Preparation method of a vegetable oil polyol and its application in a polyurethane anticorrosive coating

Abstract

The present invention discloses a preparation method of vegetable oil polyol and its application in polyurethane anticorrosive coatings. Epoxidized vegetable oil and an acidic catalyst are mixed into a first mixed solution; a 2,3-dihydroxysuccinic acid diester compound is dissolved in an organic solvent to obtain a second mixed solution; the first mixed solution and the second mixed solution are respectively pumped into a microreactor for a first ring-opening reaction to obtain a first reaction solution; a third mixed solution obtained by dissolving a long-chain hydroxy fatty acid ester in an organic solvent and the first reaction solution flow into the microreactor to continue a second ring-opening reaction to obtain a second reaction solution; the second reaction solution is subjected to simple post-treatment to obtain vegetable oil polyol. The present invention adopts a novel ring-opening reagent and a continuous microreaction process. The prepared vegetable oil polyol has a novel structure, a moderate molecular weight and a uniform distribution, and a moderate viscosity. It can replace traditional petrochemical polyols. The bio-based polyurethane coating prepared by the vegetable oil polyol of the present invention has strong anticorrosive performance.

Description

Technical Field

[0001] The present invention belongs to the field of chemical synthesis, and particularly relates to a vegetable oil polyol, a preparation method thereof, and an application thereof in an anticorrosive coating. Background Art

[0002] Polyurethane is a polymer with a repeating structural unit of urethane segments, which is made by reacting a polyol with an isocyanate. Polyurethane products are divided into two categories: foamed products and non-foamed products. Foamed products include soft, rigid, and semi-rigid polyurethane foam plastics; non-foamed products include coatings, adhesives, synthetic leather, elastomers, and elastic fibers, etc. One of the two types of monomers for polyurethane synthesis, isocyanate products, has relatively few varieties, mainly MDI, TDI, etc. The other type of monomer, polyol, has a wide variety, uneven quality, and diversified downstream applications, leaving room for further research.

[0003] In the vegetable oil structure, long-chain groups replace the repeating units of traditional petrochemical polyols such as polyethers or polyesters. The basic nucleus of triglyceride in the structure has a star-shaped spatial conformation, endowing more functional properties and application space for downstream polyurethanes. However, vegetable oil polyols often have performance defects. The main reason is that the reaction process is uncontrollable. During the functional group conversion process, multiple epoxy groups and ester groups often participate in multiple side reaction processes. Therefore, it is difficult to construct the designed molecular structure by traditional chemical methods, which greatly limits the quality of polyols. It often needs to be mixed with traditional petrochemical polyols to have a certain application effect. Through reaction mechanism analysis, the main reason is that oil esters often have poor miscibility with reaction reagents, but the reaction activity is relatively low, resulting in the need for long-term high-intensity reactions. However, due to the influence of multiple functional groups in the structure, it is difficult to balance reaction selectivity and conversion rate, and the process controllability is poor, resulting in poor molecular uniformity, high viscosity, and large differences between macroscopic indicators and microscopic indicators of single molecules of the obtained products. Therefore, even though the price of vegetable oil is often lower than that of monomers with petrochemical repeating units, it is difficult to obtain vegetable oil polyol products with advantages in both cost and quality. It is necessary to control the product quality through chemical process control. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for preparing vegetable oil polyol by using a microchannel reaction device to avoid cross-linking side reactions caused by non-selective ring-opening of secondary hydroxyl groups generated in the ring-opening reaction and other epoxy groups.

[0005] To solve the above technical problems, the present invention discloses a preparation method of vegetable oil polyol, comprising mixing epoxy vegetable oil and an acidic catalyst to form a first mixed solution; dissolving a 2,3-dihydroxysuccinic acid diester compound in an organic solvent to form a second mixed solution; respectively and simultaneously pumping the first mixed solution and the second mixed solution into a first microreactor of a microchannel reaction device to carry out a first ring-opening reaction to obtain a first reaction solution; simultaneously pumping a third mixed solution obtained by dissolving a long-chain hydroxy fatty acid ester in an organic solvent and the first reaction solution into a second microreactor of the microchannel reaction device to continue carrying out a second ring-opening reaction, and collecting the obtained reaction solution to obtain the product.

[0006] Among them, the epoxy vegetable oil is any one or a combination of several of epoxy olive oil, epoxy peanut oil, epoxy rapeseed oil, epoxy cottonseed oil, epoxy soybean oil, epoxy coconut oil, epoxy palm oil, epoxy sesame oil, epoxy corn oil, epoxy sunflower oil;

[0007] The acidic catalyst is any one or a combination of several of fluoboric acid, concentrated sulfuric acid, p-toluenesulfonic acid, methanesulfonic acid, benzenesulfonic acid;

[0008] The 2,3-dihydroxysuccinic acid diester compound is dimethyl 2,3-dihydroxysuccinate or diisobutyl 2,3-dihydroxysuccinate;

[0009] The organic solvent is any one or a combination of several of ethyl acetate, dichloromethane, dichloroethane, chloroform, n-hexane, tetrahydrofuran, 1,4-dioxane, carbon tetrachloride, toluene, xylene;

[0010] The long-chain hydroxy fatty acid ester is methyl 14-hydroxytetradecanoate and / or ethyl 14-hydroxytetradecanoate.

[0011] Specifically, the mass percentage of the acidic catalyst to the epoxy vegetable oil is 0.02-0.1%:1.

[0012] Specifically, in the second mixed solution, the mass-volume ratio of the 2,3-dihydroxysuccinic acid diester compound to the organic solvent is 1:0.5-2.

