Low-VOC (volatile organic compound) high-flash-point bio-based alkyd enamel and preparation method thereof

Abstract

The invention relates to the technical field of enamel paint preparation. The low-VOC high-flash-point bio-based alkyd enamel is prepared from bio-based high-flash-point alkyd resin, a graphene modified emulsifier, a modified rheological agent, a pigment, a leveling agent, a dispersant, a drier, deionized water, a solvent, potassium hydroxide and dimethyl diethanolamine. Wherein the bio-based high-flash-point alkyd resin is prepared from vegetable oil, glycerol, lithium hydroxide, vegetable oleic acid, pentaerythritol, phthalic anhydride, tetrahydrophthalic anhydride, a catalyst, itaconic acid and propylene glycol butyl ether; the graphene modified emulsifier is prepared from an alkyd resin reactive emulsifier A and amino graphene oxide dispersion liquid; the modified rheological agent is prepared from rosin powder, tetrahydrofuran, p-toluene sulfonic acid and SQ-NFC3L2 nano cellulose with the solid content of 2.5%. The flash point of the alkyd enamel prepared by the invention is more than 61 DEG C, the VOC is less than 350g / L, the heat storage stability is more than 30d, the skinning property is more than 48h without skinning, the gloss of a paint film (60 DEG C) is more than or equal to 80, the surface drying time is less than 1h, and the hard drying time is less than 12h.

Description

Technical Field

[0001] The present invention relates to the technical field of coating preparation, and particularly relates to a bio-based alkyd coating that can be used in the field of enamel paint. Background Art

[0002] Bio-based materials can reduce greenhouse gas emissions during production and use, contributing to the goal of "carbon peak". Existing alkyd coatings are coatings developed by combining bio-based materials and petrochemical raw materials, and they have developed rapidly in the coating field and account for a relatively large proportion. Currently, in order to meet the requirements for the identification of non-hazardous chemicals in the "Regulations on the Safety Management of Hazardous Chemicals", some research has been carried out on high flash point alkyd coating products. For example, patent (CN 118271940A) discloses an alkyd exterior enamel paint and its preparation method. Using a bio-based high flash point alkyd resin as the matrix resin, a bio-based exterior enamel paint with high flash point, high adhesion, high aging resistance and high wear resistance is prepared. However, a large amount of high-boiling solvents are used, resulting in too high VOC content in the alkyd enamel paint, and the film drying is slow. Patent (CN 106750213B) discloses a method for preparing bio-based alkyd resin from fatty acid methyl ester. Using bio-based fatty acid methyl ester as the main raw material to prepare alkyd resin, with 200# gasoline as the main solvent, the flash point of this product is <60°C, which does not meet the requirements for the identification of non-hazardous chemicals in the "Regulations on the Safety Management of Hazardous Chemicals".

[0003] Currently, the alkyd enamel paints on the market still have problems such as slow film drying, low flash point of the coating, high VOC content, and relatively low bio-based proportion. Summary of the Invention

[0004] The purpose of the present invention is to use bio-based materials to replace part of the petrochemical raw materials, reduce carbon emissions, and provide a bio-based alkyd enamel paint with high bio-based content, high flash point, low VOC, fast film drying, and excellent physical and chemical properties, aiming at the problems of slow film drying, low flash point of the coating, high VOC content, etc. of existing products.

[0005] A low-VOC high-flash-point bio-based alkyd enamel paint is prepared from the following components by weight:

[0006]

[0007] The sum of the weights of the above components is 100 parts;

[0008] The bio-based high-flash-point alkyd resin is prepared from the following components by weight:

[0009]

[0010]

[0011] The sum of the weight parts of the above components is 100 parts;

[0012] Preferably, the vegetable oil is one or both of perilla oil and prickly ash oil with an iodine value (gI2 / 100g) between 125 and 140;

[0013] Preferably, the vegetable oil acid is one or both of tung oil acid and linolenic acid with an iodine value (gI2 / 100g) between 140 and 200;

[0014] Preferably, the catalyst is one or several of stannous oxide, stannous octoate, and monobutyltin oxide;

[0015] The graphene-modified emulsifier is prepared from the following components by weight:

[0016] Alkyd resin reactive emulsifier A 60 - 75 parts

[0017] Amino graphene oxide dispersion 25 - 40 parts

[0018] The sum of the weight parts of the above components is 100 parts;

[0019] Among them, the alkyd resin reactive emulsifier A is prepared from the following components by weight:

[0020]

[0021] The sum of the weight parts of the above components is 100 parts;

[0022] Preferably, the polyethylene glycol is one of polyethylene glycol 4000 and polyethylene glycol 6000;

[0023] Preferably, the polyethylene glycol diglycidyl ether is selected from one with a molecular weight of 500 - 1000;

[0024] Preferably, the amino graphene oxide dispersion is polyethylene glycol - amino modified graphene oxide;

[0025] The modified rheological agent is prepared from the following components by weight:

[0026]

[0027] Preferably, the pigment is one or two of titanium dioxide, carbon black, iron oxide red, and iron oxide yellow.

[0028] Preferably, the leveling agent is one of BYK - 310, BYK - 306, and EFKA - 3033.

[0029] Preferably, the dispersant is a bio-based dispersant, such as one or two of dispersant NNO, dispersant M-9, and dispersant MF.

[0030] Preferably, the drier is one or two of SDJ9903, SDJ T-12, SDJ 9902, and SDJ T-20.

[0031] Preferably, the solvent is a solvent with a flash point > 61°C, such as one of SA-1000, SA-1500, SA-1800, and SA-2000.

