Organic-inorganic hybrid water-based acrylic acid modified epoxy ester resin and preparation method thereof

Abstract

The invention relates to the technical field of water-based epoxy ester resin, and particularly discloses organic-inorganic hybrid water-based acrylic acid modified epoxy ester resin and a preparation method thereof in order to solve the problem that hardness and salt spray resistance of an existing epoxy ester resin coating are difficult to consider at the same time. Raw materials of the epoxy resin comprise 25-35 parts of epoxy resin, 22-30 parts of dry vegetable oleic acid or semi-dry vegetable oleic acid, 6-10 parts of a hard monomer, 5-15 parts of an inorganic precursor, 4-6 parts of reflux xylene, 3-5 parts of carboxyl acrylic acid, 0.4-0.6 part of an initiator, 0.05-0.25 part of a catalyst and 20-25 parts of an alcohol ether cosolvent. Specific preparation raw materials and production process conditions are adopted to construct the organic-inorganic hybrid water-based acrylic acid modified epoxy ester resin with a stable and uniform structure and a composite network structure, and the epoxy ester resin not only has remarkable hardness, but also has good water resistance, salt fog resistance and drying speed; the epoxy ester resin coating can be suitable for more application scenes.

Description

Technical Field

[0001] This invention relates to the field of waterborne epoxy ester resin technology, and more specifically, to an organic-inorganic hybrid waterborne acrylic modified epoxy ester resin and its preparation method. Background Technology

[0002] Epoxy ester resins are commonly found in solvent-based coatings produced by the esterification reaction of epoxy resins with fatty acids from vegetable oils, with epoxy esters as the main film-forming substance. They are widely used in metal primers for automobiles, tractors, etc., exhibiting strong adhesion to iron and aluminum metals and producing tough coatings. However, traditional epoxy ester resins suffer from problems such as low hardness, poor water resistance, low salt spray resistance, and slow drying, which seriously affect their application in many fields and scenarios, especially making it difficult to meet the performance requirements of automotive parts coatings.

[0003] To improve the performance of epoxy ester resins, techniques for modifying epoxy ester resins using organic or inorganic materials have been proposed. For example, patent CN111019281A discloses an acrylate-epoxy resin hybrid emulsion, its preparation method, uses, and artificial colored sand using the same. The acrylate-epoxy resin hybrid emulsion comprises acrylic resin, epoxy resin, and an emulsifier. The epoxy resin is dispersed within a network of the acrylic resin. The acrylic resin is a polymerization product of acrylate monomers. By blending different acrylates, an acrylic resin with good hardness is synthesized. For example, patent CN108570132A discloses a hybrid emulsion of epoxy ester resin aqueous dispersion and acrylic resin, comprising 5-90 parts of epoxy ester resin aqueous dispersion, 1-50 parts of acrylic monomer, 0-7 parts of emulsifier, 0-2 parts of pH adjuster, 0.05-7 parts of initiator and 0-60 parts of water. The epoxy ester resin and acrylic resin are hybridized to obtain a hybrid emulsion that has the advantages of both resins, and features good aging resistance and salt spray resistance.

[0004] However, even with the combination of multiple raw materials, existing epoxy ester resin coatings still suffer from the problem of not being able to simultaneously achieve both high hardness and salt spray resistance. Therefore, there is an urgent need for an epoxy ester resin with superior overall performance. Summary of the Invention

[0005] The purpose of this invention is to solve the problem that existing epoxy ester resin coatings generally have difficulty in achieving both hardness and salt spray resistance.

[0006] This invention is achieved through the following technical solution: This invention provides an organic-inorganic hybrid waterborne acrylic modified epoxy ester resin, comprising, by weight, the following raw materials: 25-35 parts epoxy resin, 22-30 parts drying or semi-drying vegetable oleic acid, 6-10 parts hard monomer, 5-15 parts inorganic precursor, 4-6 parts reflux xylene, 3-5 parts carboxylic acid, 0.4-0.6 parts initiator, 0.05-0.25 parts catalyst, and 20-25 parts alcohol ether cosolvent.