[0013] Specifically, in the third mixed solution, the mass-volume ratio of the long-chain hydroxy fatty acid ester to the organic solvent is 1:1-4.

[0014] Specifically, the reaction molar ratio of the epoxy group in the epoxy vegetable oil to the 2,3-dihydroxysuccinic acid diester compound is 1:0.7-0.8.

[0015] Specifically, the reaction molar ratio of the epoxy group in the epoxy vegetable oil to the long-chain hydroxy fatty acid ester is 1:0.1-0.2.

[0016] Specifically, the microchannel reaction device adopted in the present invention includes a first feed pump, a second feed pump, a third feed pump, a microreaction pipeline, a first micromixer, a second micromixer, a first microreactor, a second microreactor, and a receiver; the first feed pump and the second feed pump are connected to the first micromixer; the first reaction liquid and the third feed pump are connected to the second micromixer; wherein the micromixer, the microreactor, and the receiver are all connected in series through pipelines in sequence.

[0017] Among them, the micromixer is a conventional Y-type mixer or T-type mixer; the model of the microreactor is Vapotech, and it adopts a microstructured coaxial heat exchanger.

[0018] Specifically, the volumes of the first microreactor and the second microreactor are 5 mL to 20 mL.

[0019] Preferably, in the present invention, the reaction temperature of the first ring-opening reaction is 80 - 110 °C, and the reaction time is 3 - 15 min; the reaction temperature of the second ring-opening reaction is 80 - 110 °C, and the reaction time is 3 - 15 min.

[0020] Among them, the reaction effluent of the microreactor is separated, the organic phase is neutralized with acid, separated, dried, and rotary evaporated to obtain vegetable oil polyol.

[0021] Furthermore, the vegetable oil polyol prepared by the above preparation method is also within the protection scope of the present invention.

[0022] Even further, the application of the above-prepared vegetable oil polyol in the preparation of polyurethane coatings is also within the protection scope of the present invention.

[0023] Beneficial effects:

[0024] (1) The present invention uses a ring-opening reagent with a polyhydroxy and polyester group structure as the first ring-opening reagent to ensure an increase in functionality and easy regulation of the hydroxyl value. Through process control, the ring-opening reaction of most easily reactive epoxy groups is completed, and then a highly active long-chain hydroxy fatty acid ester is used to carry out the ring-opening reaction on the remaining epoxy groups with relatively weak reaction activity, obtaining a type of vegetable oil polyol product with an epoxy value residue of about 0.5 - 1. In order to avoid cross-linking side reactions caused by the non-selective ring-opening of the secondary hydroxyl groups generated in the ring-opening reaction with other epoxy groups, the inventor adopts microreaction technology and selects a microchannel reaction device as the reaction equipment to further control the ring-opening groups. In the prepared vegetable oil polyol, a polyester group is introduced, and a relatively high hydroxyl value is maintained while achieving a certain epoxy value residue, increasing the mechanical properties of the polyurethane material, maintaining a certain toughness of the polyurethane product, and having good anti-corrosion properties.

[0025] (2) The present invention adopts two specific types of ring-opening reagents for tandem reaction to prepare the vegetable oil polyol with novel structure. The polyol has moderate and uniform distribution and low viscosity, and can replace traditional petrochemical polyols. The polyurethane anti-corrosion coating prepared by the vegetable oil polyol prepared by the present invention has both strong mechanical properties and high toughness, and the comprehensive performance is significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] 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.

[0027] Figure 1 This is a schematic diagram of the microchannel reaction device used in the present invention. DETAILED DESCRIPTION

[0028] 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.

[0029] The relevant determination methods of the prepared vegetable oil polyol and polyurethane material of the present invention are as follows:

[0030] (1) The hydroxyl value is measured according to GB / T 12008.3-2009.

[0031] (2) Measure viscosity according to GB / T 12008.7-2010.

[0032] (3) Determine the surface drying time of the coating according to GB / T 1728-2020 (Method B).

[0033] (4) Determine the actual drying time of the coating according to GB / T 1728-1979 (Method A).

[0034] (5) VOC content was determined according to GB / T 23985-2009 (8.3).

[0035] (6) Measure the surface hardness of the coating according to GB / T 6739-2006.

[0036] (7) The impact resistance of the coating is determined according to GB / T 1732-2020.

[0037] (8) The flexibility of the coating was determined according to GB / T 1731-2020(4).

[0038] (9) Determine the coating adhesion according to GB / T 5210-2006.

[0039] (10) The neutral salt spray corrosion resistance test was determined according to GB / T 1771-2007.

[0040] Example 1

[0041] (1) Preparation of vegetable oil polyol: Epoxidized soybean oil (10 mL, epoxy value 6.2%, epoxy group 38.4 mmol) and boric acid fluoride (20 mg, 50%) were mixed to obtain a first mixed solution. Dimethyl 2,3-dihydroxysuccinate (5.13 g, 28.8 mmol) and ethyl acetate (10 mL) were mixed to obtain a second mixed solution. The temperature of the reactor was adjusted to 100 °C, and the first mixed solution and the second mixed solution were pumped into a 10 mL microreactor of a microchannel reaction device at a rate of 1 mL / min and 1.15 mL / min respectively for ring-opening reaction to obtain a first reaction solution. Methyl 14-hydroxytetradecanoate (1.47 g, 5.7 mmol) and ethyl acetate (20 mL) were mixed to obtain a third mixed solution. The temperature of the reactor was adjusted to 100 °C, and the third mixed solution was pumped into a 15 mL microreactor of the microchannel reaction device at a rate of 2 mL / min together with the first reaction solution for ring-opening reaction. The obtained reaction solution was washed successively with sodium bicarbonate solution (30 mL, 10%) and water (30 mL × 2). The organic phase was dried and concentrated to obtain soybean oil polyol with a hydroxyl value of 210 mg KOH / g, an epoxy value of 0.6, and a viscosity of 808 mPa·s.

