid, p-toluenesulfonic acid and methanesulfonic acid; and / or, when the carboxylic acid ring-opening reagent is a liquid, the carboxylic acid ring-opening reagent is mixed with the catalyst to obtain a second mixed liquid; and / or, when the carboxylic acid ring-opening reagent is a solid, the carboxylic acid ring-opening reagent is mixed with the catalyst and a solvent to obtain a second mixed liquid; and / or, the solvent is any one or a combination of dimethyl sulfoxide, N,N-dimethylformamide, tetrahydrofuran and acetonitrile.

[0011] Wherein, when the catalyst is tetrafluoroboric acid, it exists in the form of an aqueous solution.

[0012] In some embodiments, preferably, the epoxidized vegetable oil is epoxidized soybean oil; and / or, the catalyst is tetrafluoroboric acid; and / or, when the carboxylic acid ring-opening reagent is a liquid, the carboxylic acid ring-opening reagent is mixed with the catalyst to obtain a second mixed liquid; and / or, when the carboxylic acid ring-opening reagent is a solid, the carboxylic acid ring-opening reagent is mixed with the catalyst and a solvent to obtain a second mixed liquid; and / or, the solvent is dimethyl sulfoxide.

[0013] Among them, there is no special requirement for the amount of the solvent. The amount of the solvent and the flow rate of the second mixed liquid pumped into the microfluidic reactor of the microfluidic reactor reaction device are coordinated to control the molar ratio of the epoxy groups in the epoxidized vegetable oil to the carboxyl groups in the carboxylic acid ring-opening reagent, and the ratio of the catalyst to the total mass of the epoxidized vegetable oil and the carboxylic acid ring-opening reagent to be within the protection range.

[0014] In some embodiments, during the ring-opening reaction, the molar ratio of the epoxy group in the epoxidized vegetable oil to the carboxyl group in the carboxylic acid ring-opening reagent is 1:(1.3~1.6); and / or, during the ring-opening reaction, the catalyst accounts for 0.5%~3.0% of the total mass of the epoxidized vegetable oil and the carboxylic acid ring-opening reagent; and / or, the reaction temperature of the ring-opening reaction is 70℃~120℃; and / or, the reaction pressure of the ring-opening reaction is 0.2 MPa~0.6 MPa; and / or, the reaction residence time of the ring-opening reaction is 5 min~15 min; and / or, the microfluidic field reaction device includes a connecting pipe, a first feed pump, a second feed pump, a micromixer, a microfluidic field reactor and a receiver, wherein the first feed pump and the second feed pump are connected to the micromixer in parallel through a connecting pipe, and the micromixer, the microfluidic field reactor and the receiver are connected in series in sequence through a connecting pipe.

[0015] Among them, the reason for applying pressure in the ring-opening reaction is that, for example, when the catalyst is tetrafluoroboric acid, tetrafluoroboric acid exists in the form of an aqueous solution, and water will vaporize under normal pressure. Pressurization can increase the boiling point, and the diameter of the microchannel is only about 0.5 mm to 2.0 mm. If water vaporization produces bubbles, the laminar flow state will be destroyed, resulting in unstable flow. Pressurization can ensure the stability of continuous flow.

[0016] In some embodiments, preferably, during the ring-opening reaction, the molar ratio of the epoxy group in the epoxidized vegetable oil to the carboxyl group in the carboxylic acid ring-opening reagent is 1:(1.3~1.6); and / or, during the ring-opening reaction, the catalyst accounts for 1.0%~3.0% of the total mass of the epoxidized vegetable oil and the carboxylic acid ring-opening reagent; and / or, the reaction temperature of the ring-opening reaction is 75°C~110°C; and / or, the reaction pressure of the ring-opening reaction is 0.3 MPa~0.6 MPa; and / or, the reaction residence time of the ring-opening reaction is 8 min~15 min; and / or, the microfluidic field reaction device includes a connecting pipe, a first feed pump, a second feed pump, a micromixer, a microfluidic field reactor and a receiver, wherein the first feed pump and the second feed pump are connected to the micromixer in parallel through a connecting pipe, and the micromixer, the microfluidic field reactor and the receiver are connected in series in sequence through a connecting pipe.

[0017] Wherein, the micro mixer is a Y-type micro mixer or a T-type micro mixer, preferably a Y-type micro mixer.

[0018] Wherein, the microfluidic field reactor is a tubular reactor, and the inner diameter of the tube is 0.5 mm~2.0 mm, preferably 0.8 mm~2.0 mm.

[0019] Wherein, the inner wall of the channel of the microfluidic field reactor is treated with a hydrophobic coating, and the pressure fluctuation is ≤±0.05 MPa.

[0020] Wherein, the reaction temperature in the microfluidic field reactor is controlled by heating with an oil bath.

[0021] After the ring-opening reaction is completed, the reaction solution is extracted with a saturated sodium carbonate aqueous solution, washed with distilled water until neutral, then dried over anhydrous sodium sulfate to remove water, and then unreacted carboxylic acid is removed by reduced pressure distillation, and then purified by activated carbon adsorption to obtain bio-based polyols.

[0022] The bio-based polyols prepared by the above-mentioned preparation method are also within the protection scope of the present invention.

[0023] In some embodiments, the hydroxyl value of the bio-based polyol is 170-210 mg KOH / g; and / or the viscosity of the bio-based polyol is less than or equal to 800 mPa·s (25° C.).

[0024] The use of the above-mentioned bio-based polyols in the preparation of heavy-duty anti-corrosion coatings is also within the protection scope of the present invention.

[0025] Furthermore, the present invention discloses a heavy-duty anticorrosive coating, comprising the following components in parts by weight:

[0026] 50-60 parts of the above-mentioned bio-based polyol;

[0027] Isocyanate, 25-35 parts;

[0028] Chain extender, 6-10 parts;

[0029] Anti-rust pigment, 8-12 parts;

[0030] Corrosion-resistant filler, 4 to 8 parts;

[0031] Hydrophilic chain extender, 2~6 parts.

[0032] In some embodiments, the isocyanate is hexamethylene diisocyanate or isophorone diisocyanate; and / or the chain extender is any one or a combination of ethylenediamine, diethylenetriamine and isophoronediamine; and / or the rust-proof pigment is any one or a combination of red iron oxide, mica iron oxide, iron tannate and aluminum tripolyphosphate; and / or the corrosion-resistant filler is any one or a combination of wet-process sericite, titanium dioxide and barite powder; and / or the hydrophilic chain extender is any one or a combination of dihydroxymethylpropionic acid, dihydroxymethylbutyric acid and sodium ethylenediamine sulfonate.

[0033] In some embodiments, preferably, the isocyanate is hexamethylene diisocyanate; and / or, the chain extender is ethylenediamine; and / or, the anti-rust pigment is red iron oxide; and / or, the corrosion-resistant filler is wet-process sericite; and / or, the hydrophilic chain extender is dihydroxymethyl propionic acid.

[0034] Furthermore, the present invention discloses a method for preparing the above-mentioned heavy-duty anti-corrosion coating, which comprises mixing the above-mentioned bio-based polyol with isocyanate in parts by weight to carry out a prepolymerization reaction; subsequently, adding a chain extender, an anti-rust pigment, a corrosion-resistant filler, and a hydrophilic chain extender to carry out a chain extension reaction; finally, adding an alkali to adjust the pH to neutral, emulsifying, and adding deionized water to adjust the solid content to obtain the heavy-duty anti-corrosion coating.

[0035] In some embodiments, the isocyanate is hexamethylene diisocyanate or isophorone diisocyanate; and / or, the chain extender is any one or a combination of ethylenediamine, diethylenetriamine and isophoronediamine; and / or, the anti-rust pigment is any one or a combination of red iron oxide, mica iron oxide, iron tannate and aluminum tripolyphosphate; and / or, the corrosion-resistant filler is any one or a combination of wet-process sericite, titanium dioxide and barite powder; and / or, the hydrophilic chain extender is any one of dihydroxymethylpropionic acid, dihydroxymethylbutyric acid and sodium ethylenediamine ethanesulfonate. or a combination of any one or more thereof; and / or, the base is any one or a combination of triethylamine, dimethylethanolamine and triethanolamine; and / or, the reaction temperature of the prepolymerization reaction is 75-80° C.; and / or, the reaction time of the prepolymerization reaction is 2-3 hours; and / or, the reaction temperature of the chain extension reaction is 75-85° C.; and / or, the reaction time of the chain extension reaction is 1-2 hours; and / or, the emulsification is carried out at room temperature; and / or, the emulsification time is 20-40 minutes; and / or, the emulsification is carried out under centrifugation at a centrifugal speed of 6000-8000 rpm; and / or, deionized water is added to adjust the solid content to 40%-45%.