[0007] Preferably, the dry or semi-dry vegetable oleic acid includes a mixture of ricinoleic acid with one or more of the following: soybean oil fatty acids, rice bran oleic acid, tall oil, sunflower oil fatty acids, cottonseed oil fatty acids, and linolenic acid.

[0008] Preferably, the hard monomer is selected from one or more mixtures of styrene, methyl methacrylate, etc., and is compounded with glycidyl methacrylate or vinyltriethoxysilane.

[0009] Preferably, the inorganic precursor comprises core-shell nano-silica and silica-containing sol in a mass ratio of 1:1.5-3.

[0010] Preferably, the preparation method of the core-shell type nano-silica includes the following steps: A1. By mass, mix and stir 40-50 parts of anhydrous ethanol, 8-12 parts of deionized water, and 0.5-1 parts of surfactant until completely dissolved. Then add hydrochloric acid dropwise to adjust the pH of the system to 2-3. Heat to 40-50℃ and add 15-20 parts of tetraethyl orthosilicate. Keep warm for 2-3 hours to form a dispersion containing core material nano-SiO2 with a particle size of 20-30nm. A2. The dispersion of core-containing nano-SiO2 is heated to 60-70℃, and a silane coupling agent is added dropwise. The mixture is kept at this temperature for 3-4 hours to form a 5-10 nm thick organosilane shell on the surface of the core-containing nano-SiO2, thus obtaining core-shell nano-silica. The shell is then centrifuged, washed, dispersed in anhydrous ethanol, and stored for later use.

[0011] The present invention also provides a method for preparing the above-mentioned organic-inorganic hybrid waterborne acrylic modified epoxy ester resin, comprising the following steps: S1 Preparation of organic phase: The epoxy resin, dry or semi-dry vegetable oleic acid, xylene, and catalyst are added to the reactor according to the specified amount, heated for reflux esterification, and then the reaction is continued under vacuum to obtain epoxy ester resin prepolymer. Vacuuming is then stopped. Depressurize and cool the reactor to 130-140℃; separately take hard monomer, carboxyacrylic acid, and initiator, mix them, add them to the reactor, and keep the temperature at 130-140℃ for reaction; then add initiator and alcohol ether cosolvent to carry out elimination reaction to obtain waterborne acrylic modified epoxy ester resin prepolymer; S2 Inorganic phase hybridization treatment: Take tetraethyl orthosilicate and anhydrous ethanol, mix them, add hydrochloric acid dropwise, adjust the pH of the reaction system to 2-4, stir the reaction for 0.5-2 hours to form a silica sol, then add core-shell nano silica, stir well, and obtain inorganic phase material; Inorganic phase material is added dropwise to waterborne acrylic modified epoxy ester resin prepolymer, heated to 80-85℃, and stirred to react; then silane coupling agent is added, and stirred to react to obtain the organic-inorganic hybrid waterborne acrylic modified epoxy ester resin.

[0012] Preferably, in step S1, the temperature is raised to 180-220°C for reflux esterification; After reflux for 2-3 hours, start sampling to measure the acid value, calculated as solid content. When the acid value is ≤8mgKOH / g, start vacuuming. After vacuuming for 1 hour, samples are taken to measure the acid value. Based on the solid content, when the acid value is ≤5mgKOH / g, the epoxy ester resin prepolymer is obtained.

[0013] Preferably, in step S1, the initiator is added in two parts, with the first addition being 80-98 wt% of the total mass of the initiator, and the remaining initiator being added in the second addition.

[0014] Further, in step S1, when the remaining initiator is added for the last time, the remaining initiator is mixed with an alcohol ether co-solvent until it is diluted 5-15 times to obtain the initiator preparation solution. First, take an initiator solution with a volume fraction of 30-70% and add it dropwise into the reactor at a uniform rate over 30-60 minutes for one elimination, and keep it warm for 0.5-2 hours. Then, add the remaining initiator solution dropwise into the reactor at a uniform rate over 30-60 minutes for a second elimination, and then keep it warm for 0.5-2 hours. Then add the remaining alcohol ether co-solvent, dilute and stir well to obtain water-based acrylic modified epoxy ester resin prepolymer.