[0042] (2) Preparation of vegetable oil-based polyurethane coating: A certain amount of vegetable oil polyol was mixed with isocyanate MDI (according to the molar ratio of NCO and OH functional groups of 1.25:1 - 1.05), and then a catalyst (3‰ of the mass of the polyol) was added, and the reaction was carried out for 2 hours to obtain a prepolymer mixed solution. A certain amount of hydrophilic chain extender and other additives were added to the prepolymer mixed solution, and the reaction was carried out for 3 hours to obtain a polymer mixed solution. An appropriate amount of neutralizer was added to neutralize the polymer mixed solution to neutral, and a diluent was added and emulsified by high-speed shearing to form a polyurethane emulsion. The substrate was a steel plate, which was sprayed once, and the dry film thickness was 60 - 80 microns. It was tested after being placed in the laboratory environment for 168 h.

[0043] Example 2

[0044] (1) Preparation of vegetable oil polyol: Epoxidized soybean oil (10 mL, epoxy value 6.2%, epoxy groups 38.4 mmol) and boric acid fluoride (20 mg, 50%) were mixed to obtain a first mixed solution. Dimethyl 2,3-dihydroxysuccinate (4.78 g, 26.9 mmol) and ethyl acetate (10 mL) were mixed to obtain a second mixed solution. The temperature of the reactor was adjusted to 100 °C, and the first and second mixed solutions were pumped into a microreactor with a volume of 10 mL in a microchannel reaction device at rates of 1 mL / min and 1.14 mL / min respectively for ring-opening reaction to obtain a first reaction solution. Methyl 14-hydroxytetradecanoate (1.99 g, 7.7 mmol) and ethyl acetate (20 mL) were mixed to obtain a third mixed solution. The temperature of the reactor was adjusted to 100 °C, and the third mixed solution was pumped into a microreactor with a volume of 15 mL in the microchannel reaction device at a rate of 2 mL / min together with the first reaction solution for ring-opening reaction. The resulting reaction solution was washed successively with sodium bicarbonate solution (30 mL, 10%) and water (30 mL × 2). The organic phase was dried and concentrated to obtain soybean oil polyol with a hydroxyl value of 205 mg KOH / g, an epoxy value of 0.7, and a viscosity of 692 mPa·s.

[0045] (2) Preparation of vegetable oil-based polyurethane coating: The polyurethane coating was prepared according to the general method in (2) of Example 1.

[0046] Example 3

[0047] (1) Preparation of vegetable oil polyol: Epoxidized soybean oil (10 mL, epoxy value 6.2%, epoxy groups 38.4 mmol) and boric acid fluoride (20 mg, 50%) were mixed to obtain a first mixed solution. Dimethyl 2,3-dihydroxysuccinate (5.47 g, 30.7 mmol) and ethyl acetate (10 mL) were mixed to obtain a second mixed solution. The temperature of the reactor was adjusted to 100 °C, and the first and second mixed solutions were pumped into a microreactor with a volume of 10 mL in a microchannel reaction device at rates of 1 mL / min and 1.16 mL / min respectively for ring-opening reaction to obtain a first reaction solution. Methyl 14-hydroxytetradecanoate (1.03 g, 4.0 mmol) and ethyl acetate (20 mL) were mixed to obtain a third mixed solution. The temperature of the reactor was adjusted to 100 °C, and the third mixed solution was pumped into a microreactor with a volume of 15 mL in the microchannel reaction device at a rate of 2 mL / min together with the first reaction solution for ring-opening reaction. The resulting reaction solution was washed successively with sodium bicarbonate solution (30 mL, 10%) and water (30 mL × 2). The organic phase was dried and concentrated to obtain soybean oil polyol with a hydroxyl value of 220 mg KOH / g, an epoxy value of 0.6, and a viscosity of 1026 mPa·s.

[0048] (2) Preparation of vegetable oil-based polyurethane coating: The polyurethane coating was prepared according to the general method in (2) of Example 1.

[0049] Example 4

[0050] (1) Preparation of vegetable oil polyol: Epoxidized soybean oil (10 mL, epoxy value 6.2%, epoxy groups 38.4 mmol) and boric acid fluoride (20 mg, 50%) were mixed to obtain a first mixed solution. Dimethyl 2,3-dihydroxysuccinate (4.78 g, 26.9 mmol) and ethyl acetate (10 mL) were mixed to obtain a second mixed solution. The reactor temperature was adjusted to 100 °C, and the first and second mixed solutions were pumped into a 10 mL microreactor of a microchannel reaction device at rates of 1 mL / min and 1.14 mL / min respectively for ring-opening reaction to obtain a first reaction solution. Methyl 14-hydroxytetradecanoate (1.47 g, 5.7 mmol) and ethyl acetate (20 mL) were mixed to obtain a third mixed solution. The reactor temperature was adjusted to 100 °C, and the third mixed solution was pumped into a 15 mL microreactor of the microchannel reaction device at a rate of 2 mL / min together with the first reaction solution for ring-opening reaction. The resulting reaction solution was washed successively with sodium bicarbonate solution (30 mL, 10%) and water (30 mL × 2). The organic phase was dried and concentrated to obtain soybean oil polyol with a hydroxyl value of 203 mg KOH / g, an epoxy value of 0.8, and a viscosity of 653 mPa·s.

[0051] (2) Preparation of vegetable oil-based polyurethane coating: The polyurethane coating was prepared according to the general method in (2) of Example 1.

