A bio-based hydroxy polyacrylate dispersion and its preparation method and application

Abstract

The present invention belongs to the technical field of coatings, and discloses a bio-based hydroxy polyacrylate dispersion, a preparation method and application thereof. The raw material components used in the preparation method include acrylic monomers, acrylate monomers, vinyl-containing monomers, and bio-based chain extenders; the bio-based chain extender is a vegetable oil containing three or more epoxy groups, and the bio-based chain extender participates in the reaction at a temperature above 140°C to obtain a bio-based hydroxy polyacrylate dispersion. The bio-based hydroxy polyacrylate dispersion has a solid content of more than 45% by mass fraction. The bio-based hydroxy polyacrylate dispersion is applied to a two-component polyurethane coating to improve the physical properties of the paint film formed by the coating, such as chemical resistance and water resistance. The vegetable oil containing three or more epoxy groups participates in the reaction as a bio-based chain extender to obtain a product with a large molecular weight and a branched structure, which can promote the formation of a network structure product and increase the drying speed of the paint film.

Description

Technical Field

[0001] The present invention belongs to the technical field of coatings, and in particular relates to a bio-based hydroxy polyacrylate dispersion and a preparation method and application thereof. Background Art

[0002] Paint is applied to the surface of an object to protect, decorate or perform other functions on the object. Existing wood coatings are mostly solvent-based coatings (also called oil-based coatings), which contain more than 50% organic solvents. These solvents will evaporate into the atmosphere during the construction process, polluting the environment and damaging human health. In addition, the organic solvents themselves will bring potential safety hazards. Therefore, the water-based nature of wood coatings is a trend in the development of international coatings. Water-based wood coatings include single-component and two-component water-based wood coatings. Among them, the film properties of single-component water-based wood coatings, such as water resistance, chemical resistance and hardness, are quite different from those of oil-based coatings, which seriously limits the promotion and application of water-based wood coatings. The mechanical properties, water resistance and chemical resistance of two-component water-based wood coatings are comparable to those of oil-based coatings, overcoming the shortcomings of single-component water-based wood coatings.

[0003] Two-component waterborne polyurethane coatings have excellent coating properties and have been widely studied and applied. They are composed of waterborne polymer polyols and waterborne polyisocyanate curing agents, which are packaged separately and mixed in proportion when used. Waterborne polymer polyols include waterborne polyacrylate polyols, waterborne polyurethane polyols, waterborne polyester polyols, polyether polyols and mixed polyols. Among them, waterborne polyacrylate polyols have excellent color retention, gloss retention and weather resistance, low price, and easy adjustment of molecular weight, glass transition temperature and hydroxyl content. They are the first choice of waterborne polymer polyols in two-component waterborne polyurethane coatings. Two types of polyacrylate polyols, emulsion and dispersion, can be prepared by different polymerization processes. The production process of emulsion polyacrylate polyols is simple and the cost is low, but it has low hydroxyl content, and the paint film obtained by mixing with waterborne polyisocyanate curing agents has poor transparency, poor leveling, poor chemical resistance, low hardness and other problems. In contrast, the hydroxyl content of dispersed polyacrylate polyols is higher. The paint film produced by mixing with water-based polyisocyanate curing agent has high transparency, good leveling, and excellent water resistance and chemical resistance. Therefore, dispersed polyacrylate polyols have greater room for development in the future.

[0004] Dispersion-type polyacrylate polyols are also called hydroxy polyacrylate dispersions, or hydroxypropylene dispersions for short. Existing hydroxy polyacrylate dispersions still have problems such as low solid content, poor storage stability, poor milky white appearance, poor water resistance, and poor chemical resistance. In addition, the paint film obtained after mixing with a water-based polyisocyanate curing agent has problems such as slow drying speed and low hardness. The main reason for the above problems is that the polymer macromolecules of the hydroxy polyacrylate dispersion are linear structures and have a small molecular weight. When the conventional synthesis process is used to increase the molecular weight of the polymer by adjusting the amount of initiator or chain transfer agent added, the viscosity of the hydroxy polyacrylate dispersion prepolymer will increase significantly, which is not conducive to dispersion by adding water, and in severe cases, prepolymer gel will appear.

[0005] Moreover, most of the two-component waterborne polyurethane coatings on the market use petroleum-based hydroxy polyacrylate dispersions, which is not environmentally friendly.

[0006] Therefore, there is an urgent need to provide a new hydroxy polyacrylate dispersion. Summary of the invention

[0007] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention provides a bio-based hydroxy polyacrylate dispersion and a preparation method and application thereof, wherein the bio-based hydroxy polyacrylate dispersion is applied to a two-component polyurethane coating, and the formed paint film has good water resistance, chemical resistance, high hardness, and fast drying speed.

[0008] The inventive concept of the present invention is as follows: the raw material components for preparing the bio-based hydroxy polyacrylate dispersion of the present invention include acrylic monomers, acrylate monomers, vinyl-containing monomers, and bio-based chain extenders, and the bio-based chain extender is a vegetable oil containing three or more epoxy groups. The bio-based chain extender is added before the prepolymer is dispersed, which can reduce the viscosity of the hydroxy polyacrylate prepolymer, thereby improving the dispersion effect of the bio-based hydroxy polyacrylate prepolymer. The bio-based chain extender participates in the reaction at a high temperature of more than 140°C, and the epoxy group in the bio-based chain extender undergoes a ring-opening reaction with the carboxyl group of the hydroxy polyacrylate prepolymer. The prepolymer is chain extended in the latex particles to generate hydroxyl groups, which is beneficial to improve the storage stability of the dispersion. The bio-based hydroxy polyacrylate dispersion is applied to a two-component polyurethane coating to improve the physical properties of the paint film, such as chemical resistance and water resistance. Moreover, the vegetable oil containing three or more epoxy groups participates in the reaction as a bio-based chain extender, and a product with a large molecular weight and a branched structure can be obtained, which can promote the formation of a network structure product and improve the drying speed of the paint film.

[0009] The preparation method of the bio-based hydroxy polyacrylate dispersion of the present invention involves a bio-based hydroxy polyacrylate dispersion prepolymer in the reaction process, and the prepolymer is dispersed at low viscosity, and each latex particle is made into a microreactor. The chain extension reaction of the bio-based chain extender is carried out inside the latex particle, which not only ensures the stability of the dispersion process, but also ensures the storage stability of the bio-based hydroxy polyacrylate dispersion, and the obtained bio-based hydroxy polyacrylate dispersion has a high solid content and good appearance.