[0032] Another object of the present invention is to provide a method for preparing the above low-VOC high-flash-point bio-based alkyd enamel, which specifically includes the following steps:

[0033] Step 1: Prepare a bio-based high-flash-point alkyd resin

[0034] Add (10 - 30) parts of vegetable oil and (5 - 10) parts of glycerol into a reactor equipped with a stirring device, a reflux condenser, a temperature control device, and a vacuum pumping device. Heat up to 120°C and add (0.1 - 1) part of lithium hydroxide. After heating up to 250°C and reacting for (1 - 3) h, cool down to below 80°C. Then add (20 - 35) parts of vegetable oil acid, (5 - 10) parts of pentaerythritol, (10 - 15) parts of phthalic anhydride, (5 - 10) parts of tetrahydrophthalic anhydride, and (0.05 - 1) part of catalyst. Heat up to 150°C ± 5°C, keep warm for 1 h, then heat up to 180°C ± 5°C and keep warm for 1 h, and then heat up to 210°C ± 5°C and keep warm for 1 h. Cool down to below 180°C and add xylene, then heat up to 220°C ± 5°C and reflux until the acid value is below 15 mgKOH / g. Cool down and add (0.5 - 1.5) part of itaconic acid, and continue to reflux at 220°C ± 5°C until the acid value drops to below 10 mgKOH / g. After vacuum pumping, add (10 - 20) parts of propylene glycol monobutyl ether and stir evenly to obtain it;

[0035] Step 2: Prepare a graphene-modified emulsifier

[0036] (45 - 55) parts of polyethylene glycol, (10 - 20) parts of tung oil acid, (1 - 10) parts of glycerol, (10 - 20) parts of phthalic anhydride, and (5 - 10) parts of benzoic acid were added to a reactor equipped with a stirring device, a reflux condenser, a temperature control device, and a vacuum pumping device. The temperature was raised to 150°C ± 5°C, and after holding for 1 h, the temperature was further raised to 180°C ± 5°C and held for 1 h, and then raised to 210°C ± 5°C until clear. Xylene was added and the temperature was raised to 220°C ± 5°C and refluxed until the acid value reached 20 mg KOH / g; the temperature was lowered to 180°C ± 5°C, (3 - 5) parts of polyethylene glycol diglycidyl ether were added, and after holding until the acid value remained unchanged, xylene was removed by vacuum pumping. The temperature was lowered and (5 - 15) parts of propylene glycol butyl ether were added for dilution and dispersion to obtain the alkyd resin reactive emulsifier A; (60 - 75) parts of the alkyd resin reactive emulsifier A and (25 - 40) parts of the amino-functionalized graphene dispersion were added to a reaction kettle, and the temperature was raised to 50°C - 60°C and stirred at high speed for (1 - 2) h to obtain;

[0037] Step 3: Preparation of the modified rheology modifier

[0038] 50 parts of rosin powder, 38 parts of tetrahydrofuran, 2 parts of the catalyst p-toluenesulfonic acid, and 10 parts of SQ-NFC3L2 nanocellulose with a solid content of 2.5% were added to a reactor equipped with a stirring device, a reflux condenser, a temperature control device, and a vacuum pumping device. The temperature was raised to 155°C ± 5°C and held for 15 h for reaction, and then the temperature was lowered for standby;

[0039] Step 4: Preparation of the low-VOC high-flash-point bio-based alkyd enamel

[0040] (50 - 70) parts of the bio-based high-flash-point alkyd resin, (0.1 - 0.5) parts of potassium hydroxide, and (0.1 - 0.5) parts of dimethyldiethanolamine were put into a high-speed mixer with a rotation speed of (1000 - 1500) r / min. The temperature was raised to 60°C - 70°C, and (5 - 15) parts of the graphene-modified emulsifier were added. After holding for dispersion for 20 min, (10 - 20) parts of deionized water were slowly added within 30 min until inversion occurred, and then the rotation speed was adjusted to (1500 - 2000) r / min for high-speed dispersion for 30 min, and then cooled to room temperature. (2 - 5) parts of the dispersant, (10 - 20) parts of the pigment, (0.1 - 0.5) parts of the leveling agent, (0.5 - 2) parts of the drier, and (1 - 5) parts of the modified rheology modifier were added in sequence. After dispersion and grinding, (2 - 6) parts of the solvent were added to adjust the viscosity, and after filtration, a low-VOC high-flash-point bio-based alkyd enamel with a viscosity of 80 ± 10 s (ISO No. 6 cup, 23°C), a solid content of 65% ± 5%, a flash point > 61°C, and a VOC ≤ 350 g / L was obtained.

[0041] The present invention improves the bio - based content of alkyd enamel by increasing the oil or oleic acid in alkyd resin. Using excessive tung oil acid and linolenic acid in alkyd resin will cause a decrease in film hardness, weather resistance, easy yellowing and easy cracking. Mixing perilla oil and prickly ash oil can adjust the film drying speed, and improve the film hardness, toughness, weather resistance, gloss and fullness. Further mixing itaconic acid, tetrahydrophthalic anhydride, glycerol and pentaerythritol can increase the resin branching degree and cross - link point density, improve the film drying speed, and enhance the film hardness, adhesion, gloss and weather resistance performance; tetrahydrophthalic anhydride can increase the compatibility between the resin and the solvent, reduce the viscosity of alkyd resin and reduce the solvent consumption.

[0042] The present invention uses polyethylene glycol and polyethylene glycol diglycidyl ether to step - by - step modify low - molecular - weight alkyd resin to prepare a reactive emulsifier with epoxy groups and graft it with amino - functionalized graphene oxide to prepare an amino - functionalized graphene oxide modified emulsifier. Graphene and the emulsifier are tightly connected by chemical bonds, solving the problems of difficult dispersion and easy agglomeration of graphene. At the same time, a dense isolation layer is formed in the paint film, effectively improving the anti - corrosion property, strength, weather resistance and water resistance of the paint film; the graphene modified emulsifier modified in this way has a good emulsifying effect on alkyd resin, which helps to improve the storage stability of the coating and reduce the VOC of the coating.