[0036] In some embodiments, preferably, the isocyanate is hexamethylene diisocyanate; and / or, the chain extender is ethylenediamine; and / or, the rust-proof pigment is red iron oxide; and / or, the corrosion-resistant filler is wet-process sericite; and / or, the hydrophilic chain extender is dihydroxymethylpropionic acid; and / or, the base is triethylamine; and / or, the prepolymerization reaction has a reaction temperature of 75°C; and / or, the prepolymerization reaction has a reaction time of 2 to 3 hours; and / or, the chain extension reaction has a reaction temperature of 80°C; and / or, the chain extension reaction has a reaction time of 1 to 2 hours; and / or, the emulsification is carried out at room temperature; and / or, the emulsification time is 30 minutes; and / or, the emulsification is carried out under centrifugation at a centrifugal speed of 8000 rpm; and / or, deionized water is added to adjust the solid content to 40%.

[0037] The use of the above-mentioned heavy-duty anti-corrosion coating in the preparation of anti-corrosion coatings and / or in the preparation of anti-corrosion materials is also within the protection scope of the present invention.

[0038] The use of the heavy-duty anti-corrosion coating prepared by the above-mentioned preparation method in the preparation of anti-corrosion coatings and / or in the preparation of anti-corrosion materials is also within the protection scope of the present invention.

[0039] Beneficial effects:

[0040] (1) The present invention can achieve efficient mass and heat transfer through microfluidic field technology, avoid side reactions and significantly shorten the reaction time, greatly reduce energy consumption, and at the same time improve the stability of the product hydroxyl value.

[0041] (2) The present invention uses a carboxylic acid ring-opening reagent to open the epoxy vegetable oil and introduce ester bonds, heterocycles and double bonds in a targeted manner. The viscosity of the obtained bio-based polyol is significantly reduced, the flexibility of the molecular chain and the cross-linking density are synergistically optimized, and the hardness of the coating is significantly improved.

[0042] (3) The heavy-duty anti-corrosion coating prepared by the present invention has significantly enhanced salt spray resistance and adhesion, and is suitable for harsh environments. Its wear resistance and chemical corrosion resistance are better than those of traditional products.

[0043] (4) The present invention replaces petroleum-based resources with bio-based raw materials, effectively reducing VOC emissions and meeting the needs of sustainable development.

[0044] (5) The microfluidic field technology used in the present invention is suitable for carboxylic acid systems containing complex functional groups, breaking through the limitations of traditional processes on reaction reagents and broadening the range of raw material selection.

[0045] (6) The present invention combines microfluidics with specific carboxylic acid ring-opening reagents (such as those containing ester bonds, heterocyclic structures, etc.). The microfluidics significantly shortens the reaction time to 8-15 minutes, and the bio-based polyols obtained have a hydroxyl value of 185-210 mg KOH / g and a viscosity of ≤760 mPa·s, and give the coating a high crosslinking density (7.0×10⁻ 4 mol / cm³~10.1×10⁻ 4 mol / cm³), excellent salt spray resistance (≥800 h), pencil hardness (2H~4H) and chemical corrosion resistance (alkali / acid / oil resistance, etc.), surpassing the effect of traditional alcohols or ordinary structure carboxylic acids as ring-opening reagents, and realizing efficient, environmentally friendly and high-performance heavy-duty anti-corrosion coating preparation.

[0046] (7) In order to solve the problems of low reaction efficiency, high product viscosity and single function caused by alcohol ring-opening reagents in traditional processes, the present invention uses microfluidic field technology to carry out ring-opening reaction of epoxy vegetable oil with specific carboxylic acid ring-opening reagents to prepare low-viscosity, high-hydroxyl value bio-based polyols containing ester bonds / heterocyclic structures. The bio-based polyols are further copolymerized with isocyanates, chain extenders and functional fillers to obtain heavy-duty anti-corrosion coatings with high hardness, wear resistance and chemical corrosion resistance, which are suitable for metal corrosion protection in harsh environments. The present invention realizes efficient and continuous production through microfluidic field technology, breaks through the limitations of traditional processes on complex carboxylic acid systems, and significantly improves coating performance and environmental friendliness. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments, and the above and / or other advantages of the present invention will become more clear.

[0048] Figure 1 Schematic diagram of the microfluidic field reaction device used in an embodiment of the present invention.

[0049] Figure 2 The effect of catalyst dosage on the epoxy value of bio-based polyols. DETAILED DESCRIPTION

[0050] The present invention can be better understood according to the following examples. However, it is easy for those skilled in the art to understand that the contents described in the examples are only used to illustrate the present invention, and should not and will not limit the present invention described in detail in the claims.

[0051] The experimental methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials described are commercially available unless otherwise specified.

[0052] The microfluidic reaction device used in the embodiment of the present invention is shown in FIG. Figure 1 The microfluidic reaction device includes a connecting pipe, a first feed pump, a second feed pump, a micromixer, a microfluidic reactor and a receiver; wherein the first feed pump and the second feed pump are connected to the micromixer in parallel through a connecting pipe; the micromixer, the microfluidic reactor and the receiver are connected in series in sequence through a connecting pipe.

[0053] Among them, the microfluidic field reactor adopts a pore structure design.

[0054] Wherein, the reaction temperature of the microfluidic field reactor is controlled by heating in an oil bath.

[0055] Example 1

[0056] (1) Preparation of bio-based polyols

[0057] Epoxidized soybean oil (epoxy value 6.5%) is recorded as the first mixed liquid; 2-ethylhexanoic acid (liquid) and 48 wt%~50wt% tetrafluoroboric acid aqueous solution are mixed to obtain a second mixed liquid.

[0058] The first mixed liquid and the second mixed liquid were pumped into the microfluidic reactor (channel diameter 1.0 mm, inner wall treated with perfluoroalkylsilane hydrophobic coating, volume 80 mL) of the microfluidic reactor device for ring-opening reaction, the reaction temperature was controlled to 85℃, the reaction pressure was controlled to 0.4 MPa, and the reaction residence time of the ring-opening reaction in the microfluidic reactor was 10min. In the process of the reaction, the flow rate of the first mixed liquid and the second mixed liquid was adjusted to control the molar ratio of the epoxy group in the epoxidized soybean oil to the carboxylic acid group in the 2-ethylhexanoic acid to be 1:1.3, and the mass of tetrafluoroboric acid accounted for 1.0% of the total mass of the epoxidized soybean oil and 2-ethylhexanoic acid. After the reaction, the reaction liquid was extracted with a saturated sodium carbonate aqueous solution, washed with distilled water to neutrality, then dried with anhydrous sodium sulfate to remove water, and then removed the unreacted carboxylic acid by reduced pressure distillation (80℃, -0.09 MPa), and then purified by activated carbon adsorption (the amount of activated carbon was 5% of the product mass) to obtain a light yellow transparent liquid, that is, bio-based polyol.

[0059] The bio-based polyol prepared in this example has a hydroxyl value of 195 mg KOH / g (titration method GB / T 12008.3-2009) and a viscosity of 750 mPa·s (25° C., measured by a rotational viscometer).