[0052] Example 5

[0053] (1) Preparation of vegetable oil polyol: Epoxidized soybean oil (10 mL, epoxy value 6.2%, epoxy groups 38.4 mmol) and boric acid fluoride (20 mg, 50%) were mixed to obtain a first mixed solution. Dimethyl 2,3-dihydroxysuccinate (5.47 g, 30.7 mmol) and ethyl acetate (10 mL) were mixed to obtain a second mixed solution. The reactor temperature was adjusted to 100 °C, and the first and second mixed solutions were pumped into a 10 mL microreactor of a microchannel reaction device at rates of 1 mL / min and 1.16 mL / min respectively for ring-opening reaction to obtain a first reaction solution. Methyl 14-hydroxytetradecanoate (1.99 g, 7.7 mmol) and ethyl acetate (20 mL) were mixed to obtain a third mixed solution. The reactor temperature was adjusted to 100 °C, and the third mixed solution was pumped into a 15 mL microreactor of the microchannel reaction device at a rate of 2 mL / min together with the first reaction solution for ring-opening reaction. The resulting reaction solution was washed successively with sodium bicarbonate solution (30 mL, 10%) and water (30 mL × 2). The organic phase was dried and concentrated to obtain soybean oil polyol with a hydroxyl value of 218 mg KOH / g, an epoxy value of 0.5, and a viscosity of 988 mPa·s.

[0054] (2) Preparation of vegetable oil-based polyurethane coating: Prepare the polyurethane coating according to the general method in (2) of Example 1.

[0055] Example 6

[0056] (1) Preparation of vegetable oil polyol: Epoxidized soybean oil (10 mL, epoxy value 6.2%, epoxy group 38.4 mmol) and boric acid fluoride (20 mg, 50%) were mixed to obtain a first mixed solution. Dimethyl 2,3-dihydroxysuccinate (5.13 g, 28.8 mmol) and ethyl acetate (10 mL) were mixed to obtain a second mixed solution. The temperature of the reactor was adjusted to 80 °C, and the first mixed solution and the second mixed solution were respectively pumped into a microreactor with a volume of 10 mL in a microchannel reaction device at a rate of 1 mL / min and 1.15 mL / min for ring-opening reaction to obtain a first reaction solution. Methyl 14-hydroxytetradecanoate (1.47 g, 5.7 mmol) and ethyl acetate (20 mL) were mixed to obtain a third mixed solution. The temperature of the reactor was adjusted to 80 °C, and the third mixed solution was pumped into a microreactor with a volume of 15 mL in the microchannel reaction device at a rate of 2 mL / min together with the first reaction solution for ring-opening reaction. The obtained reaction solution was washed successively with sodium bicarbonate solution (30 mL, 10%) and water (30 mL × 2). The organic phase was dried and concentrated to obtain soybean oil polyol with a hydroxyl value of 201 mg KOH / g, an epoxy value of 0.9, and a viscosity of 628 mPa·s.

[0057] (2) Preparation of vegetable oil-based polyurethane coating: Prepare the polyurethane coating according to the general method in (2) of Example 1.

[0058] Example 7

[0059] (1) Preparation of vegetable oil polyol: Epoxidized soybean oil (10 mL, epoxy value 6.2%, epoxy group 38.4 mmol) and boric acid fluoride (20 mg, 50%) were mixed to obtain a first mixed solution. Dimethyl 2,3-dihydroxysuccinate (5.13 g, 28.8 mmol) and ethyl acetate (10 mL) were mixed to obtain a second mixed solution. The temperature of the reactor was adjusted to 110 °C, and the first mixed solution and the second mixed solution were respectively pumped into a microreactor with a volume of 10 mL in a microchannel reaction device at a rate of 1 mL / min and 1.15 mL / min for ring-opening reaction to obtain a first reaction solution. Methyl 14-hydroxytetradecanoate (1.47 g, 5.7 mmol) and ethyl acetate (20 mL) were mixed to obtain a third mixed solution. The temperature of the reactor was adjusted to 110 °C, and the third mixed solution was pumped into the microreactor with a volume of 15 mL in the microchannel reaction device at a rate of 2 mL / min together with the first reaction solution for ring-opening reaction. The obtained reaction solution was washed successively with sodium bicarbonate solution (30 mL, 10%) and water (30 mL × 2). The organic phase was dried and concentrated to obtain soybean oil polyol with a hydroxyl value of 208 mg KOH / g, an epoxy value of 0.7, and a viscosity of 784 mPa·s.

[0060] (2) Preparation of vegetable oil-based polyurethane coating: The polyurethane coating was prepared according to the general method in (2) of Example 1.

[0061] Example 8

[0062] (1) Preparation of vegetable oil polyol: Epoxidized soybean oil (10 mL, epoxy value 6.2%, epoxy group 38.4 mmol) and boric acid fluoride (20 mg, 50%) were mixed to obtain a first mixed solution. Dimethyl 2,3-dihydroxysuccinate (5.13 g, 28.8 mmol) and ethyl acetate (10 mL) were mixed to obtain a second mixed solution. The temperature of the reactor was adjusted to 100 °C, and the first mixed solution and the second mixed solution were respectively pumped into a microreactor with a volume of 10 mL in a microchannel reaction device at a rate of 2 mL / min and 2.3 mL / min for ring-opening reaction to obtain a first reaction solution. Methyl 14-hydroxytetradecanoate (1.47 g, 5.7 mmol) and ethyl acetate (20 mL) were mixed to obtain a third mixed solution. The temperature of the reactor was adjusted to 100 °C, and the third mixed solution was pumped into the microreactor with a volume of 20 mL in the microchannel reaction device at a rate of 4 mL / min together with the first reaction solution for ring-opening reaction. The obtained reaction solution was washed successively with sodium bicarbonate solution (30 mL, 10%) and water (30 mL × 2). The organic phase was dried and concentrated to obtain soybean oil polyol with a hydroxyl value of 200 mg KOH / g, an epoxy value of 1, and a viscosity of 576 mPa·s.