[0015] Preferably, in step S2, the inorganic phase material is added dropwise to the waterborne acrylic modified epoxy resin prepolymer at a uniform rate, and the total dropwise addition time is 1-5 hours.

[0016] The technical solution of the present invention has the following beneficial effects: This invention employs specific raw materials and production process conditions to embed inorganic phases and acrylic copolymer units into waterborne epoxy ester resin segments, forming chemically bonded organic-inorganic hybrid segments with specific spatial structures. The main chain consists of alternating arrangements of epoxy ester resin and acrylic copolymer units, while SiO2 is chemically bonded to the main chain or cross-linked network, forming an epoxy ester resin-acrylic acid-SiO2 ternary composite structure. This organic-inorganic hybrid waterborne acrylic-modified epoxy ester resin exhibits significant hardness, excellent water resistance, salt spray resistance, and fast drying speed, broadening the application scenarios of waterborne epoxy ester resins, especially in anti-corrosion and anti-rust paints for automotive parts. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, they are performed according to conventional conditions or conditions recommended by the manufacturer; where the manufacturers of the instruments, equipment, reagents, or raw materials used are not specified, they are all conventional products that can be purchased commercially.

[0018] This invention provides an organic-inorganic hybrid waterborne acrylic modified epoxy resin, comprising an organic phase and an inorganic phase.

[0019] The organic phase mainly includes waterborne acrylic modified epoxy ester resin prepolymer, which is prepared by epoxy resin, catalyst and fatty acid esterification reaction to obtain epoxy ester prepolymer, and then graft copolymerized with carboxylic acid, hard monomer and initiator to obtain waterborne acrylic modified epoxy ester resin prepolymer.

[0020] The inorganic phase mainly includes silica sol, which is introduced in situ via a sol-gel method and undergoes a condensation reaction with the organic phase to form an interpenetrating network structure containing Si-O-Si bonds. The siloxane bonds with the hydroxyl / carboxyl groups in the resin, ultimately yielding an organic-inorganic hybrid waterborne acrylic modified epoxy resin. This achieves complete molecular bonding between the inorganic and organic phases, significantly improving salt spray resistance and hardness.

[0021] Specifically, by mass fraction, the raw materials for preparing the above-mentioned organic-inorganic hybrid waterborne acrylic modified epoxy ester resin include: 25-35 parts epoxy resin, 22-30 parts drying or semi-drying vegetable oleic acid, 6-10 parts hard monomer, 5-15 parts inorganic precursor, 4-6 parts reflux xylene, 3-5 parts carboxylic acid, 0.4-0.6 parts initiator, 0.05-0.25 parts catalyst, and 20-25 parts alcohol ether co-solvent.

[0022] The epoxy resin is a bisphenol A type epoxy resin, specifically selected from one or more mixtures of E-12, E-20, E-44, E-51, etc.

[0023] The drying or semi-drying vegetable oleic acid is selected from one or more mixtures of soybean oil fatty acids, rice bran oleic acid, tall oil, sunflower oil fatty acids, cottonseed oil fatty acids, linolenic acid, ricinoleic acid, etc. Those skilled in the art may choose hydroxyl-containing ricinoleic acid mixed with other vegetable oleic acids as a raw material. The hydroxyl groups in ricinoleic acid can react with inorganic silanols, and the long carbon chain of ricinoleic acid can alleviate the brittleness caused by excessive resin rigidity, preventing the paint film from cracking after hardness is increased, thus balancing high hardness and impact resistance.

[0024] The hard monomers are selected from one or more mixtures of styrene, methyl methacrylate, etc., and are compounded with glycidyl methacrylate or vinyltriethoxysilane, with the mass of glycidyl methacrylate or vinyltriethoxysilane accounting for 5-8 wt% of the total mass of the hard monomers. One end of the compounded monomer contains a double bond, which can copolymerize with acrylic acid to integrate into the organic phase, while the other end contains an epoxy / siloxane group, which can react with the inorganic phase to form a molecular bridge, thereby avoiding the aggregation of the inorganic phase and improving the synergy between hardness and salt spray resistance.