[0043] The present invention uses rosin - modified nanocellulose to prepare an amphiphilic rheological agent with both hydrophilic and lipophilic properties. It not only improves the compatibility between nanocellulose and alkyd resin during paint making, but also increases the compatibility between alkyd resin and water, improves the storage stability of the coating, and retains the characteristics of nanocellulose such as nanomaterials, three - dimensional shape, obvious fibrils, large specific surface area and shear thinning; nanocellulose forms drainage channels in the paint film, which has a synergistic effect on the film drying, and enhances the strength, hardness, wear resistance, impact resistance and denseness of the coating. This structure can effectively prevent problems such as cracking and peeling of the coating.

[0044] When making paint, the present invention introduces lignosulfonate as a bio - based dispersant, which can increase the bio - based content of the coating, can quickly disperse pigments in water, and improve the grinding efficiency of paint making; this dispersant is connected by phenylpropane and ether bonds, and has the effects of emulsification, defoaming and stabilizing the emulsion; it can reduce the use of emulsifier and defoamer and increase the stability.

[0045] The beneficial effects of the present invention:

[0046] I. The present invention uses polyols, polyacids, and vegetable fatty acids as synthesis raw materials. By adjusting the ratio of vegetable oil and vegetable fatty acid, the drying speed, hardness, toughness, gloss, fullness, and weather resistance of the paint film are adjusted; by adjusting the ratio of polyols and polyacids, the degree of branching and crosslinking point density of the resin are adjusted, the drying speed of the paint film is increased, and the hardness and adhesion of the coating are improved. Bio-based itaconic acid is a dicarboxylic acid containing unsaturated double bonds obtained by microbial fermentation, which increases the bio-based content. At the same time, tetrahydrophthalic anhydride is used to reduce the resin viscosity and introduce polar groups to assist resin emulsification, and the amount of water is increased to further reduce VOC. The prepared paint has VOC < 350 g / L, surface dryness of the paint film < 1 h, through drying < 12 h, bending test / mm ≤ 3, and hardness (double pendulum) ≥ 0.2.

[0047] II. The present invention synthesizes a reactive emulsifier with epoxy groups using polyethylene glycol, polyethylene glycol diglycidyl ether, and low molecular weight alkyd resin, and performs an addition reaction with amino graphene oxide. Graphene and the emulsifier are tightly connected by chemical bonds, solving the problems of difficult dispersion and easy agglomeration of graphene. At the same time, a dense isolation layer is formed in the paint film, making the paint film resistant to salt spray for 300 h without abnormality; the graphene-modified emulsifier has good emulsification effect and can improve the storage stability of the paint. The paint material is stored at 50 °C ± 5 °C for 30 d without abnormality.

[0048] III. The present invention uses a modified rheology agent. The amphiphilic rheology agent prepared by rosin modification improves the compatibility of nanocellulose and alkyd resin. The polar groups in the resin and the hydroxyl groups of nanocellulose are conducive to hydrogen bonding, forming a firm three-dimensional interpenetrating network system. After film formation, the density and gloss of the paint film are improved, and the water resistance, strength, hardness, and rigidity of the paint film are increased; nanocellulose has good rheological properties, improving the rheological properties of the paint and realizing shear thinning; nanocellulose presents a three-dimensional shape in the paint film, with characteristics such as large specific surface area and obvious fibrils, enabling it to be widely dispersed within the paint system and forming many stable drainage channels, improving the drying rate of the coating.

[0049] IV. The present invention uses lignosulfonate as a dispersant, which is easily soluble in water, has certain surface activity and stable emulsification effect. It is beneficial to disperse pigments evenly in water and resin, reduce the usage amount of solvents, improve the effective utilization rate of powder materials, and improve the paint-making efficiency.

[0050] V. The alkyd enamel prepared by the present invention has a flash point > 61 °C; VOC < 350 g / L; thermal storage stability > 30 d; skinning resistance > 48 h without skinning; paint film gloss (60°) ≥ 80; surface dryness < 1 h, through drying < 12 h; bending test / mm ≤ 3; hardness (double pendulum) ≥ 0.2; water resistance > 10 h, resistance to volatile oil > 6 h, salt spray resistance > 200 h, resistance to artificial weathering > 300 h, all without abnormality. Detailed implementation mode

[0051] Example 1

[0052] Step 1: Prepare bio-based high flash point alkyd resin

[0053] Add 10 parts of perilla oil, 12 parts of prickly ash oil and 8 parts of glycerol into a reactor equipped with a stirring device, a reflux condenser, a temperature control device and a vacuum pumping device. Heat up to 120 °C and add 0.2 part of lithium hydroxide. Then heat up to 250 °C and react for 1 h. After the alcoholysis is completed, cool down to 80 °C and add 19 parts of tung oil acid, 10 parts of linolenic acid, 5.9 parts of pentaerythritol, 13 parts of phthalic anhydride, 7.8 parts of tetrahydrophthalic anhydride and 0.1 part of catalyst. Heat up to 150 °C ± 5 °C, keep warm for 1 h, then heat up to 180 °C ± 5 °C and keep warm for 1 h, and then rise to 210 °C ± 5 °C and keep warm until clear. Add xylene and heat up to 220 °C ± 5 °C and reflux until the acid value is below 15 mg KOH / g. Cool down and add 1 part of itaconic acid, and then continue to heat up at 220 °C ± 5 °C and reflux react until the acid value drops below 10 mg KOH / g. After vacuum pumping, add 13 parts of propylene glycol butyl ether and stir evenly. After cooling to room temperature, it is reserved for use.