[0010] The present invention also provides a two-component polyurethane coating. The paint film prepared by mixing the bio-based hydroxy polyacrylate dispersion and the water-based polyisocyanate curing agent has a fast drying speed and high hardness. The obtained water-based two-component polyurethane paint film has the advantages of high gloss, high transparency, excellent water resistance and chemical resistance, high crosslinking density, high hardness, scratch resistance and wear resistance. It can be applied to high-end wood coatings, automotive coatings, metal anti-corrosion coatings and other industrial protective coatings.

[0011] A first aspect of the present invention provides a method for preparing a bio-based hydroxy polyacrylate dispersion.

[0012] Specifically, a method for preparing a bio-based hydroxy polyacrylate dispersion, wherein the raw material components used in the preparation method include acrylic monomers, acrylic ester monomers, vinyl-containing monomers, and bio-based chain extenders;

[0013] The bio-based chain extender is a vegetable oil containing three or more epoxy groups, and the bio-based chain extender participates in the reaction at a temperature above 140° C. to prepare the bio-based hydroxy polyacrylate dispersion.

[0014] Preferably, the raw material components used in the preparation method also include an initiator, an active diluent, a neutralizer, and water.

[0015] Preferably, the preparation method comprises the following steps:

[0016] The acrylic monomer, the acrylate monomer, the vinyl-containing monomer, and the initiator are mixed to form a mixed solution;

[0017] The active diluent is heated to 135-155° C., then dripped into the mixed solution, stirred, kept warm, then cooled to 70-85° C., the bio-based chain extender, neutralizer, and water are added, dispersed, and then reacted at a temperature above 160° C. for 40-80 minutes to obtain the bio-based hydroxy polyacrylate dispersion.

[0018] Preferably, after adding the bio-based chain extender, the reaction is carried out at 160-175° C. for 45-75 minutes.

[0019] Preferably, the acrylic monomer is selected from at least one of acrylic acid or methacrylic acid.

[0020] Preferably, the acrylic acid ester monomers include hydroxy acrylic acid ester monomers and at least one of methyl methacrylate, butyl acrylate, isobornyl acrylate, cyclohexyl methacrylate or benzyl methacrylate.

[0021] Preferably, the hydroxyacrylate monomer is selected from at least one of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate or hydroxypropyl methacrylate.

[0022] Preferably, the vinyl-containing monomer comprises styrene.

[0023] Preferably, the initiator is selected from at least one of di-tert-amyl hydroperoxide and di-tert-butyl hydroperoxide.

[0024] Preferably, the reactive diluent is a substance containing one epoxy group and no double bonds. The reactive diluent without double bonds is added to the reaction vessel as a primer. The absence of double bonds ensures that it does not react at about 150°C, nor does it undergo free radical polymerization with the acrylate monomer. In the past, free radical polymerization used solvent as a primer to allow the substances in the reaction vessel to be stirred and reacted normally. The reactive diluent containing an epoxy group in the present invention is used as a primer, which can gradually react with the carboxyl group on the main chain of the hydroxy polyacrylate polymer to finally achieve solvent-free polymerization. The reactive diluent contains only one epoxy group, which ensures that the prepolymer does not form a cross-linked structure during the prepolymerization stage, thereby facilitating the dispersion of the prepolymer.

[0025] Preferably, the active diluent is selected from at least one of versatile glycidyl carbonate, 4-tert-butylbenzoic acid glycidyl ester and p-toluenesulfonic acid glycidyl ester.

[0026] Preferably, the bio-based chain extender is selected from at least one of epoxidized soybean oil or epoxidized linseed oil.

[0027] Further preferably, the bio-based chain extender is GreenSoft D special epoxy soybean oil, GreenSoft H special epoxy soybean oil, epoxy linseed oil ELO At least one of 9-5TM.

[0028] Preferably, the neutralizing agent is a tertiary amine substance; further preferably, the neutralizing agent is selected from at least one of triethylamine, N,N-dimethylethanolamine or N,N-dimethylcyclohexylamine.

[0029] Preferably, the preparation method comprises the following steps:

[0030] By weight, 10-28 parts of acrylic monomer, 30-58 parts of acrylate monomer, 12-25 parts of vinyl-containing monomer, and 1-3.5 parts of initiator are mixed evenly to form a mixed solution;

[0031] In parts by mass, 20-40 parts of active diluent are heated to 135-155° C. and then dripped into the mixed solution at constant pressure within 2-5 hours. After dripping, the mixture is stirred and kept warm for 20-40 minutes, cooled to 70-85° C., 8-25 parts of bio-based chain extender and 3.0-5.3 parts of neutralizer are added, stirred for 3-5 minutes, and then 135-150 parts of water are added for dispersion for 3-5 minutes, transferred to a reactor, pressurized to 2-2.5 MPa, heated to 160-185° C., reacted for 40-85 minutes, and the reaction was stopped after the epoxy value of the product was less than 0.005 determined by the hydrochloric acid-acetone method, cooled to below 40° C., depressurized, and filtered to obtain the bio-based hydroxy polyacrylate dispersion.

[0032] Further preferably, the preparation method comprises the following steps:

[0033] By weight, 15-22 parts of acrylic monomer, 34-53 parts of acrylate monomer, 15-20 parts of vinyl-containing monomer, and 1.5-2.5 parts of initiator are mixed evenly to form a mixed solution;

[0034] In parts by mass, 25-31 parts of active diluent are heated to 140-150° C. and then dripped into the mixed solution at constant pressure within 4-5 hours. After dripping, the mixture is stirred and kept warm for 20-30 minutes, cooled to 75-80° C., 10-20 parts of bio-based chain extender and 3.2-4.3 parts of neutralizer are added, stirred for 3-5 minutes, and then 135-150 parts of water are added for dispersion for 3-5 minutes, transferred to a high-pressure reactor, pressurized to 2-2.5 MPa, heated to 160-175° C., reacted for 45-75 minutes, and the reaction was stopped after the epoxy value was less than 0.005 determined by the hydrochloric acid-acetone method, cooled to below 40° C., depressurized, and filtered to obtain the bio-based hydroxy polyacrylate dispersion.

[0035] Preferably, the 34-53 parts of acrylic ester monomers include 9-20 parts of hydroxy acrylic ester monomers.