[0025] The inorganic precursor comprises core-shell nano-silica and silica sol in a mass ratio of 1:1.5-3, with the core-shell nano-silica having a particle size of 20-50 nm. The core-shell nano-silica provides rigid support through its core, enhancing hardness, and its shell bonds with the hydroxyl / carboxyl groups in the resin, reducing interfacial defects and extending salt spray resistance.

[0026] Core-shell nano-silica can be prepared using the following method: (1) Preparation of core material nano-SiO2: Add 40-50 parts by mass of anhydrous ethanol, 8-12 parts by mass of deionized water, and 0.5-1 parts by mass of surfactant to a three-necked flask and stir for 10-15 minutes until completely dissolved. Then add 3-5 parts by mass of 0.1 mol / L hydrochloric acid solution to adjust the pH of the system to 2-3. Heat the system to 40-50℃ and slowly add 15-20 parts by mass of tetraethyl orthosilicate at a dropping rate of 1-2 drops / s. After the addition is complete, keep the system warm and stir for 2-3 hours to form a core material nano-SiO2 dispersion with a particle size of 20-30 nm.

[0027] (2) Shell material coated with organosilane: The above-mentioned core material nano-SiO2 dispersion was heated to 60-70℃, and 5-8 parts of γ-glycidyl etheroxypropyltrimethoxysilane KH-560 were slowly added dropwise over a period of 1-1.5 h. After the addition was completed, the mixture was kept warm and stirred for 3-4 h to allow the siloxane group of KH-560 to undergo a condensation reaction with the hydroxyl group on the surface of the core material nano-SiO2, forming an organosilane shell layer 5-10 nm thick on the core surface. After the reaction was completed, the mixture was centrifuged at 8000-10000 r / min for 15-20 min and washed 2-3 times with anhydrous ethanol to obtain core-shell nano-silica, which was then dispersed in anhydrous ethanol to obtain a core-shell nano-SiO2 dispersion.

[0028] Carboxyacrylic acid is selected from one or more mixtures of acrylic acid, methacrylic acid, itaconic acid, and butenoic acid.

[0029] The initiator is selected from one or more mixtures of benzoyl peroxide, tert-butyl peroxide, azobisisobutyronitrile, and dimethyl azobisisobutyronitrile.

[0030] The catalyst is selected from one or more of zinc oxide, lead oxide, dibutyltin dilaurate, dibutyltin oxide, etc.

[0031] This invention also provides a method for preparing the above-mentioned organic-inorganic hybrid waterborne acrylic modified epoxy ester resin, specifically including the following steps: (1) Preparation of organic phase: Add epoxy resin, dry or semi-dry vegetable oleic acid, xylene, and catalyst to the reactor according to the specified amounts, heat to 180-220℃, and perform reflux esterification. After reflux for 2-3 hours, start sampling to measure the acid value. When the acid value is ≤8mgKOH / g (based on solid content), start vacuuming and remove the refluxed xylene. After vacuuming for 1 hour, start sampling to measure the acid value again. When the acid value is ≤5mgKOH / g (based on solid content), the epoxy ester resin prepolymer is obtained, and stop vacuuming.

[0032] Take a hard monomer, carboxylic acid, and a portion of the initiator (approximately 80-98 wt% of the total initiator) and mix them. Depressurize and cool the reactor to 130-140°C, and then uniformly drop the mixture into the epoxy ester resin prepolymer reactor. The total dropping time is 3-4 hours. After the dropping is completed, keep the temperature at 130-140°C for 0.5-2 hours to carry out the graft copolymerization reaction.

[0033] Take the remaining initiator and dilute it about 5-15 times with an alcohol ether co-solvent to obtain an initiator preparation solution. Take an initiator preparation solution with a volume fraction of 30-70% and add it dropwise to the reactor at a uniform rate over 30-60 minutes for the first elimination, and keep it warm for 0.5-2 hours. Then add the remaining initiator preparation solution dropwise to the reactor at a uniform rate over 30-60 minutes for the second elimination, and keep it warm for another 0.5-2 hours. Add the remaining alcohol ether co-solvent, dilute and stir well to obtain an aqueous acrylic modified epoxy ester resin prepolymer.