[0054] Step 2: Prepare graphene-modified emulsifier

[0055] Add 45 parts of polyethylene glycol, 12 parts of vegetable oleic acid, 8 parts of glycerol, 18 parts of phthalic anhydride and 5 parts of benzoic acid into a reactor equipped with a stirring device, a reflux condenser, a temperature control device and a vacuum pumping device. Heat up to 150 °C ± 5 °C, keep warm for 1 h, then heat up to 180 °C ± 5 °C and keep warm for 1 h, and then rise to 210 °C ± 5 °C and keep warm until clear. Add xylene and heat up to 220 °C ± 5 °C and reflux until the acid value is 20 mg KOH / g. Cool down to 180 °C ± 5 °C and add 4 parts of polyethylene glycol diglycidyl ether. Keep warm until the acid value remains unchanged, then vacuum pump to remove xylene. Cool down and add 8 parts of propylene glycol butyl ether for dilution and dispersion to obtain alkyd resin reactive emulsifier A. Add 65 parts of alkyd resin reactive emulsifier A and 35 parts of amino graphene oxide dispersion into a reaction kettle, heat up to 50 °C - 60 °C and stir at high speed for 1 h - 2 h to obtain a graphene-modified emulsifier with graphene uniformly dispersed.

[0056] Step 3: Prepare modified rheology modifier

[0057] Put 50 parts of rosin powder, 38 parts of tetrahydrofuran, 2 parts of catalyst p-toluenesulfonic acid and 10 parts of SQ-NFC3L2 nanocellulose with a solid content of 2.5% into a reactor equipped with a stirring device, a reflux condenser, a temperature control device and a vacuum pumping device. Heat up to 155 °C ± 5 °C and keep warm and react for 15 h, then cool down and reserve for use.

[0058] Step 4: Prepare high flash point bio-based alkyd enamel

[0059] Add 57.4 parts of bio-based high flash point alkyd resin, 0.2 parts of potassium hydroxide and 0.3 parts of dimethyldiethanolamine into a high-speed mixer. The rotation speed is (1000 - 1500) r / min. Heat up to 60°C - 70°C and add 15 parts of graphene-modified emulsifier. After heat preservation and dispersion for 20 min, slowly add 10 parts of deionized water within 30 min until inversion occurs. Then adjust the rotation speed to (1500 - 2000) r / min and disperse at high speed for 30 min, and then cool down to room temperature. Add 1 part of dispersant, 12 parts of pigment, 0.1 part of leveling agent, 0.5 part of dryer and 1.5 parts of modified rheology agent in sequence. After dispersion and grinding, add 2 parts of solvent to adjust the viscosity, and filter to obtain high flash point bio-based alkyd enamel.

[0060] Example 2:

[0061] Step 1: Prepare bio-based high flash point alkyd resin

[0062] Add 5 parts of perilla oil, 17 parts of prickly ash oil and 8 parts of glycerol into a reactor equipped with a stirring device, a reflux condenser, a temperature control device and a vacuum pumping device. Heat up to 120°C and add 0.2 parts of lithium hydroxide. Heat up to 250°C and react for 1 h. After alcoholysis is completed, cool down to 80°C and add 19 parts of tung oil acid, 10 parts of linolenic acid, 5.9 parts of pentaerythritol, 13 parts of phthalic anhydride, 7.8 parts of tetrahydrophthalic anhydride and 0.1 part of catalyst. Heat up to 150°C ± 5°C, keep warm for 1 h, then heat up to 180°C ± 5°C and keep warm for 1 h, and then rise to 210°C ± 5°C and keep warm until clear. Add xylene and heat up to 220°C ± 5°C and reflux until the acid value is below 15 mg KOH / g. Cool down and add 1 part of itaconic acid, and continue to reflux at 220°C ± 5°C until the acid value drops below 10 mg KOH / g. After vacuum pumping, add 13 parts of propylene glycol butyl ether and stir evenly. Keep it at room temperature for later use.

[0063] Step 2: Prepare graphene-modified emulsifier

[0064] Add 45 parts of polyethylene glycol, 12 parts of vegetable oleic acid, 8 parts of glycerol, 18 parts of phthalic anhydride and 5 parts of benzoic acid into a reactor equipped with a stirring device, a reflux condenser, a temperature control device and a vacuum pumping device. Heat up to 150°C ± 5°C, keep warm for 1 h, then heat up to 180°C ± 5°C and keep warm for 1 h, and then rise to 210°C ± 5°C and keep warm until clear. Add xylene and heat up to 220°C ± 5°C and reflux until the acid value is 20 mg KOH / g. Cool down to 180°C ± 5°C and add 4 parts of polyethylene glycol diglycidyl ether. Keep warm until the acid value remains unchanged, then vacuum pump to remove xylene. Cool down and add 8 parts of propylene glycol butyl ether for dilution and dispersion to obtain alkyd resin reactive emulsifier A. Add 65 parts of alkyd resin reactive emulsifier A and 35 parts of amino graphene dispersion liquid into the reaction kettle, heat up to 50°C - 60°C and stir at high speed for 1 h - 2 h to obtain graphene-modified emulsifier with graphene evenly dispersed.

[0065] Step 3: Prepare modified rheological agent

[0066] Put 50 parts of rosin powder, 38 parts of tetrahydrofuran, 2 parts of catalyst p-toluenesulfonic acid, and 10 parts of SQ-NFC3L2 nanocellulose with a solid content of 2.5% into a reactor equipped with a stirring device, a reflux condenser, a temperature control device, and a vacuum pumping device. Heat up to 155°C ± 5°C, keep the temperature for reaction for 15 hours, and then cool down for standby.