[0060] (2) Preparation of heavy-duty anti-corrosion coatings

[0061] Bio-based polyol (55 parts by mass, prepared in step (1) of this embodiment) and hexamethylene diisocyanate (HDI, 30 parts by mass) were added to a reactor and prepolymerized at 75°C for 2.5 hours under nitrogen protection; then ethylenediamine (8 parts by mass), red iron oxide (10 parts by mass), wet-process sericite (6 parts by mass) and dimethylolpropionic acid (4 parts by mass) were added, and the temperature was raised to 80°C for chain extension reaction for 1.5 hours; triethylamine was added to neutralize to pH = 7, and high-speed emulsification was performed at 8000 rpm at room temperature for 30 minutes, and deionized water was added to adjust the solid content to 40%, thereby preparing a heavy-duty anti-corrosion coating.

[0062] Example 2

[0063] (1) Preparation of bio-based polyols

[0064] Epoxidized soybean oil (epoxy value 6.5%) is recorded as the first mixed liquid; 3,4-diethoxybenzoic acid, 48 wt%~50 wt% tetrafluoroboric acid aqueous solution and DMSO are mixed to obtain a second mixed liquid.

[0065] The first mixed liquid and the second mixed liquid were pumped into the microfluidic reactor (channel diameter 0.8 mm, inner wall treated with perfluoroalkylsilane hydrophobic coating, volume 120 mL) of the microfluidic reactor device for ring-opening reaction, the reaction temperature was controlled to 95°C, the reaction pressure was controlled to 0.5 MPa, and the reaction residence time of the ring-opening reaction in the microfluidic reactor was 12 min. During the reaction, the flow rate of the first mixed liquid and the second mixed liquid was adjusted, and the molar ratio of the epoxy group in the epoxidized soybean oil to the carboxyl group in the 3,4-diethoxybenzoic acid was controlled to be 1:1.5 during the reaction, and the mass of tetrafluoroboric acid accounted for 1.0% of the total mass of the epoxidized soybean oil and 3,4-diethoxybenzoic acid. After the reaction, the reaction solution was extracted with a saturated sodium carbonate aqueous solution, washed with distilled water until neutral, then dried over anhydrous sodium sulfate to remove water, and then distilled under reduced pressure (80°C, -0.09 MPa) to remove unreacted carboxylic acid. The product was then purified by activated carbon adsorption (the amount of activated carbon was 5% of the product mass) to obtain a light yellow transparent liquid, namely, bio-based polyol.

[0066] The bio-based polyol prepared in this example has a hydroxyl value of 205 mg KOH / g (titration method GB / T 12008.3-2009) and a viscosity of 680 mPa·s (25° C., measured by a rotational viscometer).

[0067] (2) Preparation of heavy-duty anti-corrosion coatings

[0068] Bio-based polyol (60 parts by mass, prepared in step (1) of this embodiment) and hexamethylene diisocyanate (HDI, 35 parts by mass) were added to a reactor and prepolymerized at 75°C for 2.5 hours under nitrogen protection; then ethylenediamine (10 parts by mass), red iron oxide (12 parts by mass), wet-process sericite (8 parts by mass) and dimethylolpropionic acid (6 parts by mass) were added, and the temperature was raised to 80°C for chain extension reaction for 1.5 hours; triethylamine was added to neutralize to pH = 7, and high-speed emulsification was performed at 8000 rpm at room temperature for 30 minutes, and deionized water was added to adjust the solid content to 40%, thereby preparing a heavy-duty anti-corrosion coating.

[0069] Example 3

[0070] (1) Preparation of bio-based polyols

[0071] Epoxidized soybean oil (epoxy value 6.5%) is recorded as the first mixed solution; 3-indolecarboxylic acid, 48 wt%~50 wt% tetrafluoroboric acid aqueous solution and DMSO are mixed to obtain a second mixed solution.

[0072] The first mixed liquid and the second mixed liquid were pumped into the microfluidic reactor (channel diameter 1.2 mm, inner wall treated with perfluoroalkylsilane hydrophobic coating, volume 56 mL) of the microfluidic reactor device for ring-opening reaction, the reaction temperature was controlled to 75℃, the reaction pressure was controlled to 0.3 MPa, and the reaction residence time of the ring-opening reaction in the microfluidic reactor was 8 min. During the reaction, the flow rate of the first mixed liquid and the second mixed liquid was adjusted to control the molar ratio of the epoxy group in the epoxidized soybean oil to the carboxylic acid group in the 3-indolecarboxylic acid to be 1:1.5, and the mass of tetrafluoroboric acid accounted for 1.0% of the total mass of the epoxidized soybean oil and 3-indolecarboxylic acid. After the reaction, the reaction liquid was extracted with a saturated sodium carbonate aqueous solution, washed with distilled water to neutrality, then dried with anhydrous sodium sulfate to remove water, and then removed the unreacted carboxylic acid by reduced pressure distillation (80℃, -0.09 MPa), and then purified by activated carbon adsorption (the amount of activated carbon was 5% of the product mass) to obtain a light brown liquid, that is, bio-based polyol.

[0073] The bio-based polyol prepared in this example has a hydroxyl value of 185 mg KOH / g (titration method GB / T12008.3-2009) and a viscosity of 720 mPa·s (25° C., measured by a rotational viscometer).

[0074] (2) Preparation of heavy-duty anti-corrosion coatings

[0075] Bio-based polyol (55 parts by mass, prepared in step (1) of this embodiment) and hexamethylene diisocyanate (HDI, 30 parts by mass) were added to a reactor and prepolymerized at 75°C for 2.5 hours under nitrogen protection; then ethylenediamine (8 parts by mass), red iron oxide (10 parts by mass), wet-process sericite (6 parts by mass) and dimethylolpropionic acid (4 parts by mass) were added, and the temperature was raised to 80°C for chain extension reaction for 1.5 hours; triethylamine was added to neutralize to pH = 7, and high-speed emulsification was performed at 8000 rpm at room temperature for 30 minutes, and deionized water was added to adjust the solid content to 40%, thereby preparing a heavy-duty anti-corrosion coating.

[0076] Example 4

[0077] (1) Preparation of bio-based polyols

[0078] Epoxidized soybean oil (epoxy value 6.5%) is recorded as the first mixed liquid; 2-cyclohexenecarboxylic acid, 48 wt%~50 wt% tetrafluoroboric acid aqueous solution and DMSO are mixed to obtain a second mixed liquid.

[0079] The first mixed liquid and the second mixed liquid were pumped into the microfluidic reactor (channel diameter 2.0 mm, inner wall treated with perfluoroalkylsilane hydrophobic coating, volume 180 mL) of the microfluidic reactor device for ring-opening reaction, the reaction temperature was controlled to be 110℃, the reaction pressure was controlled to be 0.6 MPa, and the reaction residence time of the ring-opening reaction in the microfluidic reactor was 15min. During the reaction, the flow rate of the first mixed liquid and the second mixed liquid was adjusted, and the molar ratio of the epoxy group in the epoxidized soybean oil to the carboxylic acid group in the 2-cyclohexenecarboxylic acid was controlled to be 1:1.6 during the reaction, and the mass of tetrafluoroboric acid accounted for 1.0% of the total mass of the epoxidized soybean oil and the 2-cyclohexenecarboxylic acid. After the reaction, the reaction solution was extracted with a saturated sodium carbonate aqueous solution, washed with distilled water until neutral, then dried over anhydrous sodium sulfate to remove water, and then distilled under reduced pressure (80°C, -0.09 MPa) to remove unreacted carboxylic acid. The product was then purified by activated carbon adsorption (the amount of activated carbon was 5% of the product mass) to obtain a light yellow transparent liquid, namely, bio-based polyol.

[0080] The bio-based polyol prepared in this example had a hydroxyl value of 210 mg KOH / g (titration method GB / T12008.3-2009) and a viscosity of 650 mPa·s (25° C., measured by a rotational viscometer).

[0081] (2) Preparation of heavy-duty anti-corrosion coatings

[0082] Bio-based polyol (55 parts by mass, prepared in step (1) of this embodiment) and hexamethylene diisocyanate (HDI, 30 parts by mass) were added to a reactor and prepolymerized at 75°C for 2.5 hours under nitrogen protection; then ethylenediamine (8 parts by mass), red iron oxide (10 parts by mass), wet-process sericite (6 parts by mass) and dimethylolpropionic acid (4 parts by mass) were added, and the temperature was raised to 80°C for chain extension reaction for 1.5 hours; triethylamine was added to neutralize to pH = 7, and high-speed emulsification was performed at 8000 rpm at room temperature for 30 minutes, and deionized water was added to adjust the solid content to 40%, thereby preparing a heavy-duty anti-corrosion coating.