[0034] (2) Inorganic phase hybridization treatment: Tetraethyl orthosilicate and anhydrous ethanol were mixed at a mass ratio of 1:3-5, and 0.1M hydrochloric acid solution was added dropwise. Catalytic hydrolysis was carried out under the condition that the pH value of the reaction system was 2-4. The reaction was stirred for 0.5-2 hours to form a transparent silica-containing sol. Then, core-shell nano-silica was mixed with the silica-containing sol at a mass ratio of 1:1.5-3 and stirred at 1000-1500 rpm for 0.5-2 hours to obtain the inorganic phase material.

[0035] The silica sol is added dropwise at a uniform rate to the waterborne acrylic-modified epoxy ester resin prepolymer for a total dropping time of 1-5 hours. The mixture is stirred at 80-85℃ for 1-5 hours to carry out a condensation reaction, forming molecular-level bonds and gradually achieving silanol bonding. The hydroxyl groups on the silanol directly react with the carboxyl groups on the waterborne acrylic-modified epoxy ester resin prepolymer, introducing Si into the system and forming an interpenetrating network structure containing a large number of Si-O-Si bonds. Then, a silane coupling agent is added and reacted at 70-80℃ for 0.5-3 hours to bond the siloxane with the hydroxyl / carboxyl groups in the resin, resulting in an organic-inorganic hybrid waterborne acrylic-modified epoxy ester resin with superior adhesion, salt spray resistance, and water resistance.

[0036] Example 1 The organic-inorganic hybrid waterborne acrylic modified epoxy resin of this embodiment, by mass parts, includes 25 parts of E-12 epoxy resin, 22 parts of soybean oil acid, 1 part of ricinoleic acid, 9.3 parts of styrene, 0.7 parts of glycidyl methacrylate, 10 parts of inorganic precursor, 4 parts of xylene, 5 parts of methacrylic acid, 0.6 parts of benzoyl peroxide, 0.25 parts of zinc oxide, and 22.15 parts of propylene glycol methyl ether.

[0037] Step 2: Add soybean oil acid, ricinoleic acid, E-12 epoxy resin, zinc oxide, and xylene to the reactor according to the specified amounts, heat to 200±5℃, and reflux esterification. After reflux for 2 hours, start sampling to measure the acid value. Based on the solid content, when the acid value is ≤8mgKOH / g, start vacuuming and remove the refluxed xylene. After vacuuming for 1 hour, start sampling to measure the acid value. When the acid value is ≤5mgKOH / g, the epoxy ester resin prepolymer is obtained, and vacuuming is stopped.

[0038] Separately, take methacrylic acid, styrene, glycidyl methacrylate, and 0.5 parts of benzoyl peroxide and mix them; depressurize the reactor and cool it to 135±5℃, and then uniformly add the above mixture to the epoxy ester resin prepolymer reactor. The total addition time is 3.5h. After the addition is completed, keep it at the temperature for 1h.

[0039] Take the remaining 0.1 part of benzoyl peroxide and dilute it with 1 part of propylene glycol methyl ether to obtain the initiator preparation solution. Take half of the initiator preparation solution and add it dropwise to the reaction vessel at a uniform rate over about 40 minutes for the first elimination. Keep it at 130±5℃ for 1 hour. Then add the remaining half of the initiator preparation solution dropwise to the reaction vessel at a uniform rate over about 40 minutes for the second elimination. Keep it at 130±5℃ for another 1 hour. Add the remaining alcohol ether co-solvent, dilute and stir well to obtain the water-based acrylic modified epoxy ester resin prepolymer.

[0040] Step 3: Take tetraethyl orthosilicate and anhydrous ethanol at a mass ratio of 1:4, mix them, add 0.1M hydrochloric acid solution dropwise, control the pH of the reaction system to 3, carry out catalytic hydrolysis, stir the reaction for 1 hour to form a transparent silica sol, then mix core-shell nano-silica with silica sol at a mass ratio of 1:2, stir at 1200 rpm for 1 hour to obtain inorganic phase material.

[0041] The inorganic phase material was added dropwise at a uniform rate to the waterborne acrylic modified epoxy ester resin prepolymer for a total dropwise time of 3 hours, and stirred at 80°C for 2 hours. Then, γ-glycidyl etheroxypropyltrimethoxysilane was added, and the mixture was reacted at 75°C for 1 hour to obtain the organic-inorganic hybrid waterborne acrylic modified epoxy ester resin.