[0067] Step 4: Prepare high flash point bio-based alkyd enamel

[0068] Add 59.4 parts of bio-based high flash point alkyd resin, 0.2 part of potassium hydroxide, and 0.3 part of dimethyldiethanolamine to a high-speed mixer. The rotation speed is (1000 - 1500) r / min. Heat up to 60°C - 70°C, add 10 parts of graphene modified emulsifier, keep the temperature for dispersion for 20 minutes, then slowly add 10 parts of deionized water within 30 minutes until inversion occurs, adjust the rotation speed to (1500 - 2000) r / min, disperse at high speed for 30 minutes, then cool down to room temperature. Add 1 part of dispersant, 14 parts of pigment, 0.1 part of leveling agent, 0.5 part of drier, and 2.5 parts of modified rheological agent in sequence. After dispersion and grinding, add 2 parts of solvent to adjust the viscosity, and filter to obtain high flash point bio-based alkyd enamel.

[0069] Example 3:

[0070] Step 1: Prepare bio-based high flash point alkyd resin

[0071] Add 17 parts of perilla oil, 5 parts of prickly ash oil, and 8 parts of glycerol to a reactor equipped with a stirring device, a reflux condenser, a temperature control device, and a vacuum pumping device. Heat up to 120°C, add 0.2 part of lithium hydroxide, heat up to 250°C and react for 1 hour. After alcoholysis is completed, cool down to 80°C, add 19 parts of tung oil acid, 10 parts of linolenic acid, 5.9 parts of pentaerythritol, 13 parts of phthalic anhydride, 7.8 parts of tetrahydrophthalic anhydride, and 0.1 part of catalyst. Heat up to 150°C ± 5°C, keep the temperature for 1 hour, then heat up to 180°C ± 5°C and keep the temperature for 1 hour, then rise to 210°C ± 5°C and keep the temperature until it becomes clear. Add xylene, heat up to 220°C ± 5°C and reflux until the acid value is below 15 mgKOH / g, cool down, add 1 part of itaconic acid, continue to reflux at 220°C ± 5°C until the acid value drops below 10 mgKOH / g, evacuate, add 13 parts of propylene glycol monobutyl ether, stir evenly, and cool down to room temperature for standby.

[0072] Step 2: Prepare graphene modified emulsifier

[0073] In a reactor equipped with a stirring device, a reflux condenser, a temperature control device, and a vacuum pumping device, add 45 parts of polyethylene glycol, 12 parts of vegetable oleic acid, 8 parts of glycerol, 18 parts of phthalic anhydride, and 5 parts of benzoic acid. Heat up to 150 °C ± 5 °C, keep warm for 1 h, then heat up to 180 °C ± 5 °C and keep warm for 1 h, and then rise to 210 °C ± 5 °C and keep warm until clear. Add xylene and heat up to 220 °C ± 5 °C and reflux until the acid value reaches 20 mgKOH / g. Cool down to 180 °C ± 5 °C and add 4 parts of polyethylene glycol diglycidyl ether. Keep warm until the acid value remains unchanged, then pump out the xylene under vacuum. Cool down and add 8 parts of propylene glycol monobutyl ether for dilution and dispersion to obtain the alkyd resin reactive emulsifier A. Add 65 parts of the alkyd resin reactive emulsifier A and 35 parts of the amino-functionalized graphene dispersion into the reaction kettle, heat up to 50 °C - 60 °C and stir at high speed for 1 h - 2 h to obtain the graphene-modified emulsifier with uniformly dispersed graphene.

[0074] Step 3: Prepare the modified rheological agent

[0075] Put 50 parts of rosin powder, 38 parts of tetrahydrofuran, 2 parts of the catalyst p-toluenesulfonic acid, and 10 parts of SQ-NFC3L2 nanocellulose with a solid content of 2.5% into a reactor equipped with a stirring device, a reflux condenser, a temperature control device, and a vacuum pumping device. Heat up to 155 °C ± 5 °C and keep the reaction warm for 15 h, then cool down for standby.

[0076] Step 4: Prepare the high flash point bio-based alkyd enamel

[0077] In a high-speed mixer, add 60 parts of the bio-based high flash point alkyd resin, 0.2 part of potassium hydroxide, and 0.3 part of dimethyldiethanolamine. The rotation speed is (1000 - 1500) r / min. Heat up to 60 °C - 70 °C and add 9 parts of the graphene-modified emulsifier. Keep warm and disperse for 20 min, then slowly add 10 parts of deionized water within 30 min until phase inversion occurs. Adjust the rotation speed to (1500 - 2000) r / min and disperse at high speed for 30 min, then cool down to room temperature. Add 1 part of dispersant, 13.1 parts of pigment, 0.1 part of leveling agent, 0.5 part of drier, and 3.8 parts of the modified rheological agent in sequence. After dispersion and grinding, add 2 parts of solvent to adjust the viscosity, and filter to obtain the high flash point bio-based alkyd enamel.

[0078] Comparative Example 1:

[0079] Step 1: Prepare the bio-based high flash point alkyd resin

[0080] In a reactor equipped with a stirring device, a reflux condenser, a temperature control device, and a vacuum pumping device, add 22 parts of perilla oil and 8 parts of glycerol. Heat up to 120 °C, add 0.2 part of lithium hydroxide, heat up to 250 °C and react for 1 h. After the alcoholysis is completed, cool down to 80 °C, add 29 parts of tung oil acid, 5.9 parts of pentaerythritol tetra, 13 parts of phthalic anhydride, 7.8 parts of tetrahydrophthalic anhydride, and 0.1 part of catalyst. Heat up to 150 °C ± 5 °C, keep warm for 1 h, then heat up to 180 °C ± 5 °C and keep warm for 1 h, then rise to 210 °C ± 5 °C and keep warm until clear. Add xylene, heat up to 220 °C ± 5 °C and reflux until the acid value is below 15 mg KOH / g. Cool down, add 1 part of itaconic acid, continue to heat up and reflux at 220 °C ± 5 °C until the acid value drops below 10 mg KOH / g. After vacuum pumping, add 13 parts of propylene glycol monobutyl ether and stir evenly. Keep it for use after cooling down to room temperature.