[0036] Before adding the bio-based chain extender, a bio-based hydroxy polyacrylate dispersion prepolymer is generated in the system. The present invention adds a bio-based chain extender before the hydroxy polyacrylate dispersion prepolymer is dispersed. At this time, the bio-based chain extender can play a role in reducing viscosity, so that the hydroxy polyacrylate dispersion prepolymer can be dispersed at a low viscosity, avoiding the problem that the prepolymer has a high viscosity and is difficult to disperse when the polymer molecular weight is too large. At the same time, each latex particle after dispersion becomes a microreactor, and the post-chain extension reaction is carried out inside the latex particle, which not only ensures the stability of the dispersion process, but also ensures the storage stability of the bio-based hydroxy polyacrylate dispersion, and solves the problems of low solid content of the hydroxy polyacrylate dispersion, poor milky white appearance, and slow drying speed and low hardness of the paint film obtained after mixing with the water-based polyisocyanate curing agent.

[0037] A second aspect of the present invention provides a bio-based hydroxy polyacrylate dispersion.

[0038] Specifically, a bio-based hydroxy polyacrylate dispersion is prepared by the above preparation method.

[0039] Preferably, the biobased content of the biobased hydroxypolyacrylate dispersion is ≥5%;

[0040] Preferably, the pH of the bio-based hydroxy polyacrylate dispersion is 7.5-8, and weak alkalinity is beneficial to improving the storage stability of the dispersion.

[0041] Preferably, the particle size of the bio-based hydroxy polyacrylate dispersion is less than 110 nm, so that the appearance of the dispersion can achieve a semi-transparent effect.

[0042] Preferably, the bio-based hydroxy polyacrylate dispersion has a solid content greater than 45%, preferably 45-48%, by mass fraction, which is higher than the 40% solid content of mainstream products on the market.

[0043] Preferably, the hydroxyl content of the bio-based hydroxy polyacrylate dispersion is 3.6%-4.5% by mass, which is a high hydroxyl content product and is beneficial to improving the water resistance and medium resistance of the bio-based two-component waterborne polyurethane paint film.

[0044] A third aspect of the present invention provides a two-component polyurethane coating.

[0045] Specifically, a two-component polyurethane coating includes an agent A and an agent B;

[0046] The agent A includes the above-mentioned bio-based hydroxy polyacrylate dispersion;

[0047] The B agent includes a water-based polyisocyanate curing agent;

[0048] The molar ratio of NCO in the B agent to OH in the A agent is 1.0-2.0:1.

[0049] Preferably, the molar ratio of NCO in the B agent to OH in the A agent is 1.0-1.8:1.

[0050] Preferably, a two-component polyurethane coating comprises agent A and agent B;

[0051] The A agent comprises the following components in parts by weight:

[0052]

[0053]

[0054] The B agent includes 20-30 parts of water-based polyisocyanate curing agent.

[0055] Preferably, a two-component polyurethane coating comprises agent A and agent B;

[0056] The A agent comprises the following components in parts by weight:

[0057]

[0058] The B agent includes 20-30 parts of water-based polyisocyanate curing agent.

[0059] Preferably, the film-forming aid is at least one of propylene glycol methyl ether, propylene glycol butyl ether, dipropylene glycol methyl ether or dipropylene glycol butyl ether.

[0060] Preferably, the defoamer is at least one of TEGO's polyether siloxane copolymer defoamers TEGO-800, TEGO-805, TEGO-815, TEGO-825 or BYK's modified polysiloxane copolymer solutions BYK-019 and BYK-020.

[0061] Preferably, the thickener is at least one of DOW's nonionic polyurethane associative thickener RM-8W, hydrophobically modified alkali-swellable associative thickener TT-935, alkali-swellable non-associative thickener ASE-60 and TEGO's nonionic associative thickeners TEGO ViscoPlus 3000, TEGO ViscoPlus 3030, and TEGO ViscoPlus 3060.

[0062] Preferably, the wetting agent is at least one of TEGO's polyether siloxane copolymer TEGO-245, nonionic organic surfactant TEGO-500, or BYK's polyether modified polysiloxane solution BYK-346.

[0063] Preferably, the neutralizing agent is at least one of triethylamine, dimethylethanolamine and triethanolamine.

[0064] Preferably, the waterborne polyisocyanate curing agent includes at least one of sulfonates, carboxylates and alkoxy hydrophilically modified hexamethylene diisocyanate (HDI).

[0065] Further preferably, the water-based polyisocyanate curing agent is at least one of Bayhydur XP 2487 / 1 and Bayhydur XP 2655 produced by Covestro.

[0066] A method for preparing a two-component polyurethane coating comprises the following steps:

[0067] After premixing water and a film-forming aid and adding them to a bio-based hydroxy polyacrylate dispersion, a defoamer, a thickener, a wetting agent and a neutralizer are added in sequence, dispersed for 10-30 minutes, and filtered to obtain Agent A;

[0068] Agent B includes a water-based polyisocyanate curing agent;

[0069] The two-component polyurethane coating is obtained.

[0070] When the two-component polyurethane coating is applied, add agent B into agent A, stir for 5-8 minutes, and then apply.

[0071] The above two-component polyurethane coating is used in the field of wood, automobile or metal corrosion protection.

[0072] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0073] (1) The raw material components for preparing the bio-based hydroxy polyacrylate dispersion of the present invention include acrylic monomers, acrylate monomers, vinyl-containing monomers, and bio-based chain extenders, and the bio-based chain extender is a vegetable oil containing three or more epoxy groups. The bio-based chain extender is added before the prepolymer is dispersed, which can reduce the viscosity of the hydroxy polyacrylate prepolymer and thus improve the dispersion effect of the bio-based hydroxy polyacrylate prepolymer. The bio-based chain extender participates in the reaction at a high temperature above 140°C, and the epoxy group in the bio-based chain extender undergoes a ring-opening reaction with the carboxyl group of the hydroxy polyacrylate prepolymer. The prepolymer is chain extended in the latex particles to generate hydroxyl groups, which is beneficial to improve the storage stability of the dispersion. The bio-based hydroxy polyacrylate dispersion is applied to a two-component polyurethane coating to improve the physical properties of the paint film, such as chemical resistance and water resistance. Moreover, the vegetable oil containing three or more epoxy groups participates in the reaction as a bio-based chain extender to obtain a product with a large molecular weight and a branched structure, which can promote the formation of a network structure product and improve the drying speed of the paint film.

[0074] (2) The bio-based hydroxy polyacrylate dispersion has the characteristics of large molecular weight, branched structure, good storage stability, good appearance and high solid content; and the preparation method of the bio-based hydroxy polyacrylate dispersion has the advantages of simple operation, easy control and low cost, and can prepare bio-based hydroxy polyacrylate dispersion in batches. DETAILED DESCRIPTION

[0075] In order to make the technical scheme of the present invention more clearly understood by those skilled in the art, the following embodiments are listed for illustration. It should be pointed out that the following embodiments do not limit the protection scope of the present invention.