[0063] (2) Preparation of vegetable oil-based polyurethane coating: The polyurethane coating was prepared according to the general method in (2) of Example 1.

[0064] Example 9

[0065] (1) Preparation of vegetable oil polyol: Epoxidized soybean oil (10 mL, epoxy value 6.2%, epoxy groups 38.4 mmol) and boric acid fluoride (20 mg, 50%) were mixed to obtain a first mixed solution, dimethyl 2,3-dihydroxysuccinate (5.13 g, 28.8 mmol) and ethyl acetate (10 mL) were mixed to obtain a second mixed solution. The reactor temperature was adjusted to 100 °C, and the first mixed solution and the second mixed solution were pumped into a 10 mL microreactor of a microchannel reaction device at rates of 0.5 mL / min and 0.58 mL / min respectively for ring-opening reaction to obtain a first reaction solution; methyl 14-hydroxytetradecanoate (1.47 g, 5.7 mmol) and ethyl acetate (20 mL) were mixed to obtain a third mixed solution. The reactor temperature was adjusted to 100 °C, and the third mixed solution was pumped into a 15 mL microreactor of the microchannel reaction device at a rate of 1 mL / min together with the first reaction solution for ring-opening reaction. The obtained reaction solution was washed successively with sodium bicarbonate solution (30 mL, 10%) and water (30 mL × 2). The organic phase was dried and concentrated to obtain soybean oil polyol with a hydroxyl value of 207 mg KOH / g, an epoxy value of 0.5, and a viscosity of 792 mPa·s.

[0066] (2) Preparation of vegetable oil-based polyurethane coating: The polyurethane coating was prepared according to the general method in (2) of Example 1.

[0067] Example 10

[0068] (1) Preparation of vegetable oil polyol: Epoxidized soybean oil (10 mL, epoxy value 6.2%, epoxy groups 38.4 mmol) and boric acid fluoride (20 mg, 50%) were mixed to obtain a first mixed solution, diisobutyl 2,3-dihydroxysuccinate (7.55 g, 28.8 mmol) and ethyl acetate (10 mL) were mixed to obtain a second mixed solution. The reactor temperature was adjusted to 100 °C, and the first mixed solution and the second mixed solution were pumped into a 10 mL microreactor of a microchannel reaction device at rates of 1 mL / min and 1.16 mL / min respectively for ring-opening reaction to obtain a first reaction solution; methyl 14-hydroxytetradecanoate (1.47 g, 5.7 mmol) and ethyl acetate (20 mL) were mixed to obtain a third mixed solution. The reactor temperature was adjusted to 100 °C, and the third mixed solution was pumped into a 15 mL microreactor of the microchannel reaction device at a rate of 2 mL / min together with the first reaction solution for ring-opening reaction. The obtained reaction solution was washed successively with sodium bicarbonate solution (30 mL, 10%) and water (30 mL × 2). The organic phase was dried and concentrated to obtain soybean oil polyol with a hydroxyl value of 185 mg KOH / g, an epoxy value of 0.6, and a viscosity of 558 mPa·s.

[0069] (2) Preparation of vegetable oil-based polyurethane coating: Prepare the polyurethane coating according to the general method in (2) of Example 1.

[0070] Example 11

[0071] (1) Preparation of vegetable oil polyol: Epoxidized soybean oil (10 mL, epoxy value 6.2%, epoxy group 38.4 mmol) and boric acid fluoride (20 mg, 50%) were mixed to obtain a first mixed solution, dimethyl 2,3-dihydroxysuccinate (5.13 g, 28.8 mmol) and ethyl acetate (10 mL) were mixed to obtain a second mixed solution. The temperature of the reactor was adjusted to 100 °C, and the first mixed solution and the second mixed solution were pumped into a microreactor with a volume of 10 mL in a microchannel reaction device at a rate of 1 mL / min and 1.15 mL / min respectively for ring-opening reaction to obtain a first reaction solution; ethyl 14-hydroxytetradecanoate (1.55 g, 5.7 mmol) and ethyl acetate (20 mL) were mixed to obtain a third mixed solution. The temperature of the reactor was adjusted to 100 °C, and the third mixed solution was pumped into a microreactor with a volume of 15 mL in the microchannel reaction device at a rate of 2 mL / min together with the first reaction solution for ring-opening reaction. The obtained reaction solution was washed successively with sodium bicarbonate solution (30 mL, 10%) and water (30 mL × 2). The organic phase was dried and concentrated to obtain soybean oil polyol with a hydroxyl value of 211 mg KOH / g, an epoxy value of 0.7, and a viscosity of 853 mPa·s.

[0072] (2) Preparation of vegetable oil-based polyurethane coating: Prepare the polyurethane coating according to the general method in (2) of Example 1.