[0042] Example 2 The difference between this embodiment and Embodiment 1 is that, by mass parts, the raw materials include 30 parts of E-12 epoxy resin, 20 parts of soybean oil, 5 parts of ricinoleic acid, 6.4 parts of styrene, 0.1 parts of glycidyl methacrylate, 8.5 parts of inorganic precursor, 4 parts of xylene, 3 parts of methacrylic acid, 0.6 parts of benzoyl peroxide, 0.25 parts of zinc oxide, and 22.15 parts of propylene glycol methyl ether.

[0043] Example 3 The difference between this embodiment and Embodiment 1 is that the mass ratio of core-shell nano-silica to silica-containing sol in the inorganic phase material is 1:3.

[0044] Example 4 The difference between this embodiment and Embodiment 1 is as follows: In step two, after stopping the vacuuming, methacrylic acid, styrene, glycidyl methacrylate, and benzoyl peroxide are taken separately and mixed; the pressure of the reactor is released and the temperature is lowered to 135±5℃, and then the above mixture is uniformly added dropwise to the epoxy ester resin prepolymer reactor for a total dropwise time of 3.5h. After the dropwise addition is completed, the temperature is maintained for 1h; then propylene glycol methyl ether is added for dilution, and the temperature is maintained at 130±5℃ for 3.5h. After dilution and stirring, waterborne acrylic acid modified epoxy ester resin prepolymer is obtained.

[0045] Example 5 The difference between this embodiment and Example 1 is that: the inorganic phase material is added dropwise at a uniform rate to the waterborne acrylic modified epoxy ester resin prepolymer for a total dropwise time of 1 hour, and stirred at 80°C for 5 hours; then γ-glycidyl etheroxypropyltrimethoxysilane is added, and the mixture is reacted at 75°C for 1 hour to obtain an organic-inorganic hybrid waterborne acrylic modified epoxy ester resin.

[0046] Comparative Example 1 The difference between this comparative example and Example 1 is that, by mass parts, the raw materials include 25 parts of E-12 epoxy resin, 23 parts of soybean oil acid, 10 parts of styrene, 10 parts of nano silica sol, 4 parts of xylene, 5 parts of methacrylic acid, 0.6 parts of benzoyl peroxide, 0.25 parts of zinc oxide, and 22.15 parts of propylene glycol methyl ether. The above raw materials are placed in a reaction vessel, heated to 220°C, and reacted for 2 hours to obtain the modified epoxy ester resin.

[0047] Comparative Example 2 The difference between this comparative example and Example 1 is that, by mass parts, the raw materials include 25 parts of E-12 epoxy resin, 23 parts of soybean oil acid, 10 parts of styrene, 10 parts of nano-silica powder with a particle size of 20 nm, 4 parts of xylene, 5 parts of methacrylic acid, 0.6 parts of benzoyl peroxide, 0.25 parts of zinc oxide, and 22.15 parts of propylene glycol methyl ether, and the preparation method is the same.

[0048] Test case Samples: Examples 1-5, Comparative Examples 1-2 Several portions of the above samples were taken and mixed with a fatty amine curing agent at a ratio of 10:1. The mixtures were then sprayed onto the surface of a 150mm × 70mm × 0.8mm cold-rolled steel sheet (previously treated for rust and oil removal) to form a dry film thickness of approximately 40μm. The mixtures were cured for 7 days at 25℃ and 60% relative humidity to obtain the test samples. Various properties of the different test samples were measured according to the test methods. The results are summarized in Table 1 below. Table 1. Test results of different performance of different samples

[0049] The results of the above experiments show that: (1) Hardness comparison: The pencils of Examples 1-5 all reached a hardness of 3H-4H, which was significantly higher than that of Comparative Examples 1-2. Among them, Examples 1, 3, and 5 used inorganic precursors composed of core-shell nano-silica and silica sol, and glycidyl methacrylate was added to the hard monomer, resulting in more uniform dispersion of the inorganic phase and stronger bonding with the organic phase interface, thus increasing the hardness to 4H. Examples 2 and 4 had a slightly lower hardness of 3H due to the increased amount of ricinoleic acid or the adjustment of the initiator elimination process, but were still significantly better than the comparative examples.