[0076] Unless otherwise specified, the raw materials, reagents or devices used in the following examples can be obtained from conventional commercial sources or by existing known methods.

[0077] The bio-based chain extenders used in the following examples are GreenSoft D special epoxy soybean oil, GreenSoft H special epoxy soybean oil, and epoxy linseed oil ELO produced by Xingbang Polymer Materials Co., Ltd. A type of 9-5TM.

[0078] The defoamer is the polyether siloxane copolymer defoamer TEGO-800, TEGO-805, TEGO-815, TEGO-825 produced by TEGO or the modified polysiloxane copolymer solution BYK-019, BYK-020 produced by BYK.

[0079] The thickeners are DOW's nonionic polyurethane associative thickener RM-8W, hydrophobically modified alkali-swellable associative thickener TT-935, alkali-swellable non-associative thickener ASE-60 and TEGO's nonionic associative thickeners TEGOViscoPlus 3000, TEGO ViscoPlus 3030 and TEGO ViscoPlus 3060.

[0080] The wetting agent is polyether siloxane copolymer TEGO-245 from TEGO, nonionic organic surfactant TEGO-500 from TEGO or polyether modified polysiloxane solution BYK-346 from BYK.

[0081] The water-based polyisocyanate curing agent is Bayhydur XP 2487 / 1 or Bayhydur XP2655 from Covestro.

[0082] Basic performance tests include: Bio-based hydroxy polyacrylate dispersions are tested in accordance with GB / T11175-2002 "Test Methods for Synthetic Resin Emulsions", and the appearance, pH, solid content, and viscosity of bio-based hydroxy polyacrylate dispersions are tested. The average particle size of bio-based hydroxy polyacrylate dispersions is measured using a nanoparticle size analyzer (ZS Nano S).

[0083] The performance of the paint film formed by the two-component polyurethane coating is tested with reference to GB / T23999-2009 "Water-based Wood Coatings for Interior Decoration and Renovation", and the gloss, hardness, water resistance, dry heat resistance and alcohol resistance of the paint film are tested.

[0084] Example 1: Preparation of bio-based hydroxy polyacrylate dispersion and two-component polyurethane coating

[0085] A method for preparing a bio-based hydroxy polyacrylate dispersion 1 comprises the following steps:

[0086] (1) By weight, 16.3 parts of acrylic acid, 12.7 parts of methyl methacrylate, 20 parts of styrene, 8.7 parts of butyl acrylate, 10.7 parts of hydroxyethyl methacrylate, 10.6 parts of isobornyl acrylate, and 1.5 parts of di-tert-amyl peroxide were mixed uniformly to form a mixed solution;

[0087] (2) Add 30 parts of tert-butyl glycidyl carbonate monomer to a four-necked flask equipped with a thermometer, a condenser, a stirring paddle and a constant pressure dropping funnel, mix and stir and heat. When the temperature reaches 145° C., start to drop the mixed solution prepared in step (1) and complete the dropwise addition for 4 hours. After the dropwise addition is completed, stir and keep warm for 30 minutes. Cool down to 80° C., add 15 parts of GreenSoft D special epoxy soybean oil and 4.3 parts of N,N-dimethylcyclohexylamine, stir for 5 minutes, add 150 parts of deionized water and disperse at high speed for 3 minutes (the speed of high-speed dispersion is 1000 rpm), transfer to an autoclave, pressurize to 2 MPa, heat to 160° C., react for 60 minutes, stop the reaction when the epoxy value of the product is less than 0.005 as determined by the hydrochloric acid-acetone method, cool to below 40° C., release the pressure, filter and discharge the product, and obtain a bio-based hydroxy polyacrylate dispersion 1.

[0088] The bio-based hydroxy polyacrylate dispersion 1 prepared in this example has a bio-based content of 11.6%, a semi-transparent appearance, a pH of 8, a hydroxyl content of 3.6%, a solid content of 46.5%, a viscosity of 1350 cp at 25°C, an average particle size of 98 nm, and no change after heat storage at 50°C for one month.

[0089] A two-component polyurethane coating 1, comprising an agent A and an agent B;

[0090] Agent A is composed of the following components in parts by weight:

[0091]

[0092] Agent B includes 22.5 parts of a water-based polyisocyanate curing agent (Bayhydur XP 2487 / 1).

[0093] The molar ratio of NCO in agent B to OH in agent A in the two-component polyurethane coating 1 is 1.8:1.

[0094] The preparation method of agent A of the above-mentioned two-component polyurethane coating is as follows: add the bio-based hydroxy polyacrylate dispersion 1 into a stirring tank at a rotation speed of 700 rpm, premix water, dipropylene glycol butyl ether and dipropylene glycol methyl ether and add them into the stirring tank, add TEGO-800, RM-8W, TEGO-245 and TEA (triethanolamine) in sequence, disperse for 20 minutes, and filter the material.

[0095] During construction, agent B was added to agent A and stirred for 6 minutes to obtain a two-component polyurethane coating 1, whose biobased content was 6.1%.

[0096] The paint film was prepared using the two-component polyurethane coating 1 and cured and dried at room temperature for 7 days. The properties of the paint film are shown in Table 1:

[0097] Table 1: Comprehensive properties of two-component polyurethane coating 1

[0098]

[0099]

[0100] Example 2: Preparation of bio-based hydroxy polyacrylate dispersion and two-component polyurethane coating

[0101] A bio-based hydroxy polyacrylate dispersion 2 is prepared by the following steps:

[0102] (1) By weight, 21.7 parts of methacrylic acid, 10.7 parts of methyl methacrylate, 15.1 parts of styrene, 6 parts of butyl acrylate, 9.6 parts of hydroxyethyl acrylate, 9 parts of cyclohexyl methacrylate, and 2 parts of di-tert-butyl peroxide were mixed to form a mixed solution for later use;

[0103] (2) Add 31 parts of 4-tert-butylbenzoic acid glycidyl ester monomer to a four-necked flask equipped with a thermometer, a condenser, a stirring paddle and a constant pressure dropping funnel, mix, stir and heat, and when the temperature reaches 140°C, start to drop the mixed solution prepared in step (1) and complete the dropwise addition in 4.5 hours. After the dropwise addition is completed, stir and keep warm for 30 minutes, cool to 75°C, add 20 parts of GreenSoft H special epoxy soybean oil and 3.2 parts of triethylamine, stir for 3 minutes, add 139 parts of deionized water and disperse at high speed for 5 minutes, transfer to a high-pressure reactor, pressurize to 2.2 MPa, heat to 165°C, react for 75 minutes, and stop the reaction when the epoxy value is less than 0.005 as determined by the hydrochloric acid-acetone method; cool to 40°C and filter the material to obtain a bio-based hydroxy polyacrylate dispersion 2.