[0081] Step 2: Prepare graphene-modified emulsifier

[0082] In a reactor equipped with a stirring device, a reflux condenser, a temperature control device, and a vacuum pumping device, add 45 parts of polyethylene glycol, 12 parts of vegetable oleic acid, 8 parts of glycerol, 18 parts of phthalic anhydride, and 5 parts of benzoic acid. Heat up to 150 °C ± 5 °C, keep warm for 1 h, then heat up to 180 °C ± 5 °C and keep warm for 1 h, then rise to 210 °C ± 5 °C and keep warm until clear. Add xylene, heat up to 220 °C ± 5 °C and reflux until the acid value is 20 mg KOH / g. Cool down to 180 °C ± 5 °C, add 4 parts of polyethylene glycol diglycidyl ether, keep warm until the acid value remains unchanged, then vacuum pump to remove xylene. Cool down, add 8 parts of propylene glycol monobutyl ether for dilution and dispersion to obtain alkyd resin reactive emulsifier A. Add 65 parts of alkyd resin reactive emulsifier A and 35 parts of amino graphene dispersion liquid into the reaction kettle, heat up to 50 °C - 60 °C and stir at high speed for 1 h - 2 h to obtain a graphene-modified emulsifier with graphene evenly dispersed.

[0083] Step 3: Prepare high flash point bio-based alkyd enamel

[0084] In a high-speed mixer, add 61.5 parts of bio-based high flash point alkyd resin, 0.2 part of potassium hydroxide, and 0.3 part of dimethyldiethanolamine. The rotation speed is (1000 - 1500) r / min. Heat up to 60 °C - 70 °C, add 5 parts of graphene-modified emulsifier, keep warm and disperse for 20 min, then slowly add 16 parts of deionized water within 30 min until inversion occurs, adjust the rotation speed to (1500 - 2000) r / min and disperse at high speed for 30 min, then cool down to room temperature. Add 14 parts of pigment, 0.5 part of leveling agent, and 0.5 part of dryer in sequence. After dispersion and grinding, add 2 parts of solvent to adjust the viscosity, and filter to obtain high flash point bio-based alkyd enamel.

[0085] Comparative Example 2:

[0086] Step 1: Prepare bio-based high flash point alkyd resin

[0087] In a reactor equipped with a stirring device, a reflux condenser, a temperature control device and a vacuum pumping device, add 22 parts of prickly ash oil and 8 parts of glycerol, heat up to 120 °C, add 0.2 part of lithium hydroxide, heat up to 250 °C and react for 1 h. After the alcoholysis is completed, cool down to 80 °C, add 29 parts of tung oil acid, 5.9 parts of pentaerythritol, 13 parts of phthalic anhydride, 7.8 parts of tetrahydrophthalic anhydride and 0.1 part of catalyst, heat up to 150 °C ± 5 °C, keep warm for 1 h, then heat up to 180 °C ± 5 °C and keep warm for 1 h, then rise to 210 °C ± 5 °C and keep warm until clear, add xylene, heat up to 220 °C ± 5 °C and reflux until the acid value is below 15 mg KOH / g, cool down, add 1 part of itaconic acid, continue to heat up and reflux at 220 °C ± 5 °C until the acid value drops below 10 mg KOH / g, evacuate the air, add 13 parts of propylene glycol butyl ether, stir evenly, and keep it for use after cooling to room temperature.

[0088] Step 2: Prepare graphene-modified emulsifier

[0089] In a reactor equipped with a stirring device, a reflux condenser, a temperature control device and a vacuum pumping device, add 45 parts of polyethylene glycol, 12 parts of vegetable oleic acid, 8 parts of glycerol, 18 parts of phthalic anhydride, 5 parts of benzoic acid, heat up to 150 °C ± 5 °C, keep warm for 1 h, then heat up to 180 °C ± 5 °C and keep warm for 1 h, then rise to 210 °C ± 5 °C and keep warm until clear, add xylene, heat up to 220 °C ± 5 °C and reflux until the acid value is 20 mg KOH / g, cool down to 180 °C ± 5 °C, add 4 parts of polyethylene glycol diglycidyl ether, keep warm until the acid value remains unchanged, evacuate the xylene under vacuum, cool down, add 8 parts of propylene glycol butyl ether for dilution and dispersion to obtain alkyd resin reactive emulsifier A. Add 65 parts of alkyd resin reactive emulsifier A and 35 parts of amino graphene dispersion liquid to the reaction kettle, heat up to 50 °C - 60 °C and stir at high speed for 1 h - 2 h to obtain graphene-modified emulsifier with graphene evenly dispersed.

[0090] Step 3: Prepare high flash point bio-based alkyd enamel

[0091] In a high-speed mixer, add 60 parts of bio-based high flash point alkyd resin, 0.2 part of potassium hydroxide and 0.3 part of dimethyldiethanolamine, the rotation speed is (1000 - 1500) r / min, heat up to 60 °C - 70 °C, add 5 parts of graphene-modified emulsifier, keep warm and disperse for 20 min, then slowly add 15 parts of deionized water within 30 min until inversion occurs, adjust the rotation speed to (1500 - 2000) r / min and disperse at high speed for 30 min, then cool down to room temperature, add 3 parts of dispersant, 13.9 parts of pigment, 0.1 part of leveling agent, 0.5 part of drier in sequence, after dispersion and grinding, add 2 parts of solvent to adjust the viscosity, and filter to obtain high flash point bio-based alkyd enamel.