[0083] Example 5

[0084] (1) Preparation of bio-based polyols

[0085] Epoxidized soybean oil (epoxy value 6.5%) is recorded as the first mixed liquid; phenylpyruvic acid and 48 wt%~50 wt% tetrafluoroboric acid aqueous solution are mixed to obtain a second mixed liquid.

[0086] The first mixed liquid and the second mixed liquid were pumped into the microfluidic reactor (channel diameter 1.0 mm, inner wall treated with perfluoroalkylsilane hydrophobic coating, volume 96 mL) of the microfluidic reactor device for ring-opening reaction, the reaction temperature was controlled to be 95℃, the reaction pressure was controlled to be 0.5 MPa, and the reaction residence time of the ring-opening reaction in the microfluidic reactor was 12min. In the process of the reaction, the flow rate of the first mixed liquid and the second mixed liquid was adjusted to control the molar ratio of the epoxy group in the epoxidized soybean oil to the carboxylic acid group in the phenylpyruvic acid to be 1:1.6, and the mass of tetrafluoroboric acid accounted for 1.0% of the total mass of the epoxidized soybean oil and phenylpyruvic acid. After the reaction, the reaction liquid was extracted with a saturated sodium carbonate aqueous solution, washed with distilled water to neutrality, then dried with anhydrous sodium sulfate to remove water, and then removed the unreacted carboxylic acid by reduced pressure distillation (80℃, -0.09 MPa), and then purified by activated carbon adsorption (the amount of activated carbon was 5% of the product mass) to obtain a light yellow transparent liquid, that is, bio-based polyol.

[0087] The bio-based polyol prepared in this example has a hydroxyl value of 200 mg KOH / g (titration method GB / T12008.3-2009) and a viscosity of 720 mPa·s (25° C., measured by a rotational viscometer).

[0088] (2) Preparation of heavy-duty anti-corrosion coatings

[0089] Bio-based polyol (55 parts by mass, prepared in step (1) of this embodiment) and hexamethylene diisocyanate (HDI, 30 parts by mass) were added to a reactor and prepolymerized at 75°C for 2.5 hours under nitrogen protection; then ethylenediamine (8 parts by mass), red iron oxide (10 parts by mass), wet-process sericite (6 parts by mass) and dimethylolpropionic acid (4 parts by mass) were added, and the temperature was raised to 80°C for chain extension reaction for 1.5 hours; triethylamine was added to neutralize to pH = 7, and high-speed emulsification was performed at 8000 rpm at room temperature for 30 minutes, and deionized water was added to adjust the solid content to 40%, thereby preparing a heavy-duty anti-corrosion coating.

[0090] Example 6

[0091] (1) Preparation of bio-based polyols

[0092] Epoxidized soybean oil (epoxy value 6.5%) is recorded as the first mixed liquid; levulinic acid, 48 wt%~50 wt% tetrafluoroboric acid aqueous solution and DMSO are mixed to obtain a second mixed liquid.

[0093] The first mixed liquid and the second mixed liquid were pumped into the microfluidic reactor (channel diameter 1.0 mm, inner wall treated with perfluoroalkylsilane hydrophobic coating, volume 84 mL) of the microfluidic reactor device for ring-opening reaction, the reaction temperature was controlled at 90℃, the reaction pressure was controlled at 0.4 MPa, and the reaction residence time of the ring-opening reaction in the microfluidic reactor was 10min. In the process of the reaction, the flow rate of the first mixed liquid and the second mixed liquid was adjusted to control the molar ratio of the epoxy group in the epoxidized soybean oil to the carboxylic acid group in the levulinic acid to be 1:1.4, and the mass of tetrafluoroboric acid accounted for 1.0% of the total mass of the epoxidized soybean oil and levulinic acid. After the reaction, the reaction liquid was extracted with a saturated sodium carbonate aqueous solution, washed with distilled water to neutrality, then dried with anhydrous sodium sulfate to remove water, and then removed the unreacted carboxylic acid by reduced pressure distillation (80℃, -0.09 MPa), and then purified by activated carbon adsorption (the amount of activated carbon was 5% of the product mass) to obtain a light yellow transparent liquid, that is, bio-based polyol.

[0094] The bio-based polyol prepared in this example has a hydroxyl value of 190 mg KOH / g (titration method GB / T12008.3-2009) and a viscosity of 700 mPa·s (25° C., measured by a rotational viscometer).

[0095] (2) Preparation of heavy-duty anti-corrosion coatings

[0096] Bio-based polyol (50 parts by mass, prepared in step (1) of this embodiment) and hexamethylene diisocyanate (HDI, 25 parts by mass) were added to a reactor and prepolymerized at 75°C for 2.5 hours under nitrogen protection; then ethylenediamine (6 parts by mass), red iron oxide (8 parts by mass), wet-process sericite (4 parts by mass) and dimethylolpropionic acid (2 parts by mass) were added, and the temperature was raised to 80°C for chain extension reaction for 1.5 hours; triethylamine was added to neutralize to pH = 7, and high-speed emulsification was performed at 8000 rpm at room temperature for 30 minutes, and deionized water was added to adjust the solid content to 40%, thereby preparing a heavy-duty anti-corrosion coating.

[0097] Example 7

[0098] (1) Preparation of bio-based polyols

[0099] Epoxidized soybean oil (epoxy value 6.5%) is recorded as the first mixed liquid; cyclohexanecarboxylic acid, 48 wt%~50 wt% tetrafluoroboric acid aqueous solution and DMSO are mixed to obtain a second mixed liquid.

[0100] The first mixed liquid and the second mixed liquid were pumped into the microfluidic reactor (channel diameter 1.0 mm, inner wall treated with perfluoroalkylsilane hydrophobic coating, volume 108 mL) of the microfluidic reactor device for ring-opening reaction, the reaction temperature was controlled to be 100℃, the reaction pressure was controlled to be 0.5 MPa, and the reaction residence time of the ring-opening reaction in the microfluidic reactor was 12min. In the process of the reaction, the flow rate of the first mixed liquid and the second mixed liquid was adjusted, the molar ratio of the epoxy group in the epoxidized soybean oil to the carboxylic acid group in the cyclohexanecarboxylic acid was controlled to be 1:1.5, and the mass of tetrafluoroboric acid accounted for 1.0% of the total mass of the epoxidized soybean oil and cyclohexanecarboxylic acid. After the reaction, the reaction liquid was extracted with a saturated sodium carbonate aqueous solution, washed with distilled water to neutrality, then dried with anhydrous sodium sulfate to remove water, and then removed the unreacted carboxylic acid by reduced pressure distillation (80℃, -0.09 MPa), and then purified by activated carbon adsorption (the amount of activated carbon was 5% of the product mass) to obtain a light yellow transparent liquid, that is, bio-based polyol.

[0101] The bio-based polyol prepared in this example has a hydroxyl value of 200 mg KOH / g (titration method GB / T12008.3-2009) and a viscosity of 720 mPa·s (25° C., measured by a rotational viscometer).

[0102] (2) Preparation of heavy-duty anti-corrosion coatings

[0103] Bio-based polyol (58 parts by mass, prepared in step (1) of this embodiment) and hexamethylene diisocyanate (HDI, 32 parts by mass) were added to a reactor and prepolymerized at 75°C for 2.5 hours under nitrogen protection; then ethylenediamine (9 parts by mass), red iron oxide (11 parts by mass), wet-process sericite (7 parts by mass) and dimethylolpropionic acid (5 parts by mass) were added, and the temperature was raised to 80°C for chain extension reaction for 1.5 hours; triethylamine was added to neutralize to pH = 7, and high-speed emulsification was performed at 8000 rpm at room temperature for 30 minutes, and deionized water was added to adjust the solid content to 40%, thereby preparing a heavy-duty anti-corrosion coating.