[0104] The bio-based hydroxy polyacrylate dispersion 2 prepared in this example has a bio-based content of 15.6%, a semi-transparent appearance, a pH of 7.5, a hydroxyl content of 4.0%, a solid content of 48%, a viscosity of 1550 cp at 25°C, an average particle size of 105 nm, and no change after heat storage at 50°C for one month.

[0105] A two-component polyurethane coating 2, comprising an agent A and an agent B;

[0106] Agent A is composed of the following components in parts by weight:

[0107]

[0108] Agent B is 25 parts of water-based polyisocyanate curing agent (Bayhydur XP 2655);

[0109] The molar ratio of NCO in agent B to OH in agent A in the two-component polyurethane coating 2 is 1.8:1.

[0110] The preparation method of agent A of the above-mentioned two-component polyurethane coating 2 is as follows: add the bio-based hydroxy polyacrylate dispersion 2 into a stirring tank at a rotation speed of 700 rpm, premix water, dipropylene glycol butyl ether and dipropylene glycol methyl ether and add them into the stirring tank, add TEGO-805, TT-935, BYK-346 and DMEA in sequence, disperse for 15 minutes, and filter the material.

[0111] During construction, agent B was added to agent A and stirred for 7 minutes to obtain a two-component polyurethane coating 2, whose biobased content was 7.8%.

[0112] The paint film prepared by the above two-component polyurethane coating 2 was cured and dried at room temperature for 7 days, and its properties are shown in Table 2.

[0113] Table 2: Comprehensive properties of two-component polyurethane coating 2

[0114] Test items performance Detection Methods Surface drying time / min 32 GB / T1728-2020 Drying time / d 3 GB / T1728-2020 Pencil hardness H GB / T6739-2006 Coating gloss / (60°,%) 91 GB / T9754-2007 Water resistance (25℃, 24h) 1. No change GB / T4893.1-2020 Dry heat resistance (70±2℃, 15h) 1. No change GB / T4893.3-2020 Ethanol resistance (50%, 1h) 1. No change GB / T4893.1-2020

[0115] Example 3: Preparation of bio-based hydroxy polyacrylate dispersion and two-component polyurethane coating

[0116] A bio-based hydroxy polyacrylate dispersion 3 is prepared by the following steps:

[0117] (1) 15.8 parts by mass of acrylic acid, 15 parts by mass of methyl methacrylate, 15 parts by mass of styrene, 5 parts by mass of butyl acrylate, 20 parts by mass of hydroxypropyl acrylate, 9.5 parts by mass of benzyl methacrylate and 2.5 parts by mass of di-tert-amyl peroxide were mixed to form a mixed solution for later use;

[0118] (2) Add 25 parts of glycidyl p-toluenesulfonate monomer to a four-necked flask equipped with a thermometer, a condenser, a stirring paddle and a constant pressure dropping funnel, mix, stir and heat, and when the temperature reaches 150°C, start to drop the mixed solution prepared in step (1) and complete the dropwise addition in 5 hours. After the dropwise addition is completed, stir and keep warm for 20 minutes, cool to 75°C, add 10 parts of epoxy linseed oil and 4.2 parts of N,N-dimethylethanolamine, stir for 5 minutes, add 150 parts of deionized water and disperse at high speed for 5 minutes, transfer to a high-pressure reactor, pressurize to 2.5 MPa, heat to 175°C, react for 45 minutes, and stop the reaction when the epoxy value is less than 0.005 as determined by the hydrochloric acid-acetone method; cool to 40°C and filter the material to obtain a bio-based hydroxy polyacrylate dispersion 3.

[0119] The bio-based hydroxy polyacrylate dispersion 3 prepared in this example has a bio-based content of 8.2%, a semi-transparent appearance, a pH of 8, a hydroxyl content of 4.5%, a solid content of 45%, a viscosity of 1300 cp at 25°C, an average particle size of 100 nm, and no change after heat storage at 50°C for one month.

[0120] A two-component polyurethane coating 3,

[0121] Includes dose A and dose B;

[0122] Agent A is composed of the following components in parts by weight:

[0123]

[0124] Agent B is 28.5 parts of water-based polyisocyanate curing agent (Bayhydur XP 2487 / 1);

[0125] The molar ratio of NCO in agent B to OH in agent A in the two-component polyurethane coating 3 is 1.8:1.

[0126] The preparation method of agent A of the above-mentioned two-component polyurethane coating 3 is as follows: add the hydroxy polyacrylate dispersion 3 into a stirring tank at a rotation speed of 700 rpm, premix water, propylene glycol methyl ether and dipropylene glycol butyl ether and add them into the stirring tank, add TEGO-815, TEGO ViscoPlus 3000, TEGO-500 and TEA in sequence, disperse for 30 minutes, and filter the material.

[0127] During construction, agent B was added to agent A and stirred for 8 minutes to obtain a two-component polyurethane coating 3, whose biobased content was 3.9%.

[0128] The two-component polyurethane coating 3 was prepared into a paint film, which was cured and dried at room temperature for 7 days. The properties of the paint film are shown in Table 3.

[0129] Table 3: Comprehensive properties of two-component polyurethane coating 3

[0130]

[0131]

[0132] Comparative Example 1

[0133] A method for preparing a hydroxy polyacrylate dispersion 4 comprises the following steps:

[0134] (1) By weight, 16.3 parts of acrylic acid, 12.7 parts of methyl methacrylate, 20 parts of styrene, 8.7 parts of butyl acrylate, 10.7 parts of hydroxyethyl methacrylate, 10.6 parts of isobornyl acrylate, and 1.5 parts of di-tert-amyl peroxide were mixed uniformly to form a mixed solution;

[0135] (2) Add 30 parts of tert-butyl glycidyl carbonate monomer to a four-necked flask equipped with a thermometer, a condenser, a stirring paddle and a constant pressure dropping funnel, stir and heat, and when the temperature reaches 145°C, start to drop the mixed solution prepared in step (1) and complete the dropwise addition within 4 hours. After the dropwise addition is completed, stir and keep warm for 30 minutes, cool to 80°C, add 4.3 parts of N,N-dimethylcyclohexylamine, stir for 5 minutes, add 150 parts of deionized water and disperse at high speed for 3 minutes, transfer to a high-pressure reactor, pressurize to 2 MPa, heat to 160°C, react for 60 minutes, stop the reaction when the epoxy value of the product is less than 0.005 as determined by the hydrochloric acid-acetone method, cool to below 40°C, release the pressure, filter and discharge the product, and obtain hydroxy polyacrylate dispersion 4.