[0073] Example 12

[0074] (1) Preparation of vegetable oil polyol: Epoxy cottonseed oil (13 mL, epoxy value 5.1%, epoxy groups 38.4 mmol) and boric acid fluoride (20 mg, 50%) were mixed to obtain a first mixed solution. Dimethyl 2,3-dihydroxysuccinate (5.13 g, 28.8 mmol) and ethyl acetate (10 mL) were mixed to obtain a second mixed solution. The temperature of the reactor was adjusted to 100 °C, and the first mixed solution and the second mixed solution were respectively pumped into a microreactor with a volume of 10 mL in a microchannel reaction device at a rate of 1.3 mL / min and 1.15 mL / min for ring-opening reaction to obtain a first reaction solution. Methyl 14-hydroxytetradecanoate (1.47 g, 5.7 mmol) and ethyl acetate (20 mL) were mixed to obtain a third mixed solution. The temperature of the reactor was adjusted to 100 °C, and the third mixed solution was pumped into the microreactor with a volume of 15 mL in the microchannel reaction device at a rate of 2 mL / min together with the first reaction solution for ring-opening reaction. The obtained reaction solution was successively washed with sodium bicarbonate solution (30 mL, 10%) and water (30 mL × 2). The organic phase was dried and concentrated to obtain soybean oil polyol with a hydroxyl value of 188 mg KOH / g, an epoxy value of 0.6, and a viscosity of 789 mPa·s.

[0075] (2) Preparation of vegetable oil-based polyurethane coating: The polyurethane coating was prepared according to the general method in (2) of Example 1.

[0076] Example 13

[0077] (1) Preparation of vegetable oil polyol: Epoxy sunflower oil (10 mL, epoxy value 6.0%, epoxy groups 38.2 mmol) and boric acid fluoride (20 mg, 50%) were mixed to obtain a first mixed solution. Dimethyl 2,3-dihydroxysuccinate (5.13 g, 28.8 mmol) and ethyl acetate (10 mL) were mixed to obtain a second mixed solution. The temperature of the reactor was adjusted to 100 °C, and the first mixed solution and the second mixed solution were respectively pumped into a microreactor with a volume of 10 mL in a microchannel reaction device at a rate of 1 mL / min and 1.15 mL / min for ring-opening reaction to obtain a first reaction solution. Methyl 14-hydroxytetradecanoate (1.47 g, 5.7 mmol) and ethyl acetate (20 mL) were mixed to obtain a third mixed solution. The temperature of the reactor was adjusted to 100 °C, and the third mixed solution was pumped into the microreactor with a volume of 15 mL in the microchannel reaction device at a rate of 2 mL / min together with the first reaction solution for ring-opening reaction. The obtained reaction solution was successively washed with sodium bicarbonate solution (30 mL, 10%) and water (30 mL × 2). The organic phase was dried and concentrated to obtain soybean oil polyol with a hydroxyl value of 207 mg KOH / g, an epoxy value of 0.5, and a viscosity of 812 mPa·s.

[0078] (2) Preparation of vegetable oil-based polyurethane coating: The polyurethane coating was prepared according to the general method in (2) of Example 1.

[0079] Example 14

[0080] (1) Preparation of vegetable oil polyol: Epoxidized rapeseed oil (13.5 mL, epoxy value 4.9%, epoxy groups 38.4 mmol) and boric acid fluoride (20 mg, 50%) were mixed to obtain a first mixed solution. Dimethyl 2,3-dihydroxysuccinate (5.13 g, 28.8 mmol) and ethyl acetate (10 mL) were mixed to obtain a second mixed solution. The reactor temperature was adjusted to 100 °C, and the first and second mixed solutions were respectively pumped into a 10 mL microreactor of a microchannel reaction device at rates of 1.35 mL / min and 1.15 mL / min for ring-opening reaction to obtain a first reaction solution. Methyl 14-hydroxytetradecanoate (1.47, 5.7 mmol) and ethyl acetate (20 mL) were mixed to obtain a third mixed solution. The reactor temperature was adjusted to 100 °C, and the third mixed solution was pumped into a 15 mL microreactor of the microchannel reaction device at a rate of 2 mL / min together with the first reaction solution for ring-opening reaction. The resulting reaction solution was washed successively with sodium bicarbonate solution (30 mL, 10%) and water (30 mL × 2). The organic phase was dried and concentrated to obtain soybean oil polyol with a hydroxyl value of 182 mg KOH / g, an epoxy value of 0.5, and a viscosity of 991 mPa·s.

[0081] (2) Preparation of vegetable oil-based polyurethane coating: The polyurethane coating was prepared according to the general method in (2) of Example 1.

[0082] Example 15

[0083] (1) Preparation of vegetable oil polyol: Epoxidized corn oil (12.3 mL, epoxy value 5.2%, epoxy groups 38.4 mmol) and boric acid fluoride (20 mg, 50%) were mixed to obtain a first mixed solution. Dimethyl 2,3-dihydroxysuccinate (5.13 g, 28.8 mmol) and ethyl acetate (10 mL) were mixed to obtain a second mixed solution. The reactor temperature was adjusted to 100 °C, and the first and second mixed solutions were respectively pumped into a 10 mL microreactor of a microchannel reaction device at rates of 1.23 mL / min and 1.15 mL / min for ring-opening reaction to obtain a first reaction solution. Methyl 14-hydroxytetradecanoate (1.47 g, 5.7 mmol) and ethyl acetate (20 mL) were mixed to obtain a third mixed solution. The reactor temperature was adjusted to 100 °C, and the third mixed solution was pumped into a 15 mL microreactor of the microchannel reaction device at a rate of 2 mL / min together with the first reaction solution for ring-opening reaction. The resulting reaction solution was washed successively with sodium bicarbonate solution (30 mL, 10%) and water (30 mL × 2). The organic phase was dried and concentrated to obtain soybean oil polyol with a hydroxyl value of 188 mg KOH / g, an epoxy value of 0.5, and a viscosity of 792 mPa·s.

[0084] (2) Preparation of vegetable oil-based polyurethane coating: Prepare the polyurethane coating according to the general method in (2) of Example 1.