[0104] Example 8

[0105] (1) Preparation of bio-based polyols

[0106] Epoxidized soybean oil (epoxy value 6.5%) is recorded as the first mixed liquid; 3-(3-ethylcyclopentyl) propionic acid, 48 wt%~50 wt% tetrafluoroboric acid aqueous solution and DMSO are mixed to obtain a second mixed liquid.

[0107] The first mixed liquid and the second mixed liquid were pumped into the microfluidic reactor (channel diameter 1.0 mm, inner wall treated with perfluoroalkylsilane hydrophobic coating, volume 84 mL) of the microfluidic reactor device for ring-opening reaction, the reaction temperature was controlled to 95℃, the reaction pressure was controlled to 0.4 MPa, and the reaction residence time of the ring-opening reaction in the microfluidic reactor was 10min. During the reaction, the flow rate of the first mixed liquid and the second mixed liquid was adjusted, and the molar ratio of the epoxy group in the epoxidized soybean oil to the carboxylic acid group in the 3-(3-ethylcyclopentyl) propionic acid was controlled to be 1:1.4 during the reaction, and the mass of tetrafluoroboric acid accounted for 1.0% of the total mass of the epoxidized soybean oil and 3-(3-ethylcyclopentyl) propionic acid. After the reaction, the reaction solution was extracted with a saturated sodium carbonate aqueous solution, washed with distilled water until neutral, then dried over anhydrous sodium sulfate to remove water, and then distilled under reduced pressure (80°C, -0.09 MPa) to remove unreacted carboxylic acid. The product was then purified by activated carbon adsorption (the amount of activated carbon was 5% of the product mass) to obtain a light yellow transparent liquid, namely, bio-based polyol.

[0108] The bio-based polyol prepared in this example has a hydroxyl value of 198 mg KOH / g (titration method GB / T12008.3-2009) and a viscosity of 710 mPa·s (25° C., measured by a rotational viscometer).

[0109] (2) Preparation of heavy-duty anti-corrosion coatings

[0110] Bio-based polyol (52 parts by mass, prepared in step (1) of this embodiment) and hexamethylene diisocyanate (HDI, 28 parts by mass) were added to a reactor and prepolymerized at 75°C for 2.5 hours under nitrogen protection; then ethylenediamine (7 parts by mass), red iron oxide (9 parts by mass), wet-process sericite (5 parts by mass) and dimethylolpropionic acid (3 parts by mass) were added, and the temperature was raised to 80°C for chain extension reaction for 1.5 hours; triethylamine was added to neutralize to pH = 7, and high-speed emulsification was performed at 8000 rpm at room temperature for 30 minutes, and deionized water was added to adjust the solid content to 40%, thereby preparing a heavy-duty anti-corrosion coating.

[0111] Example 9

[0112] (1) Preparation of bio-based polyols

[0113] Epoxidized soybean oil (epoxy value 6.5%) is recorded as the first mixed liquid; 3-ethoxypropionic acid and 48 wt%~50 wt% tetrafluoroboric acid aqueous solution are mixed to obtain a second mixed liquid.

[0114] The first mixed liquid and the second mixed liquid were pumped into the microfluidic reactor (channel diameter 1.0 mm, inner wall treated with perfluoroalkylsilane hydrophobic coating, volume 90 mL) of the microfluidic reactor device for ring-opening reaction, the reaction temperature was controlled to be 90℃, the reaction pressure was controlled to be 0.4 MPa, and the reaction residence time of the ring-opening reaction in the microfluidic reactor was 10min. In the process of the reaction, the flow rate of the first mixed liquid and the second mixed liquid was adjusted to control the molar ratio of the epoxy group in the epoxidized soybean oil to the carboxylic acid group in the 3-ethoxypropionic acid to be 1:1.5, and the mass of tetrafluoroboric acid accounted for 1.0% of the total mass of the epoxidized soybean oil and 3-ethoxypropionic acid. After the reaction, the reaction liquid was extracted with a saturated sodium carbonate aqueous solution, washed with distilled water to neutrality, then dried with anhydrous sodium sulfate to remove water, and then removed the unreacted carboxylic acid by reduced pressure distillation (80℃, -0.09 MPa), and then purified by activated carbon adsorption (the amount of activated carbon was 5% of the product mass) to obtain a light yellow transparent liquid, that is, bio-based polyol.

[0115] The bio-based polyol prepared in this example has a hydroxyl value of 185 mg KOH / g (titration method GB / T12008.3-2009) and a viscosity of 690 mPa·s (25° C., measured by a rotational viscometer).

[0116] (2) Preparation of heavy-duty anti-corrosion coatings

[0117] Bio-based polyol (54 parts by mass, prepared in step (1) of this embodiment) and hexamethylene diisocyanate (HDI, 30 parts by mass) were added to a reactor and prepolymerized at 75°C for 2.5 hours under nitrogen protection; then ethylenediamine (8 parts by mass), red iron oxide (12 parts by mass), wet-process sericite (6 parts by mass) and dimethylolpropionic acid (4 parts by mass) were added, and the temperature was raised to 80°C for chain extension reaction for 1.5 hours; triethylamine was added to neutralize to pH = 7, and high-speed emulsification was performed at 8000 rpm at room temperature for 30 minutes, and deionized water was added to adjust the solid content to 40%, thereby preparing a heavy-duty anti-corrosion coating.

[0118] Example 10

[0119] (1) Preparation of bio-based polyols

[0120] Epoxidized soybean oil (epoxy value 6.5%) is recorded as the first mixed liquid; 2-hydroxybenzoic acid, 48 wt%~50 wt% tetrafluoroboric acid aqueous solution and DMSO are mixed to obtain a second mixed liquid.

[0121] The first mixed liquid and the second mixed liquid were pumped into the microfluidic reactor (channel diameter 1.0 mm, inner wall treated with perfluoroalkylsilane hydrophobic coating, volume 101 mL) of the microfluidic reactor device for ring-opening reaction, the reaction temperature was controlled to be 90℃, the reaction pressure was controlled to be 0.4 MPa, and the reaction residence time of the ring-opening reaction in the microfluidic reactor was 12min. During the reaction, the flow rate of the first mixed liquid and the second mixed liquid was adjusted to control the molar ratio of the epoxy group in the epoxidized soybean oil to the carboxylic acid group in the 2-hydroxybenzoic acid to be 1:1.5, and the mass of tetrafluoroboric acid accounted for 1.0% of the total mass of the epoxidized soybean oil and 2-hydroxybenzoic acid. After the reaction, the reaction liquid was extracted with a saturated sodium carbonate aqueous solution, washed with distilled water to neutrality, then dried with anhydrous sodium sulfate to remove water, and then removed the unreacted carboxylic acid by reduced pressure distillation (80℃, -0.09 MPa), and then purified by activated carbon adsorption (the amount of activated carbon was 5% of the product mass) to obtain a light yellow transparent liquid, that is, bio-based polyol.

[0122] The bio-based polyol prepared in this example has a hydroxyl value of 190 mg KOH / g (titration method GB / T12008.3-2009) and a viscosity of 710 mPa·s (25° C., measured by a rotational viscometer).

[0123] (2) Preparation of heavy-duty anti-corrosion coatings

[0124] Bio-based polyol (55 parts by mass, prepared in step (1) of this embodiment) and hexamethylene diisocyanate (HDI, 30 parts by mass) were added to a reactor and prepolymerized at 75°C for 2.5 hours under nitrogen protection; then ethylenediamine (8 parts by mass), red iron oxide (10 parts by mass), wet-process sericite (6 parts by mass) and dimethylolpropionic acid (4 parts by mass) were added, and the temperature was raised to 80°C for chain extension reaction for 1.5 hours; triethylamine was added to neutralize to pH = 7, and high-speed emulsification was performed at 8000 rpm at room temperature for 30 minutes, and deionized water was added to adjust the solid content to 40%, thereby preparing a heavy-duty anti-corrosion coating.

[0125] Embodiment 11

[0126] (1) Preparation of bio-based polyols

[0127] Epoxidized soybean oil (epoxy value 6.5%) is recorded as the first mixed solution; 2-picolinic acid, 48 wt%~50 wt% tetrafluoroboric acid aqueous solution and DMSO are mixed to obtain a second mixed solution.