[0136] The hydroxy polyacrylate dispersion 4 prepared in this comparative example has a biobased content of 0%, a semi-transparent appearance, a pH of 5, a hydroxyl content of 3.2%, a solid content of 43.3%, a viscosity of 1650 cp at 25°C, an average particle size of 85 nm, and gelation after heat storage at 50°C for 1 month.

[0137] The difference between this comparative example and Example 1 is that GreenSoft D special epoxy soybean oil is not added in this comparative example. Compared with Example 1, the biobased content of the hydroxy polyacrylate dispersion 4 prepared in Comparative Example 1 is 0%, the pH is acidic, the hydroxyl content is low, the solid content is low, and the thermal storage stability is poor. The reason for the above problems is that the epoxy soybean oil is not added to react with the carboxyl group of the hydroxy polyacrylate polymer, and the residual carboxyl content of the polymer is too high.

[0138] A two-component polyurethane coating 4, comprising an agent A and an agent B;

[0139] Agent A is composed of the following components in parts by weight:

[0140]

[0141]

[0142] Agent B includes 18.6 parts of a water-based polyisocyanate curing agent (Bayhydur XP 2487 / 1).

[0143] The molar ratio of NCO in agent B to OH in agent A in the two-component polyurethane coating 4 is 1.8:1.

[0144] The preparation method of agent A of the above-mentioned two-component polyurethane coating 4 is as follows: add the hydroxy polyacrylate dispersion 4 into a stirring tank at a rotation speed of 700 rpm, premix water, dipropylene glycol butyl ether and dipropylene glycol methyl ether and add them into the stirring tank, add TEGO-800, RM-8W, TEGO-245 and TEA (triethanolamine) in sequence, disperse for 20 minutes, and filter the material.

[0145] During construction, agent B was added to agent A and stirred for 6 minutes to obtain a two-component polyurethane coating 4, whose bio-based content was 0%.

[0146] The paint film was prepared using two-component polyurethane coating 4 and cured and dried at room temperature for 7 days. The properties of the paint film are shown in Table 4:

[0147] Table 4: Comprehensive properties of two-component polyurethane coating 4

[0148] Test items performance Detection Methods Surface drying time / min 75 GB / T1728-2020 Drying time / d 4 GB / T1728-2020 Pencil hardness 3B GB / T6739-2006 Coating gloss / (60°,%) 95 GB / T9754-2007 Water resistance (25℃, 24h) 4. Severe marks GB / T4893.1-2020 Dry heat resistance (70±2℃, 15h) 4. Severe marks GB / T4893.3-2020 Ethanol resistance (50%, 1h) 4. Severe marks GB / T4893.1-2020

[0149] It can be seen from the above table that the two-component polyurethane coating 4 of this comparative example has longer surface drying and actual drying time than the bio-based two-component polyurethane coating 1 of Example 1, which is not conducive to improving construction efficiency. The pencil hardness, water resistance, dry heat resistance and ethanol resistance of the paint film are far inferior to those of Example 1.

[0150] Comparative Example 2

[0151] A method for preparing a hydroxy polyacrylate dispersion 5 comprises the following steps:

[0152] (1) By weight, 11.7 parts of acrylic acid, 15.7 parts of methyl methacrylate, 20 parts of styrene, 17 parts of butyl acrylate, 19 parts of hydroxyethyl methacrylate, 10.6 parts of isobornyl acrylate, and 1.5 parts of di-tert-amyl peroxide were mixed uniformly to form a mixed solution;

[0153] (2) Add 30 parts of tert-butyl glycidyl carbonate monomer to a four-necked flask equipped with a thermometer, a condenser, a stirring paddle and a constant pressure dropping funnel, stir and heat, and when the temperature reaches 145°C, start to drop the mixed solution prepared in step (1) and complete the dropwise addition within 4 hours. After the dropwise addition is completed, stir and keep warm for 30 minutes, cool to 80°C, add 4.3 parts of N,N-dimethylcyclohexylamine, stir for 5 minutes, add 150 parts of deionized water and disperse at high speed for 3 minutes, transfer to a high-pressure reactor, pressurize to 2 MPa, heat to 160°C, react for 60 minutes, stop the reaction when the epoxy value of the product is less than 0.005 as determined by the hydrochloric acid-acetone method, cool to below 40°C, release the pressure, filter and discharge the product, and obtain hydroxy polyacrylate dispersion 5.

[0154] The hydroxy polyacrylate dispersion 5 prepared in this comparative example has a biobased content of 0%, a semi-transparent appearance, a pH of 8, a hydroxyl content of 3.6%, a solid content of 46.5%, a viscosity of 1550 cp at 25°C, an average particle size of 108 nm, and no change after heat storage at 50°C for one month.

[0155] This comparative example is a hydroxy polyacrylate dispersion synthesized according to a conventional process without adding bio-based materials, and its hydroxyl content and solid content parameters are consistent with those of Example 1. Compared with Example 1, no chain extender is added in Comparative Example 2.

[0156] A two-component polyurethane coating 5, comprising an agent A and an agent B;

[0157] Agent A is composed of the following components in parts by weight:

[0158]

[0159] Agent B includes 22.5 parts of a water-based polyisocyanate curing agent (Bayhydur XP 2487 / 1).

[0160] The molar ratio of NCO in agent B to OH in agent A in the two-component polyurethane coating 5 is 1.8:1.

[0161] The preparation method of agent A of the above-mentioned two-component polyurethane coating 5 is as follows: add the hydroxy polyacrylate dispersion 5 into a stirring tank at a rotation speed of 700 rpm, premix water, dipropylene glycol butyl ether and dipropylene glycol methyl ether and add them into the stirring tank, add TEGO-800, RM-8W, TEGO-245 and TEA (triethanolamine) in sequence, disperse for 20 minutes, and filter the material.

[0162] During construction, agent B was added to agent A and stirred for 6 minutes to obtain a two-component polyurethane coating 5, whose bio-based content was 0%.

[0163] The paint film was prepared using the two-component polyurethane coating 5 and cured and dried at room temperature for 7 days. The properties of the paint film are shown in Table 5:

[0164] Table 5: Comprehensive properties of two-component polyurethane coating 5

[0165] Test items performance Detection Methods Surface drying time / min 90 GB / T1728-2020 Drying time / d 5 GB / T1728-2020 Pencil hardness 2B GB / T6739-2006 Coating gloss / (60°,%) 97 GB / T9754-2007 Water resistance (25℃, 24h) 4. Severe marks GB / T4893.1-2020 Dry heat resistance (70±2℃, 15h) 4. Severe marks GB / T4893.3-2020 Ethanol resistance (50%, 1h) 4. Severe marks GB / T4893.1-2020

[0166] It can be seen from the above table that the two-component polyurethane coating 5 of this comparative example has longer surface drying and actual drying time than the bio-based two-component polyurethane coating 1 of Example 1, which is not conducive to improving construction efficiency. The pencil hardness, water resistance, dry heat resistance and ethanol resistance of the paint film are far inferior to those of Example 1.