[0050] (2) Salt spray resistance comparison: The salt spray resistance time of Examples 1-5 was all above 680h, with the highest reaching 750h, while the traditional silica sol of Comparative Example 1 was only 450h, and the nano silica powder of Comparative Example 2 was only 380h. This is because the organic shell of the core-shell nano silica in the examples is bonded to the hydroxyl / carboxyl groups of the resin to form a dense Si-O-Si interpenetrating network, which blocks salt spray erosion; while the traditional silica sol in Comparative Example 1 is prone to agglomeration, and the nano powder in Comparative Example 2 has poor dispersibility, and neither can form an effective protective barrier.

[0051] (3) Comparison of water resistance and adhesion: After 240h of water resistance, the adhesion of Examples 1-3 and 5 remained at level 1. In Example 4, due to the lack of step-by-step initiator elimination process, the resin crosslinking degree was slightly lower and the adhesion dropped to level 2. In Comparative Examples 1-2, due to weak interfacial bonding, the bonding force between the coating and the substrate decreased after water resistance, and the adhesion was level 3-4 respectively. In addition, Comparative Example 2 showed obvious whitening.

[0052] (4) Comparison of drying time: The surface drying time of Examples 1-5 was 2.5-3.2h and the actual drying time was 22-26h, which was shorter than that of Comparative Examples 1-2. This is due to the accelerated cross-linking of ricinoleic acid by hydroxyl groups in the examples and the promotion of organic-inorganic reaction by glycidyl methacrylate, which shortened the curing cycle.

[0053] (5) Impact resistance comparison: Examples 1-5 all passed the 1kg×50cm impact test, while Comparative Examples 1-2 showed cracks or peeling of varying degrees. This is because the long carbon chain of ricinoleic acid in the examples relieved the rigidity of the resin, and the shell of the core-shell nano-silica buffered the impact stress, avoiding the coating from becoming brittle; in the comparative examples, the resin was too rigid and had no flexible chain segment adjustment, resulting in poor impact resistance.

[0054] In summary, this invention improves and combines various raw materials such as inorganic precursors, and through specific process conditions, enables them to undergo directional chemical modification reactions, effectively solving the problem of difficulty in achieving both hardness and salt spray resistance in traditional epoxy ester resin coatings. Furthermore, when this epoxy ester resin is used as a coating, it also possesses high hardness, excellent salt spray resistance, and good impact resistance.

[0055] The above are merely preferred embodiments of the present invention and are not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An organic-inorganic hybrid aqueous acryl-modified epoxy ester resin, characterized by, The raw materials include, by mass fraction, 25-35 parts of epoxy resin, 22-30 parts of dry vegetable oil acid or semi-dry vegetable oil acid, 6-10 parts of hard monomer, 5-15 parts of inorganic precursor, 4-6 parts of refluxing xylene, 3-5 parts of carboxyl acrylic acid, 0.4-0.6 parts of initiator, 0.05-0.25 parts of catalyst and 20-25 parts of alcohol ether cosolvent.

2. The organic-inorganic hybrid water-based acryl-modified epoxy ester resin according to claim 1, characterized by, The dry vegetable oil acid or semi-dry vegetable oil acid includes a mixture of castor oil acid and one or more of soybean oil fatty acid, rice bran oil acid, tall oil acid, sunflower oil acid, cotton oil fatty acid and linseed oil fatty acid.

3. The organic-inorganic hybrid water-based acryl-modified epoxy ester resin according to claim 1, characterized by, The hard monomer is selected from one or more of styrene, methyl methacrylate and the like, and is compounded with glycidyl methacrylate or vinyl triethoxysilane.

4. The organic-inorganic hybrid water-based acryl-modified epoxy ester resin according to claim 1, characterized by, The inorganic precursor includes core-shell type nano-silica and silica sol with a mass ratio of 1:1.5-3.