[0128] The first mixed liquid and the second mixed liquid were pumped into the microfluidic reactor (channel diameter 1.0 mm, inner wall treated with perfluoroalkylsilane hydrophobic coating, volume 84 mL) of the microfluidic reactor device for ring-opening reaction, the reaction temperature was controlled to be 95℃, the reaction pressure was controlled to be 0.4 MPa, and the reaction residence time of the ring-opening reaction in the microfluidic reactor was 10min. In the process of the reaction, the flow rate of the first mixed liquid and the second mixed liquid was adjusted to control the molar ratio of the epoxy group in the epoxidized soybean oil to the carboxylic acid group in the 2-pyridine carboxylic acid to be 1:1.5, and the mass of tetrafluoroboric acid accounted for 1.0% of the total mass of the epoxidized soybean oil and 2-pyridine carboxylic acid. After the reaction, the reaction liquid was extracted with a saturated sodium carbonate aqueous solution, washed with distilled water to neutrality, then dried with anhydrous sodium sulfate to remove water, and then removed the unreacted carboxylic acid by reduced pressure distillation (80℃, -0.09 MPa), and then purified by activated carbon adsorption (the amount of activated carbon was 5% of the product mass) to obtain a light yellow transparent liquid, that is, bio-based polyol.

[0129] The bio-based polyol prepared in this example has a hydroxyl value of 195 mg KOH / g (titration method GB / T12008.3-2009) and a viscosity of 700 mPa·s (25° C., measured by a rotational viscometer).

[0130] (2) Preparation of heavy-duty anti-corrosion coatings

[0131] Bio-based polyol (56 parts by mass, prepared in step (1) of this embodiment) and hexamethylene diisocyanate (HDI, 30 parts by mass) were added to a reactor and prepolymerized at 75°C for 2.5 hours under nitrogen protection; then ethylenediamine (10 parts by mass), red iron oxide (10 parts by mass), wet-process sericite (8 parts by mass) and dimethylolpropionic acid (5 parts by mass) were added, and the temperature was raised to 80°C for chain extension reaction for 1.5 hours; triethylamine was added to neutralize to pH = 7, and high-speed emulsification was performed at 8000 rpm at room temperature for 30 minutes, and deionized water was added to adjust the solid content to 40%, thereby preparing a heavy-duty anti-corrosion coating.

[0132] Example 12

[0133] (1) Preparation of bio-based polyols

[0134] Epoxidized soybean oil (epoxy value 6.5%) is recorded as the first mixed solution; indole-4-carboxylic acid, 48 wt%~50 wt% tetrafluoroboric acid aqueous solution and DMSO are mixed to obtain a second mixed solution.

[0135] The first mixed liquid and the second mixed liquid were pumped into the microfluidic reactor (channel diameter 1.0 mm, inner wall treated with perfluoroalkylsilane hydrophobic coating, volume 90 mL) of the microfluidic reactor device for ring-opening reaction, the reaction temperature was controlled to be 95℃, the reaction pressure was controlled to be 0.4 MPa, and the reaction residence time of the ring-opening reaction in the microfluidic reactor was 10min. In the process of the reaction, the flow rate of the first mixed liquid and the second mixed liquid was adjusted to control the molar ratio of the epoxy group in the epoxidized soybean oil to the carboxylic acid group in the indole-4-carboxylic acid to be 1:1.5, and the mass of tetrafluoroboric acid accounted for 1.0% of the total mass of the epoxidized soybean oil and indole-4-carboxylic acid. After the reaction, the reaction liquid was extracted with a saturated sodium carbonate aqueous solution, washed with distilled water to neutrality, then dried with anhydrous sodium sulfate to remove water, and then removed the unreacted carboxylic acid by reduced pressure distillation (80℃, -0.09 MPa), and then purified by activated carbon adsorption (the amount of activated carbon was 5% of the product mass) to obtain a light brown transparent liquid, that is, bio-based polyol.

[0136] The bio-based polyol prepared in this example has a hydroxyl value of 205 mg KOH / g (titration method GB / T12008.3-2009) and a viscosity of 690 mPa·s (25° C., measured by a rotational viscometer).

[0137] (2) Preparation of heavy-duty anti-corrosion coatings

[0138] Bio-based polyol (55 parts by mass, prepared in step (1) of this embodiment) and hexamethylene diisocyanate (HDI, 30 parts by mass) were added to a reactor and prepolymerized at 75°C for 2.5 hours under nitrogen protection; then ethylenediamine (8 parts by mass), red iron oxide (10 parts by mass), wet-process sericite (6 parts by mass) and dimethylolpropionic acid (4 parts by mass) were added, and the temperature was raised to 80°C for chain extension reaction for 1.5 hours; triethylamine was added to neutralize to pH = 7, and high-speed emulsification was performed at 8000 rpm at room temperature for 30 minutes, and deionized water was added to adjust the solid content to 40%, thereby preparing a heavy-duty anti-corrosion coating.

[0139] Embodiment 13

[0140] (1) Preparation of bio-based polyols

[0141] Epoxidized soybean oil (epoxy value 6.5%) is recorded as the first mixed liquid; trimethylpyruvic acid, 48 wt%~50 wt% tetrafluoroboric acid aqueous solution and DMSO are mixed to obtain a second mixed liquid.

[0142] The first mixed liquid and the second mixed liquid were pumped into the microfluidic reactor (channel diameter 1.0 mm, inner wall treated with perfluoroalkylsilane hydrophobic coating, volume 96 mL) of the microfluidic reactor device for ring-opening reaction, the reaction temperature was controlled to be 100℃, the reaction pressure was controlled to be 0.5 MPa, and the reaction residence time of the ring-opening reaction in the microfluidic reactor was 12min. In the process of the reaction, the flow rate of the first mixed liquid and the second mixed liquid was adjusted to control the molar ratio of the epoxy group in the epoxidized soybean oil to the carboxylic acid group in the trimethyl pyruvic acid to be 1:1.5, and the mass of tetrafluoroboric acid accounted for 1.0% of the total mass of the epoxidized soybean oil and trimethyl pyruvic acid. After the reaction, the reaction liquid was extracted with a saturated sodium carbonate aqueous solution, washed with distilled water to neutrality, then dried with anhydrous sodium sulfate to remove water, and then removed the unreacted carboxylic acid by reduced pressure distillation (80℃, -0.09 MPa), and then purified by activated carbon adsorption (the amount of activated carbon was 5% of the product mass) to obtain a light yellow transparent liquid, that is, bio-based polyol.

[0143] The bio-based polyol prepared in this example has a hydroxyl value of 185 mg KOH / g (titration method GB / T12008.3-2009) and a viscosity of 760 mPa·s (25° C., measured by a rotational viscometer).

[0144] (2) Preparation of heavy-duty anti-corrosion coatings

[0145] Bio-based polyol (55 parts by mass, prepared in step (1) of this embodiment) and hexamethylene diisocyanate (HDI, 30 parts by mass) were added to a reactor and prepolymerized at 75°C for 2.5 hours under nitrogen protection; then ethylenediamine (8 parts by mass), red iron oxide (10 parts by mass), wet-process sericite (6 parts by mass) and dimethylolpropionic acid (4 parts by mass) were added, and the temperature was raised to 80°C for chain extension reaction for 1.5 hours; triethylamine was added to neutralize to pH = 7, and high-speed emulsification was performed at 8000 rpm at room temperature for 30 minutes, and deionized water was added to adjust the solid content to 40%, thereby preparing a heavy-duty anti-corrosion coating.

[0146] Embodiment 14

[0147] Epoxidized soybean oil (epoxy value 6.5%) is recorded as the first mixed solution; 2-picolinic acid, 48 wt%~50 wt% tetrafluoroboric acid aqueous solution and DMSO are mixed to obtain a second mixed solution.