[0167] Comparative Example 3

[0168] A method for preparing a bio-based hydroxy polyacrylate dispersion 6 comprises the following steps:

[0169] (1) By weight, 22.2 parts of acrylic acid, 9.2 parts of methyl methacrylate, 14.5 parts of styrene, 6.3 parts of butyl acrylate, 7.6 parts of isobornyl acrylate, and 1.5 parts of di-tert-amyl peroxide were mixed uniformly to form a mixed solution;

[0170] (2) Add 30 parts of tert-butyl glycidyl carbonate monomer to a four-necked flask equipped with a thermometer, a condenser, a stirring paddle and a constant pressure dropping funnel, mix, stir and heat. When the temperature reaches 145°C, start to drop the mixed solution prepared in step (1) and complete the dropwise addition within 4 hours. After the dropwise addition is completed, stir and keep warm for 30 minutes. Cool down to 80°C, add 34.2 parts of GreenSoft D epoxy soybean oil and 4.3 parts of N,N-dimethylcyclohexylamine, stir for 5 minutes, add 150 parts of deionized water and disperse at high speed for 3 minutes, transfer to an autoclave, pressurize to 2 MPa, heat to 160°C, react for 60 minutes, stop the reaction when the epoxy value of the product is less than 0.005 as determined by the hydrochloric acid-acetone method, cool to below 40°C, release the pressure, filter and discharge the product, and obtain a bio-based hydroxy polyacrylate dispersion 6.

[0171] The bio-based hydroxy polyacrylate dispersion 6 prepared in this comparative example has a bio-based content of 26.3%, a semi-transparent appearance, a pH of 8, a hydroxyl content of 3.6%, a solid content of 46.5%, a viscosity of 1250 cp at 25°C, an average particle size of 103 nm, and stratification after heat storage at 50°C for 1 month.

[0172] The hydroxyl content and solid content parameters of the bio-based hydroxy polyacrylate dispersion of this comparative example are consistent with those of Example 1, but hydroxyethyl methacrylate is not added, and the hydroxyl group is only generated by the reaction of epoxidized soybean oil and carboxyl groups. Compared with Example 1, the bio-based content of Comparative Example 3 is higher, at 26.3%, but the thermal storage stability is poor. The reason for the above problems is that the amount of epoxidized soybean oil added is too high and the cross-linking density of the polymer is too large.

[0173] A two-component polyurethane coating 6, comprising an agent A and an agent B;

[0174] Agent A is composed of the following components in parts by weight:

[0175]

[0176] Agent B includes 22.5 parts of a water-based polyisocyanate curing agent (Bayhydur XP 2487 / 1).

[0177] The molar ratio of NCO in agent B to OH in agent A in the two-component polyurethane coating 6 is 1.8:1.

[0178] The preparation method of agent A of the above-mentioned two-component polyurethane coating 6 is as follows: add the bio-based hydroxy polyacrylate dispersion 6 into a stirring tank at a rotation speed of 700 rpm, premix water, dipropylene glycol butyl ether and dipropylene glycol methyl ether and add them into the stirring tank, add TEGO-800, RM-8W, TEGO-245 and TEA (triethanolamine) in sequence, disperse for 20 minutes, and filter the material.

[0179] During construction, agent B was added to agent A and stirred for 6 minutes to obtain a two-component polyurethane coating 6, whose biobased content was 13.9%.

[0180] The paint film was prepared using two-component polyurethane coating 6 and cured and dried at room temperature for 7 days. The properties of the paint film are shown in Table 6:

[0181] Table 6: Comprehensive properties of two-component polyurethane coating 6

[0182] Test items performance Detection Methods Surface drying time / min 100 GB / T1728-2020 Drying time / d 5 GB / T1728-2020 Pencil hardness 5B GB / T6739-2006 Coating gloss / (60°,%) 91 GB / T9754-2007 Water resistance (25℃, 24h) 4. Severe marks GB / T4893.1-2020 Dry heat resistance (70±2℃, 15h) 4. Severe marks GB / T4893.3-2020 Ethanol resistance (50%, 1h) 4. Severe marks GB / T4893.1-2020

[0183] It can be seen from the above table that the bio-based two-component polyurethane coating 6 of this comparative example has longer surface drying and actual drying time than the bio-based two-component polyurethane coating 1 of Example 1, which is not conducive to improving construction efficiency. The paint film pencil hardness, water resistance, dry heat resistance and ethanol resistance are far inferior to those of Example 1.

[0184] Comparative Example 4

[0185] A method for preparing a bio-based hydroxy polyacrylate dispersion 7 comprises the following steps:

[0186] (1) By weight, 16.3 parts of acrylic acid, 12.7 parts of methyl methacrylate, 20 parts of styrene, 8.7 parts of butyl acrylate, 10.7 parts of hydroxyethyl methacrylate, 10.6 parts of isobornyl acrylate, and 1.5 parts of di-tert-amyl peroxide were mixed uniformly to form a mixed solution;

[0187] (2) Add 30 parts of tert-butyl glycidyl carbonate monomer to a four-necked flask equipped with a thermometer, a condenser, a stirring paddle and a constant pressure dropping funnel, mix, stir and heat. When the temperature reaches 145°C, start to drop the mixed solution prepared in step (1) and complete the dropwise addition within 4 hours. After the dropwise addition is completed, stir and keep warm for 30 minutes. Cool down to 80°C, add 15 parts of GreenSoft D special epoxy soybean oil and 4.3 parts of N,N-dimethylcyclohexylamine, stir for 5 minutes, add 150 parts of deionized water and disperse at high speed for 3 minutes. Transfer to an autoclave, pressurize to 2 MPa, heat to 80°C, react for 60 minutes, and determine the epoxy value of the product by the hydrochloric acid-acetone method to be constant at 0.023. The epoxy soybean oil does not undergo polycondensation reaction with the hydroxy acrylate polymer. Cool down to below 40°C, release the pressure, filter and discharge the product to obtain a bio-based hydroxy polyacrylate dispersion 7.

[0188] The bio-based hydroxy polyacrylate dispersion 7 prepared in this example has a bio-based content of 11.6%, a semi-transparent appearance, a pH of 5, a hydroxyl content of 2.8%, a solid content of 46.5%, a viscosity of 1750 cp, an average particle size of 118 nm, and stratification after heat storage at 50°C for 1 month.