5. The organic-inorganic hybrid water-based acryl-modified epoxy ester resin according to claim 1, characterized by, The preparation method of the core-shell type nano-silica includes the following steps: A1, by mass fraction, 40-50 parts of anhydrous ethanol, 8-12 parts of deionized water, 0.5-1 parts of surfactant are mixed and stirred until completely dissolved, then hydrochloric acid is added dropwise to adjust the pH of the system to 2-3; Heat to 40-50℃, add 15-20 parts of tetraethyl orthosilicate dropwise, and keep warm for 2-3h to form a dispersion liquid containing core material nano-SiO2 with a particle size of 20-30nm; A2, the dispersion liquid containing core material nano-SiO2 is heated to 60-70℃, silane coupling agent is added dropwise, and kept warm for 3-4h to form a 5-10nm thick organic silane shell material on the surface of the core material nano-SiO2 to obtain core-shell type nano-silica, which is then centrifuged, washed, dispersed in anhydrous ethanol and stored for use.

6. A method for preparing the organic-inorganic hybrid aqueous acryl-modified epoxy ester resin according to any one of claims 1 to 5, characterized by, The preparation method includes the following steps: S1, preparation of organic phase: The epoxy resin, dry vegetable oil acid or semi-dry vegetable oil acid, xylene and catalyst are added to the reaction kettle in a certain amount, heated and refluxed for esterification, then vacuum is applied for continuous reaction to obtain an epoxy ester resin prepolymer, and the vacuum is stopped; The reaction kettle is depressurized and cooled to 130-140℃; the hard monomer, carboxyl acrylic acid and initiator are mixed and added to the reaction kettle, and kept warm at 130-140℃ for reaction; then initiator and alcohol ether cosolvent are added for elimination reaction to obtain a water-based acrylic modified epoxy ester resin prepolymer; S2, inorganic phase hybridization treatment: Take tetraethyl orthosilicate and anhydrous ethanol, mix, add hydrochloric acid dropwise to control the pH value of the reaction system to 2-4, stir for 0.5-2h to form a silica sol, then add core-shell type nano-silica and stir evenly to obtain inorganic phase material; The inorganic phase material is added dropwise to the water-based acrylic modified epoxy ester resin prepolymer, heated to 80-85℃ and stirred for reaction; then silane coupling agent is added and stirred for reaction to obtain the organic-inorganic hybrid water-based acrylic modified epoxy ester resin.

7. The method for preparing the organic-inorganic hybrid waterborne acrylic modified epoxy ester resin according to claim 6, characterized in that, In step S1, heat to 180-220℃ for reflux esterification; After refluxing for 2-3h, start sampling to measure the acid value; when the acid value is ≤8mgKOH / g, start vacuuming; After vacuumizing for 1 hour, sample is taken to measure acid value, and when the acid value is ≤5 mgKOH / g, the epoxy ester resin prepolymer is obtained.

8. The method for preparing the organic-inorganic hybrid waterborne acrylic modified epoxy ester resin according to claim 6, characterized in that, In step S1, the initiator is added twice, and the first addition amount is 80-98 wt% of the total mass of the initiator, and the remaining amount of the initiator is added in the second time.

9. The method for preparing the organic-inorganic hybrid waterborne acrylic modified epoxy ester resin according to claim 8, characterized in that, In step S1, when the remaining amount of the initiator is added, the remaining amount of the initiator is mixed with the alcohol-ether cosolvent until it is diluted by 5-15 times to obtain an initiator preparation solution. First, add the initiator preparation solution with a volume fraction of 30-70% to the reaction kettle at a uniform speed within 30-60 min to perform a first elimination, and keep warm for 0.5-2 h. Then, add the remaining initiator preparation solution to the reaction kettle at a uniform speed within 30-60 min to perform a second elimination, and keep warm for another 0.5-2 h. Then, add the remaining alcohol-ether cosolvent, stir well, and obtain the water-based acrylic modified epoxy ester resin prepolymer.

10. The method for preparing the organic-inorganic hybrid waterborne acrylic modified epoxy ester resin according to claim 6, characterized in that, In step S2, the inorganic phase material is added to the water-based acrylic modified epoxy ester resin prepolymer at a uniform speed, and the total dropping time is 1-5 h.

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