[0148] The first mixed liquid and the second mixed liquid were pumped into the microfluidic reactor (channel diameter 1.0 mm, inner wall treated with perfluoroalkylsilane hydrophobic coating, volume 84 mL) of the microfluidic reactor device for ring-opening reaction, the reaction temperature was controlled to 95℃, the reaction pressure was controlled to 0.4 MPa, and the reaction residence time of the ring-opening reaction in the microfluidic reactor was 10min. In the process of the reaction, the flow rate of the first mixed liquid and the second mixed liquid was adjusted to control the molar ratio of the epoxy group in the epoxidized soybean oil to the carboxylic acid group in the 2-pyridine carboxylic acid to be 1:1.5. After the reaction, the reaction liquid was extracted with a saturated sodium carbonate aqueous solution, washed with distilled water to neutrality, then dried with anhydrous sodium sulfate to remove water, and then distilled under reduced pressure (80℃, -0.09 MPa) to remove the unreacted carboxylic acid, and then purified by activated carbon adsorption (the amount of activated carbon was 5% of the product mass) to obtain a light yellow transparent liquid, that is, bio-based polyol.

[0149] The ratio of the mass of tetrafluoroboric acid to the total mass of epoxidized soybean oil and 2-pyridinecarboxylic acid was changed, and the mass of tetrafluoroboric acid accounted for 0%, 0.5%, 1.0%, 2.0% and 3.0% of the total mass of epoxidized soybean oil and 2-pyridinecarboxylic acid, respectively. After the reaction, the epoxy value in the bio-based polyol was determined. The specific results are shown in Figure 2 .

[0150] The experimental results show that as the amount of tetrafluoroboric acid increases, the epoxy value of the reaction product bio-based polyol decreases rapidly. However, when the amount of tetrafluoroboric acid is 1.0wt%, the epoxy value of the reaction product bio-based polyol remains almost unchanged if the amount of tetrafluoroboric acid is further increased. Therefore, the optimal amount of tetrafluoroboric acid is 1.0wt%.

[0151] Comparative Example 1

[0152] The ring-opening reagent is a traditional alcohol (ethylene glycol), and the reaction apparatus is a conventional reaction bottle.

[0153] (1) Preparation of bio-based polyols

[0154] Epoxidized soybean oil (epoxy value 6.5%, 20 g), ethylene glycol (the molar ratio of epoxy groups in epoxidized soybean oil to hydroxyl groups in ethylene glycol is 1:1.3), and p-toluenesulfonic acid (the amount is 1.0% of the total mass of epoxidized soybean oil and ethylene glycol) were added into a three-necked flask, heated to 120℃ under stirring, and the reaction time was 4 h. After the reaction, the product was extracted with a saturated sodium carbonate aqueous solution, washed with distilled water until neutral, then dried over anhydrous sodium sulfate to remove water, and then vacuum distilled (80℃, -0.09MPa) to remove unreacted reagents, and then purified by activated carbon adsorption to obtain bio-based polyols. The hydroxyl value was measured to be 155 mg KOH / g (titration method GB / T 12008.3-2009), and the viscosity was 2500 mPa·s (25℃, measured by rotational viscometer).

[0155] (2) Preparation of heavy-duty anti-corrosion coatings

[0156] Bio-based polyol (55 parts by mass, prepared in step (1) of this embodiment) and hexamethylene diisocyanate (HDI, 30 parts by mass) were added to a reactor and prepolymerized at 75°C for 2.5 hours under nitrogen protection; then ethylenediamine (8 parts by mass), red iron oxide (10 parts by mass), wet-process sericite (6 parts by mass) and dimethylolpropionic acid (4 parts by mass) were added, and the temperature was raised to 80°C for chain extension reaction for 1.5 hours; triethylamine was added to neutralize to pH = 7, and high-speed emulsification was performed at 8000 rpm at room temperature for 30 minutes, and deionized water was added to adjust the solid content to 40%, thereby preparing a heavy-duty anti-corrosion coating.

[0157] Comparative Example 2

[0158] The ring-opening reagent is a conventional carboxylic acid (acetic acid), and the reaction apparatus is a conventional reaction bottle.

[0159] (1) Preparation of bio-based polyols

[0160] Epoxidized soybean oil (epoxy value 6.5%, 20 g), acetic acid (the molar ratio of epoxy groups in epoxidized soybean oil to carboxylic acid groups in acetic acid is 1:1.5), and p-toluenesulfonic acid (the amount is 0.15% of the total mass of epoxidized soybean oil and acetic acid) were added into a batch reactor, the temperature was controlled at 95℃, and the reaction was stirred for 3 hours. After the reaction, the reaction solution was extracted with a saturated sodium carbonate aqueous solution, washed with distilled water until neutral, and then dried over anhydrous sodium sulfate to remove water, and then the unreacted carboxylic acid was removed by reduced pressure distillation (80℃, -0.09 MPa), and then purified by activated carbon adsorption (the amount of activated carbon was 5% of the mass of the product) to obtain bio-based polyols, with a hydroxyl value of 135 mg KOH / g (titration method GB / T 12008.3-2009) and a viscosity of 2200 mPa·s (25℃, measured by a rotational viscometer).

[0161] (2) Preparation of heavy-duty anti-corrosion coatings

[0162] Bio-based polyol (55 parts by mass, prepared in step (1) of this embodiment) and hexamethylene diisocyanate (HDI, 30 parts by mass) were added to a reactor and prepolymerized at 75°C for 2.5 hours under nitrogen protection; then ethylenediamine (8 parts by mass), red iron oxide (10 parts by mass), wet-process sericite (6 parts by mass) and dimethylolpropionic acid (4 parts by mass) were added, and the temperature was raised to 80°C for chain extension reaction for 1.5 hours; triethylamine was added to neutralize to pH = 7, and high-speed emulsification was performed at 8000 rpm at room temperature for 30 minutes, and deionized water was added to adjust the solid content to 40%, thereby preparing a heavy-duty anti-corrosion coating.

[0163] Comparative Example 3

[0164] The same raw materials and proportions as those in Example 1 were used, except that a conventional reaction apparatus (three-necked flask) was used.

[0165] (1) Preparation of bio-based polyols

[0166] Epoxidized soybean oil (epoxy value 6.5%, 20 g) was mixed with 2-ethylhexanoic acid (liquid) and 48 wt%~50 wt% tetrafluoroboric acid aqueous solution and added into a three-necked flask (the molar ratio of epoxy groups in epoxidized soybean oil to carboxylic acid groups in 2-ethylhexanoic acid was 1:1.3, and the mass of tetrafluoroboric acid accounted for 1.0% of the total mass of epoxidized soybean oil and 2-ethylhexanoic acid). The temperature was raised to 85°C under stirring, and the reaction time was extended to 3 hours (to compensate for the insufficient mass transfer efficiency of conventional reaction equipment). After the reaction, the reaction solution was extracted with a saturated sodium carbonate aqueous solution, washed with distilled water until neutral, and then dried over anhydrous sodium sulfate to remove water. Unreacted carboxylic acid was removed by reduced pressure distillation (80°C, -0.09 MPa), and then purified by activated carbon adsorption (the amount of activated carbon was 5% of the product mass) to obtain bio-based polyols. The hydroxyl value was measured to be 170 mg KOH / g (titration method GB / T 12008.3-2009), and the viscosity was 2100 mPa·s (25°C, measured by rotational viscometer).

[0167] (2) Preparation of heavy-duty anti-corrosion coatings

[0168] Bio-based polyol (55 parts by mass, prepared in step (1) of this embodiment) and hexamethylene diisocyanate (HDI, 30 parts by mass) were added to a reactor and prepolymerized at 75°C for 2.5 hours under nitrogen protection; then ethylenediamine (8 parts by mass), red iron oxide (10 parts by mass), wet-process sericite (6 parts by mass) and dimethylolpropionic acid (4 parts by mass) were added, and the temperature was raised to 80°C for chain extension reaction for 1.5 hours; triethylamine was added to neutralize to pH = 7, and high-speed emulsification was performed at 8000 rpm at room temperature for 30 minutes, and deionized water was added to adjust the solid content to 40%, thereby preparing a heavy-duty anti-corrosion coating.