[0189] This comparative example is a hydroxy polyacrylate dispersion synthesized by changing the high temperature reaction of Example 1 to 80°C reaction. Its bio-based content, solid content, and appearance are consistent with those of Example 1, but the pH is acidic and the hydroxyl content is low. The reason for the above problems is that the epoxy group of the epoxidized soybean oil does not react with the carboxyl group of the hydroxy polyacrylate polymer at 80°C.

[0190] A two-component polyurethane coating 7, comprising an agent A and an agent B;

[0191] Agent A is composed of the following components in parts by weight:

[0192]

[0193] Agent B includes 17.5 parts of a water-based polyisocyanate curing agent (Bayhydur XP 2487 / 1).

[0194] The molar ratio of NCO in agent B to OH in agent A in the two-component polyurethane coating 1 is 1.8:1.

[0195] The preparation method of agent A of the above-mentioned two-component polyurethane coating is as follows: add the bio-based hydroxy polyacrylate dispersion 7 into a stirring tank at a rotation speed of 700 rpm, premix water, dipropylene glycol butyl ether and dipropylene glycol methyl ether and add them into the stirring tank, add TEGO-800, RM-8W, TEGO-245 and TEA (triethanolamine) in sequence, disperse for 20 minutes, and filter the material.

[0196] During construction, agent B was added to agent A and stirred for 6 minutes to obtain a two-component polyurethane coating 7, whose biobased content was 6.1%.

[0197] The paint film was prepared using two-component polyurethane coating 7 and cured and dried at room temperature for 7 days. The properties of the paint film are shown in Table 7:

[0198] Table 7: Comprehensive properties of two-component polyurethane coating 7

[0199]

[0200]

[0201] It can be seen from the above table that the bio-based two-component polyurethane coating 7 of this comparative example has longer surface drying and actual drying time than the bio-based two-component polyurethane coating 1 of Example 1, which is not conducive to improving construction efficiency. The paint film pencil hardness, coating film gloss, water resistance, dry heat resistance and ethanol resistance are far inferior to those of Example 1.

[0202] It can be seen from Examples 1-3 that the present invention discloses a method for preparing a bio-based hydroxy polyacrylate dispersion. The bio-based hydroxy polyacrylate dispersion prepared by the preparation method has a high solid content, good appearance and good stability; the paint film made of the prepared bio-based water-based two-component polyurethane coating has the advantages of high hardness, high gloss, high transparency, excellent water and chemical resistance, high crosslinking density, scratch resistance, wear resistance and fast drying speed, and can be applied to high-end wood coatings, automotive coatings, metal anti-corrosion coatings and other industrial protective coatings.

[0203] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a bio-based hydroxy polyacrylate dispersion, characterized in that: The raw material components used in the preparation method include acrylic monomers, acrylic ester monomers, vinyl-containing monomers, bio-based chain extenders, initiators, active diluents, neutralizers, and water; The bio-based chain extender is a vegetable oil containing three or more epoxy groups, and the bio-based chain extender is reacted at a temperature above 140° C. to obtain the bio-based hydroxy polyacrylate dispersion; The preparation method comprises the following steps: The acrylic monomer, the acrylate monomer, the vinyl-containing monomer, and the initiator are mixed to form a mixed solution; The active diluent is heated to 135-155° C., then dripped into the mixed solution, stirred, kept warm, then cooled to 70-85° C., the bio-based chain extender, neutralizer, and water are added, dispersed, and then reacted at a temperature above 160° C. for 40-80 minutes to obtain the bio-based hydroxy polyacrylate dispersion; The acrylic acid ester monomers include hydroxy acrylic acid ester monomers and at least one of methyl methacrylate, butyl acrylate, isobornyl acrylate, cyclohexyl methacrylate or benzyl methacrylate; The reactive diluent is a substance containing one epoxy group and no double bond.

2. The preparation method according to claim 1, characterized in that: The acrylic monomer is selected from at least one of acrylic acid or methacrylic acid; the hydroxy acrylate monomer is selected from at least one of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate or hydroxypropyl methacrylate.

3. The preparation method according to claim 1, characterized in that: The vinyl-containing monomer includes styrene; and the bio-based chain extender is selected from at least one of epoxidized soybean oil and epoxidized linseed oil.

4. The preparation method according to claim 1, characterized in that: The following steps are involved: By weight, 10-28 parts of acrylic monomer, 30-58 parts of acrylate monomer, 12-25 parts of vinyl-containing monomer, and 1-3.5 parts of initiator are mixed to form a mixed solution; In parts by mass, 20-40 parts of active diluent are heated to 135-155° C. and then dripped into the mixed solution at constant pressure within 2-5 hours. After dripping, the mixture is stirred and kept warm for 20-40 minutes, cooled to 70-85° C., 8-25 parts of bio-based chain extender and 3.0-5.3 parts of neutralizer are added, stirred for 3-5 minutes, 135-150 parts of water are added and dispersed for 3-5 minutes, transferred to a reactor, pressurized to 2-2.5 MPa, heated to 160-185° C., reacted for 40-85 minutes, and the reaction was stopped after the epoxy value of the product was less than 0.005 determined by the hydrochloric acid-acetone method, cooled to below 40° C., depressurized, filtered and discharged to obtain the bio-based hydroxy polyacrylate dispersion.

5. A bio-based hydroxy polyacrylate dispersion, characterized in that: The bio-based hydroxy polyacrylate dispersion is prepared by the preparation method according to any one of claims 1 to 4, and the solid content of the bio-based hydroxy polyacrylate dispersion is greater than 45% by mass.

6. A two-component polyurethane coating, characterized in that: Includes dose A and dose B; The agent A comprises the bio-based hydroxy polyacrylate dispersion according to claim 5; The B agent includes a water-based polyisocyanate curing agent; The molar ratio of NCO in the B agent to OH in the A agent is 1.0-2.0:

1.

7. The two-component polyurethane coating according to claim 6, characterized in that: The A agent comprises the following components in parts by weight: Bio-based hydroxy polyacrylate dispersion 55-68 parts 28-40 parts water 2-5 parts of film-forming aid Defoamer 0.05-0.5 parts Thickener 0.5-1 part Wetting agent 0.05-0.5 parts Neutralizer 0.2-0.8 parts; The B agent includes 20-30 parts of water-based polyisocyanate curing agent.

8. Use of the two-component polyurethane coating according to claim 6 or 7 in the field of wood, automobile or metal corrosion protection.

Images