[0092] Comparative Example 3:

[0093] Step 1: Prepare bio-based high flash point alkyd resin

[0094] Add 10 parts of perilla oil, 12 parts of prickly ash oil and 8 parts of glycerol into a reactor equipped with a stirring device, a reflux condenser, a temperature control device and a vacuum pumping device, heat up to 120°C, add 0.2 parts of lithium hydroxide, heat up to 250°C and react for 1 h. After the alcoholysis is completed, cool down to 80°C, add 29 parts of tung oil acid, 5.9 parts of pentaerythritol, 13 parts of phthalic anhydride, 7.8 parts of tetrahydrophthalic anhydride and 0.1 part of catalyst, heat up to 150°C ± 5°C, keep warm for 1 h, then heat up to 180°C ± 5°C and keep warm for 1 h, then rise to 210°C ± 5°C and keep warm until clear. Add xylene, heat up to 220°C ± 5°C and reflux until the acid value is below 15 mgKOH / g, cool down, add 1 part of itaconic acid, continue to heat up and reflux at 220°C ± 5°C until the acid value drops below 10 mgKOH / g, evacuate the air, add 13 parts of propylene glycol monobutyl ether, stir evenly, and set aside after cooling to room temperature.

[0095] Step 2: Prepare graphene modified emulsifier

[0096] Add 45 parts of polyethylene glycol, 12 parts of vegetable oleic acid, 8 parts of glycerol, 18 parts of phthalic anhydride, 5 parts of benzoic acid into a reactor equipped with a stirring device, a reflux condenser, a temperature control device and a vacuum pumping device, heat up to 150°C ± 5°C, keep warm for 1 h, then heat up to 180°C ± 5°C and keep warm for 1 h, then rise to 210°C ± 5°C and keep warm until clear. Add xylene, heat up to 220°C ± 5°C and reflux until the acid value is 20 mgKOH / g, cool down to 180°C ± 5°C, add 4 parts of polyethylene glycol diglycidyl ether, keep warm until the acid value remains unchanged, evacuate the xylene, cool down, add 8 parts of propylene glycol monobutyl ether for dilution and dispersion to obtain alkyd resin reactive emulsifier A. Add 65 parts of alkyd resin reactive emulsifier A and 35 parts of amino graphene dispersion into the reaction kettle, heat up to 50°C - 60°C and stir at high speed for 1 h - 2 h to obtain graphene modified emulsifier with graphene evenly dispersed.

[0097] Step 3: Prepare modified rheology agent

[0098] Put 50 parts of rosin powder, 38 parts of tetrahydrofuran, 2 parts of catalyst p-toluenesulfonic acid and 10 parts of SQ-NFC3L2 nanocellulose with a solid content of 2.5% into a reactor equipped with a stirring device, a reflux condenser, a temperature control device and a vacuum pumping device, heat up to 155°C ± 5°C, keep warm and react for 15 h, then cool down and set aside.

[0099] Step 4: Prepare high flash point bio-based alkyd enamel

[0100] Add 60 parts of bio-based high flash point alkyd resin, 0.2 part of potassium hydroxide and 0.3 part of dimethyldiethanolamine into a high-speed mixer. The rotation speed is (1000 - 1500) r / min. Heat up to 60°C - 70°C and add 5 parts of graphene-modified emulsifier. After heat preservation and dispersion for 20 min, slowly add 16 parts of deionized water within 30 min until phase inversion occurs. Then adjust the rotation speed to (1500 - 2000) r / min and disperse at high speed for 30 min, and then cool down to room temperature. Sequentially add 13.4 parts of pigment, 0.1 part of leveling agent, 0.5 part of drier and 2.5 parts of modified rheology agent. After dispersion and grinding, add 2 parts of solvent to adjust the viscosity, and filter to obtain high flash point bio-based alkyd enamel paint.

[0101] Select a suitable wire bar to scrape and prepare test panels. Place them at room temperature and wait for the paint film to dry naturally before performing performance tests. The results of Examples 1 - 3 and Comparative Examples 1 - 3 are as follows.

[0102]

[0103] The above is only the preferred embodiment of the present invention, and does not impose any form of limitation on the present invention. Although the present invention has been disclosed above with the preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to the above-disclosed technical content to obtain equivalent embodiments with equivalent changes, but as long as it does not depart from the technical content of the present invention, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A low-VOC and high-flash-point bio-based alkyd enamel, characterized in that: Prepared from the following components by weight parts: The sum of the weight parts of the above components is 100 parts; The bio-based high flash point alkyd resin is prepared from the following components by weight parts: The sum of the weight parts of the above components is 100 parts; The graphene modified emulsifier is prepared from the following components by weight parts: Alkyd resin reactive emulsifier A 60 - 75 parts Amino graphene oxide dispersion 25 - 40 parts The sum of the weight parts of the above components is 100 parts; Among them, the alkyd resin reactive emulsifier A is prepared from the following components by weight parts: The sum of the weight parts of the above components is 100 parts; The modified rheology modifier is prepared from the following components by weight parts: Rosin powder 50 parts Tetrahydrofuran 38 parts p-Toluenesulfonic acid 2 parts SQ-NFC3L2 nanocellulose with a solid content of 2.5% 10 parts.