[0085] Example 16

[0086] (1) Preparation of vegetable oil polyol: Mix epoxidized peanut oil (14.4 mL, epoxy value 4.5%, epoxy group 38.4 mmol) and boric acid fluoride (20 mg, 50%) to obtain the first mixed solution, and mix dimethyl 2,3-dihydroxysuccinate (5.13 g, 28.8 mmol) and ethyl acetate (10 mL) to obtain the second mixed solution. Adjust the reactor temperature to 100 °C, and pump the first mixed solution and the second mixed solution into a 10 mL microreactor of a microchannel reaction device at rates of 1.44 mL / min and 1.15 mL / min respectively for ring-opening reaction to obtain the first reaction solution; Mix methyl 14-hydroxytetradecanoate (1.47 g, 5.7 mmol) and ethyl acetate (20 mL) to obtain the third mixed solution. Adjust the reactor temperature to 100 °C, and pump the third mixed solution into a 15 mL microreactor of the microchannel reaction device at a rate of 2 mL / min together with the first reaction solution for ring-opening reaction. The obtained reaction solution is washed successively with sodium bicarbonate solution (30 mL, 10%) and water (30 mL × 2). The organic phase is dried and concentrated to obtain soybean oil polyol with a hydroxyl value of 168 mg KOH / g, an epoxy value of 0.6, and a viscosity of 655 mPa·s.

[0087] (2) Preparation of vegetable oil-based polyurethane coating: Prepare the polyurethane coating according to the general method in (2) of Example 1.

[0088] Comparative Example 1

[0089] (1) Preparation of vegetable oil polyol: React epoxidized soybean oil (10 mL, epoxy value 6.2%, epoxy group 38.4 mmol), boric acid fluoride (20 mg, 50%), dimethyl 2,3-dihydroxysuccinate (5.13 g, 28.8 mmol) and ethyl acetate (30 mL) at 100 °C for 6 h, add methyl 14-hydroxytetradecanoate (1.47 g, 5.7 mmol) and continue to react for 4 h, and cool to room temperature. The obtained reaction solution is washed successively with sodium bicarbonate solution (30 mL, 10%) and water (30 mL × 2). The organic phase is dried and concentrated to obtain soybean oil polyol with a hydroxyl value of 121 mg KOH / g, an epoxy value of 1.3, and a viscosity of 1650 mPa·s.

[0090] (2) Preparation of vegetable oil-based polyurethane coating: Prepare the polyurethane coating according to the general method in (2) of Example 1.

[0091] Comparative Example 2

[0092] (1) Preparation of vegetable oil polyol: Epoxidized soybean oil (10 mL, epoxy value 6.2%, epoxy groups 38.4 mmol) and boric acid fluoride (20 mg, 50%) were mixed to obtain a first mixed solution, dimethyl 2,3-dihydroxysuccinate (4.10 g, 23.0 mmol) and ethyl acetate (10 mL) were mixed to obtain a second mixed solution. The temperature of the reactor was adjusted to 100 °C, and the first mixed solution and the second mixed solution were respectively pumped into a microreactor with a volume of 10 mL in a microchannel reaction device at a rate of 1 mL / min and 1.14 mL / min for ring-opening reaction to obtain a first reaction solution; Methyl 14-hydroxytetradecanoate (1.47 g, 5.7 mmol) and ethyl acetate (20 mL) were mixed to obtain a third mixed solution. The temperature of the reactor was adjusted to 100 °C, and the third mixed solution was pumped into a microreactor with a volume of 15 mL in the microchannel reaction device at a rate of 2 mL / min together with the first reaction solution for ring-opening reaction. The obtained reaction solution was washed successively with sodium bicarbonate solution (30 mL, 10%) and water (30 mL × 2). The organic phase was dried and concentrated to obtain soybean oil polyol with a hydroxyl value of 152 mg KOH / g, an epoxy value of 1.6, and a viscosity of 512 mPa·s.

[0093] (2) Preparation of vegetable oil-based polyurethane coating: The polyurethane coating was prepared according to the general method in (2) of Example 1.

[0094] Comparative Example 3

[0095] (1) Preparation of vegetable oil polyol: Epoxidized soybean oil (10 mL, epoxy value 6.2%, epoxy groups 38.4 mmol) and boric acid fluoride (20 mg, 50%) were mixed to obtain a first mixed solution, dimethyl 2,3-dihydroxysuccinate (6.15 g, 34.6 mmol) and ethyl acetate (10 mL) were mixed to obtain a second mixed solution. The temperature of the reactor was adjusted to 100 °C, and the first mixed solution and the second mixed solution were respectively pumped into a microreactor with a volume of 10 mL in a microchannel reaction device at a rate of 1 mL / min and 1.17 mL / min for ring-opening reaction to obtain a first reaction solution; Methyl 14-hydroxytetradecanoate (0.99 g, 4.0 mmol) and ethyl acetate (20 mL) were mixed to obtain a third mixed solution. The temperature of the reactor was adjusted to 100 °C, and the third mixed solution was pumped into a microreactor with a volume of 15 mL in the microchannel reaction device at a rate of 2 mL / min together with the first reaction solution for ring-opening reaction. The obtained reaction solution was washed successively with sodium bicarbonate solution (30 mL, 10%) and water (30 mL × 2). The organic phase was dried and concentrated to obtain soybean oil polyol with a hydroxyl value of 160 mg KOH / g, an epoxy value of 1.2, and a viscosity of 1856 mPa·s.

[0096] (2) Preparation of vegetable oil-based polyurethane coating: The polyurethane coating was prepared according to the general method in (2) of Example 1.