[0169] Embodiment 15

[0170] The bio-based polyols and heavy-duty anti-corrosion coatings prepared in Examples 1 to 13 and Comparative Examples 1 to 3 were subjected to performance tests. The bio-based polyols were tested for hydroxyl value (GB / T 12008.3-2009) and viscosity (GB / T22235-2008). The heavy-duty anti-corrosion coatings were tested for tensile strength (GB / T 528-2009), salt spray resistance (GB / T 10125-2021), crosslinking density (ASTM D2765-2016), elongation at break (GB / T 528-2009), pencil hardness (GB / T 6739-2022), Taber abrasion (GB / T 1768-2006), water resistance (GB / T 1733-1993), and chemical corrosion resistance (GB / T9274-1988). The specific experimental results are shown in Tables 1, 2, and 3.

[0171] Table 1

[0172] .

[0173] Table 2

[0174] .

[0175] Table 3

[0176] .

[0177] As shown in Tables 1, 2 and 3, the present invention combines microfluidic technology with specific carboxylic acid ring-opening reagents (such as those containing ester bonds, heterocyclic structures, etc.). The microfluidic technology significantly shortens the reaction time to 8-15 minutes, and the hydroxyl value of the bio-based polyol obtained reaches 185-210 mg KOH / g, the viscosity is ≤760 mPa·s, and the coating is endowed with a high crosslinking density (7.0×10⁻ 4 mol / cm³~10.1×10⁻ 4 mol / cm³), excellent salt spray resistance (≥800 h), pencil hardness (2H~4H) and chemical corrosion resistance (alkali / acid / oil resistance, etc.), surpassing the effect of traditional alcohols or ordinary structure carboxylic acids as ring-opening reagents, and realizing efficient, environmentally friendly and high-performance heavy-duty anti-corrosion coating preparation.

[0178] The present invention provides a bio-based polyol and a preparation method thereof and a method for its application in heavy-duty anticorrosion coatings. There are many methods and approaches to implement the technical solution. The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention. All components not specified in this embodiment can be implemented using existing technologies.

Claims

1. A method for preparing a bio-based polyol, characterized in that: The epoxidized vegetable oil is recorded as the first mixed liquid; the carboxylic acid ring-opening reagent is mixed with the catalyst to obtain a second mixed liquid; the first mixed liquid and the second mixed liquid are respectively pumped into the microfluidic reactor of the microfluidic reactor device to perform a ring-opening reaction, and after the reaction is completed, the bio-based polyol is obtained by post-treatment; Wherein, the carboxylic acid ring-opening reagent is any one or a combination of 2-ethylhexanoic acid, 3,4-diethoxybenzoic acid, 3-indolecarboxylic acid, 2-cyclohexenecarboxylic acid, phenylpyruvic acid, levulinic acid, cyclohexanecarboxylic acid, 3-(3-ethylcyclopentyl)propionic acid, 3-ethoxypropionic acid, 2-hydroxybenzoic acid, 2-pyridinecarboxylic acid, indole-4-carboxylic acid and trimethylpyruvic acid; The hydroxyl value of the bio-based polyol is 170-210 mg KOH / g; and the viscosity of the bio-based polyol is less than or equal to 800 mPa·s (25° C.).

2. The preparation method according to claim 1, characterized in that: The epoxidized vegetable oil is any one of epoxidized soybean oil, epoxidized castor oil, epoxidized linseed oil, epoxidized rapeseed oil and epoxidized sunflower oil, or a combination thereof; or, the catalyst is any one of tetrafluoroboric acid, sulfuric acid, phosphoric acid, p-toluenesulfonic acid and methanesulfonic acid, or a combination thereof; or, when the carboxylic acid ring-opening reagent is a liquid, the carboxylic acid ring-opening reagent is mixed with the catalyst to obtain a second mixed liquid; or, when the carboxylic acid ring-opening reagent is a solid, the carboxylic acid ring-opening reagent is mixed with the catalyst and a solvent to obtain a second mixed liquid; or, the solvent is any one of dimethyl sulfoxide, N,N-dimethylformamide, tetrahydrofuran and acetonitrile, or a combination thereof.

3. The preparation method according to claim 1, characterized in that: During the ring-opening reaction, the molar ratio of the epoxy group in the epoxidized vegetable oil to the carboxyl group in the carboxylic acid ring-opening reagent is 1:(1.3~1.6); or, during the ring-opening reaction, the catalyst accounts for 0.5%~3.0% of the total mass of the epoxidized vegetable oil and the carboxylic acid ring-opening reagent; or, the reaction temperature of the ring-opening reaction is 70℃~120℃; or, the reaction pressure of the ring-opening reaction is 0.2 MPa~0.6MPa; or, the reaction residence time of the ring-opening reaction is 5 min~15 min; or, the microfluidic field reaction device includes a connecting pipe, a first feed pump, a second feed pump, a micromixer, a microfluidic field reactor and a receiver, wherein the first feed pump and the second feed pump are connected to the micromixer in parallel through a connecting pipe, and the micromixer, the microfluidic field reactor and the receiver are connected in series in sequence through a connecting pipe.

4. The bio-based polyol prepared by the preparation method according to any one of claims 1 to 3.

5. Use of the bio-based polyol according to claim 4 in the preparation of heavy-duty anti-corrosion coatings.

6. A heavy-duty anticorrosive coating, characterized in that: The composition comprises the following components in parts by weight: 50-60 parts of the bio-based polyol according to claim 4; Isocyanate, 25-35 parts; Chain extender, 6-10 parts; Anti-rust pigment, 8-12 parts; Corrosion-resistant filler, 4 to 8 parts; Hydrophilic chain extender, 2~6 parts.

7. The heavy-duty anticorrosion coating according to claim 6, characterized in that: The isocyanate is hexamethylene diisocyanate or isophorone diisocyanate; or, the chain extender is any one of ethylenediamine, diethylenetriamine and isophoronediamine, or a combination of several of them; or, the anti-rust pigment is any one of red iron oxide, mica iron oxide, iron tannate and aluminum tripolyphosphate, or a combination of several of them; or, the corrosion-resistant filler is any one of wet-process sericite, titanium dioxide and barite powder, or a combination of several of them; or, the hydrophilic chain extender is any one of dihydroxymethylpropionic acid, dihydroxymethylbutyric acid and sodium ethylenediamine sulfonate, or a combination of several of them.

8. The method for preparing the heavy-duty anticorrosive coating according to claim 6, characterized in that: The bio-based polyol described in claim 4 is mixed with isocyanate in parts by weight to carry out a prepolymerization reaction; then a chain extender, an anti-rust pigment, a corrosion-resistant filler, and a hydrophilic chain extender are added to carry out a chain extension reaction; finally, a base is added to adjust the pH to neutral, emulsified, and deionized water is added to adjust the solid content to obtain a heavy-duty anti-corrosion coating.

9. The preparation method according to claim 8, characterized in that: The isocyanate is hexamethylene diisocyanate or isophorone diisocyanate; or, the chain extender is any one of ethylenediamine, diethylenetriamine and isophoronediamine or a combination of several thereof; or, the anti-rust pigment is any one of iron oxide red, mica iron oxide, iron tannate and aluminum tripolyphosphate or a combination of several thereof; or, the corrosion-resistant filler is any one of wet-process sericite, titanium dioxide and barite powder or a combination of several thereof; or, the hydrophilic chain extender is any one of dihydroxymethylpropionic acid, dihydroxymethylbutyric acid and sodium ethylenediamine ethanesulfonate. or, the base is any one of triethylamine, dimethylethanolamine and triethanolamine or a combination of several thereof; or, the prepolymerization reaction has a reaction temperature of 75-80°C; or, the prepolymerization reaction has a reaction time of 2-3 hours; or, the chain extension reaction has a reaction temperature of 75-85°C; or, the chain extension reaction has a reaction time of 1-2 hours; or, the emulsification is carried out at room temperature; or, the emulsification time is 20-40 minutes; or, the emulsification is carried out under centrifugation at a centrifugal speed of 6000-8000 rpm; or, deionized water is added to adjust the solid content to 40%-45%.

10. Use of the heavy-duty anti-corrosion coating according to claim 6 or the heavy-duty anti-corrosion coating prepared by the preparation method according to any one of claims 8 to 9 in the preparation of anti-corrosion materials.

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