2. The preparation method of the low-VOC and high-flash-point bio-based alkyd enamel according to claim 1, characterized in that: Including the following steps: Step 1: Prepare the bio-based high flash point alkyd resin Add (10 - 30) parts of vegetable oil and (5 - 10) parts of glycerol into a reactor equipped with a stirring device, a reflux condenser, a temperature control device and a vacuum pumping device. Heat up to 120 °C and add (0.1 - 1) part of lithium hydroxide. Heat up to 250 °C and react for (1 - 3) h. After the alcoholysis is completed, cool down to below 80 °C. Add (20 - 35) parts of oleic acid, (5 - 10) parts of pentaerythritol, (10 - 15) parts of phthalic anhydride, (5 - 10) parts of tetrahydrophthalic anhydride and (0.05 - 1) part of catalyst. Heat up to 150 °C ± 5 °C, keep warm for 1 h, then heat up to 180 °C ± 5 °C and keep warm for 1 h, then rise to 210 °C ± 5 °C and keep warm for 1 h. Cool down to below 180 °C and add xylene, then heat up to 220 °C ± 5 °C and reflux until the acid value is below 15 mgKOH / g. Cool down and add (0.5 - 1.5) parts of itaconic acid, and continue to reflux at 220 °C ± 5 °C until the acid value drops below 10 mgKOH / g. After vacuum pumping, add (10 - 20) parts of propylene glycol monobutyl ether and stir evenly to obtain; Step 2: Prepare the graphene modified emulsifier Add (45 - 55) parts of polyethylene glycol, (10 - 20) parts of tung oil acid, (1 - 10) parts of glycerol, (10 - 20) parts of phthalic anhydride, (5 - 10) parts of benzoic acid into a reactor equipped with a stirring device, a reflux condenser, a temperature control device and a vacuum pumping device. Heat up to 150 °C ± 5 °C, keep warm for 1 h, then heat up to 180 °C ± 5 °C and keep warm for 1 h, then rise to 210 °C ± 5 °C and keep warm until clear. Add xylene and heat up to 220 °C ± 5 °C and reflux until the acid value is 20 mgKOH / g; Cool down to 180 °C ± 5 °C and add (3 - 5) parts of polyethylene glycol diglycidyl ether. Keep warm until the acid value remains unchanged, then vacuum pump to remove xylene. Cool down and add (5 - 15) parts of propylene glycol monobutyl ether to dilute and disperse to obtain the alkyd resin reactive emulsifier A; Add (60 - 75) parts of the alkyd resin reactive emulsifier A and (25 - 40) parts of the amino graphene oxide dispersion into a reaction kettle, heat up to 50 °C - 60 °C and stir at high speed for (1 - 2) h to obtain; Step 3: Prepare the modified rheology modifier Put 50 parts of rosin powder, 38 parts of tetrahydrofuran, 2 parts of p-toluenesulfonic acid, and 10 parts of SQ-NFC3L2 nanocellulose with a solid content of 2.5% into a reactor equipped with a stirring device, a reflux condenser, a temperature control device, and a vacuum pumping device. Heat up to 155°C ± 5°C, keep the temperature for reaction for 15 hours, and then cool down for standby; Step 4: Prepare a low-VOC and high-flash-point bio-based alkyd enamel Put (50 - 70) parts of bio-based high-flash-point alkyd resin, (0.1 - 0.5) parts of potassium hydroxide, and (0.1 - 0.5) parts of dimethyldiethanolamine into a high-speed mixer with a rotation speed of (1000 - 1500) r / min. Heat up to 60°C - 70°C, add (5 - 15) parts of graphene-modified emulsifier, keep the temperature for dispersion for 20 minutes, and then slowly add (10 - 20) parts of deionized water within 30 minutes until phase inversion occurs. Adjust the rotation speed to (1500 - 2000) r / min and disperse at high speed for 30 minutes, then cool down to room temperature. Add (2 - 5) parts of dispersant, (10 - 20) parts of pigment, (0.1 - 0.5) parts of leveling agent, (0.5 - 2) parts of dryer, and (1 - 5) parts of modified rheology agent in sequence. After dispersion and grinding, add (2 - 6) parts of solvent to adjust the viscosity, and filter to obtain a low-VOC and high-flash-point bio-based alkyd enamel with a viscosity of 80 ± 10 s (ISO No. 6 cup, 23°C), a solid content of 65% ± 5%, a flash point > 61°C, and a VOC ≤ 350 g / L.

3. The low-VOC high-flash-point bio-based alkyd enamel according to claim 1 or 2, characterized in that: The vegetable oil is one or both of perilla oil and prickly ash oil with an iodine value (gI2 / 100g) between 125 and 140.

4. The low-VOC high-flash-point bio-based alkyd enamel according to claim 1 or 2, wherein: The vegetable oil acid is one or both of tung oil acid and linolenic acid with an iodine value (gI2 / 100g) between 140 and 200.

5. The low-VOC high-flash-point bio-based alkyd enamel according to claim 1 or 2, characterized in that: The polyethylene glycol is one of polyethylene glycol 4000 and polyethylene glycol 6000.

6. The low-VOC high-flash-point bio-based alkyd enamel according to claim 1 or 2, characterized in that: The polyethylene glycol diglycidyl ether is selected from one with a molecular weight of 500 - 1000.

7. The low-VOC and high-flash-point bio-based alkyd enamel according to claim 1 or 2, characterized in that: The amino graphene oxide dispersion is polyethylene glycol-amino-modified amino graphene.

8. The low-VOC high-flash-point bio-based alkyd enamel according to claim 1 or 2, characterized in that: The leveling agent is one of BYK-310, BYK-306, and EFKA-3033.

9. The low-VOC high-flash-point bio-based alkyd enamel according to claim 1 or 2, characterized in that: The dispersant is a bio-based dispersant, such as one or two of dispersant NNO, dispersant M-9, and dispersant MF.

10. The low-VOC high-flash-point bio-based alkyd enamel according to claim 1 or 2, characterized in that: The dryer is one or two of SDJ9903, SDJT-12, SDJ 9902, and SDJT-20.

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