[0097] Comparative Example 4

[0098] (1) Preparation of vegetable oil polyol: Epoxidized soybean oil (10 mL, epoxy value 6.2%, epoxy group 38.4 mmol) and boric acid fluoride (20 mg, 50%) were mixed to obtain a first mixed solution, and dimethyl 2,3-dihydroxysuccinate (5.13 g, 28.8 mmol) and ethyl acetate (10 mL) were mixed to obtain a second mixed solution. The temperature of the reactor was adjusted to 100 °C, and the first mixed solution and the second mixed solution were pumped into a microreactor with a volume of 10 mL in a microchannel reaction device at a rate of 1 mL / min and 1.15 mL / min respectively for ring-opening reaction to obtain a first reaction solution; Methyl 14-hydroxytetradecanoate (3 g, 11.6 mmol) and ethyl acetate (20 mL) were mixed to obtain a third mixed solution. The temperature of the reactor was adjusted to 100 °C, and the third mixed solution was pumped into a microreactor with a volume of 15 mL in the microchannel reaction device at a rate of 2 mL / min together with the first reaction solution for ring-opening reaction. The resulting reaction solution was washed successively with sodium bicarbonate solution (30 mL, 10%) and water (30 mL × 2). The organic phase was dried and concentrated to obtain soybean oil polyol with a hydroxyl value of 158 mg KOH / g, an epoxy value of 1.1, and a viscosity of 1711 mPa·s.

[0099] (2) Preparation of vegetable oil-based polyurethane coating: The polyurethane coating was prepared according to the general method in (2) of Example 1.

[0100] The performance indexes of the polyurethane coatings prepared in Examples 1 - 16 and Comparative Examples 1 - 4 are shown in Table 1.

[0101] Table 1 Performance indexes of the vegetable oil-based polyurethane coatings prepared in Examples and Comparative Examples

[0102]

[0103] Table 1 (continued) Performance indexes of the vegetable oil-based polyurethane coatings prepared in Examples and Comparative Examples

[0104]

[0105] It can be seen from the data in Table 1 that in a conventional reaction flask, due to uncontrollable processes and many cross-linking side reactions, the hydroxyl value decays severely, the viscosity is high, and the performance of the vegetable oil-based polyurethane coating deteriorates. The present invention adopts microreaction technology to control the dosage of ring-opening reagents, leaving a little epoxy value, introducing poly-ester groups into the prepared vegetable oil polyol, having a relatively high hydroxyl value, and increasing the mechanical properties and toughness of the polyurethane material, with good corrosion resistance.

[0106] The present invention provides an idea and method for the preparation method of vegetable oil polyol and its application in polyurethane anticorrosive coatings. There are many methods and ways to specifically implement this technical solution. The above description is only the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention. Each component not clearly defined in this embodiment can be realized by using the prior art.

Claims

1. A method for preparing a vegetable oil polyol, characterized in that, Mix epoxy vegetable oil and an acidic catalyst to obtain a first mixed solution; dissolve a 2,3-dihydroxysuccinic acid diester compound in an organic solvent to obtain a second mixed solution; pump the first mixed solution and the second mixed solution simultaneously into a first microreactor of a microchannel reaction device to carry out a first ring-opening reaction to obtain a first reaction solution; pump a third mixed solution obtained by dissolving a long-chain hydroxy fatty acid ester in an organic solvent and the first reaction solution simultaneously into a second microreactor of the microchannel reaction device to continue carrying out a second ring-opening reaction, and collect the obtained reaction solution to obtain the product; The epoxy vegetable oil is any one or a combination of several of epoxy olive oil, epoxy peanut oil, epoxy rapeseed oil, epoxy cottonseed oil, epoxy soybean oil, epoxy coconut oil, epoxy palm oil, epoxy sesame oil, epoxy corn oil, and epoxy sunflower oil; the acidic catalyst is any one or a combination of several of fluoboric acid, concentrated sulfuric acid, p-toluenesulfonic acid, methanesulfonic acid, and benzenesulfonic acid; the 2,3-dihydroxysuccinic acid diester compound is dimethyl 2,3-dihydroxysuccinate or diisobutyl 2,3-dihydroxysuccinate; the organic solvent is any one or a combination of several of ethyl acetate, dichloromethane, dichloroethane, chloroform, n-hexane, tetrahydrofuran, 1,4-dioxane, carbon tetrachloride, toluene, and xylene; the long-chain hydroxy fatty acid ester is any one or a combination of several of methyl 14-hydroxytetradecanoate and / or ethyl 14-hydroxytetradecanoate; The mass percentage of the acidic catalyst to the epoxy vegetable oil is 0.02-0.1%:1; The mass-volume ratio of the 2,3-dihydroxysuccinic acid diester compound to the organic solvent is 1:0.5-2; The mass-volume ratio of the long-chain hydroxy fatty acid ester to the organic solvent is 1:1-4; The reaction molar ratio of the epoxy group in the epoxy vegetable oil to the 2,3-dihydroxysuccinic acid diester compound is 1:0.7-0.8; The reaction molar ratio of the epoxy group in the epoxy vegetable oil to the long-chain hydroxy fatty acid ester is 1:0.1-0.2; The volumes of both the first microreactor and the second microreactor are 5 mL to 20 mL; the reaction temperature of the first ring-opening reaction is 80-110°C, and the reaction time is 3-15 min; the reaction temperature of the second ring-opening reaction is 80-110°C, and the reaction time is 3-15 min.

2. The vegetable oil polyol prepared by any one of the preparation methods in claim 1.

3. The application of the vegetable oil polyol according to claim 2 in the preparation of polyurethane coatings.

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