Aqueous hydroxyl acrylate resin, preparation method thereof and aqueous coating for rail transit

Abstract

The application provides a preparation method of an aqueous hydroxyl acrylic resin, comprising the following steps: A) mixing a reactive solvent and a core layer mixed solution, and heating to react, to obtain a core layer; B) mixing an active POSS oligomer and the core layer, and reacting, to obtain an intermediate layer; C) mixing the intermediate layer, a reactive solvent and a shell layer mixed solution, and heating to react, to obtain a three-layer structure material; and D) mixing the three-layer structure material with an initiator, a neutralizing agent and water, and dispersing, to obtain the product. The three-layer structure is provided, the active oligomer OvPOSS is used as the intermediate layer, the hydroxyl content of the hydroxyl acrylic resin is increased, the molecular weight and the compactness of the paint film are increased, the performance of the paint film after curing is more excellent, and the paint film has good hydrophobicity and wear resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of materials, in particular to a water-based hydroxyl acrylic resin, a preparation method thereof and a water-based coating for rail transit. BACKGROUND

[0002] At present, the solvent-based coating used on urban vehicles produces a large amount of VOC in the coating process, resulting in a poor working environment and affecting the surrounding environment. Water-based coating is a coating using water as a solvent or dispersion medium, which does not emit harmful substances and is the trend of rail transit vehicles.

[0003] However, there are still some problems in the construction process of water-based coating for rail transit: 1. The temperature and relative humidity requirements for water-based coating construction are relatively harsh, and air conditioning needs to be added to adjust the temperature and humidity, increasing energy consumption; 2. The volatilization of water is greatly affected by the environment, and low temperature and high humidity seriously affect the drying speed of the paint film; 3. The volatilization rate of water is slow, and less volatilization occurs during spraying, which is prone to sagging.

[0004] The application pain points of the water-based hydroxypropyl resin in the prior art are the balance relationship of solid content, viscosity, molecular weight and hydroxyl value. Therefore, it is necessary to develop a resin with high molecular weight, high hydroxyl value, high solid content and suitable construction viscosity. SUMMARY

[0005] Therefore, the technical problem to be solved by the present application is to provide a preparation method of a water-based hydroxyl acrylic resin. The water-based hydroxyl acrylic resin prepared by the present application has good hydroxyl content and solid content.

[0006] The present application provides a preparation method of a water-based hydroxyl acrylic resin, comprising the following steps:

[0007] A) mixing and heating the reaction-type solvent and the core layer mixed solution to obtain a core layer;

[0008] B) mixing and reacting the active POSS oligomer and the core layer to obtain an intermediate layer;

[0009] C) mixing and heating the intermediate layer, the reaction-type solvent and the shell layer mixed solution to obtain a three-layer structure material;

[0010] D) mixing and dispersing the three-layer structure material with the initiator, the neutralizing agent and water, and obtaining the product.

[0011] Preferably, the core layer mixture of step A) comprises BA, MMA, HEA, MAA, di-t-butyl peroxide, dodecyl mercaptan and glycidyl t-butyl carbonate; the mass ratio of the BA, MMA, HEA, MAA, di-t-butyl peroxide, dodecyl mercaptan and glycidyl t-butyl carbonate is 0-25:0-20:5-40:2-10:0.2-3:0.1-2:0-15.

[0012] Preferably, the step A) is specifically:

[0013] The reactive solvent and part of the core layer mixture are mixed, after 10-60 min of reaction, the remaining part of the core layer mixture is added dropwise, after the dropwise addition is completed, the temperature is kept for 2-4 h; the reaction temperature is 90-150 ℃; the dropwise addition time is 2-4 h.

[0014] Preferably, the mass ratio of the part of the core layer mixture and the remaining part of the core layer mixture is 4:96.

[0015] The reactive solvent comprises glycidyl t-butyl carbonate.

[0016] Preferably, the reaction time of step B) is 30 min-2 h.

[0017] The preparation method of the active POSS oligomer is specifically: taking vinyl triethoxysilane as a raw material, hydrochloric acid as a catalyst, and reacting, to obtain OvPOSS.

[0018] OvPOSS is dissolved in a mixture of butyl acrylate and methyl methacrylate, a solvent is added, and then an initiator is added dropwise to start polymerization, to obtain an active POSS oligomer.

[0019] Preferably, the shell layer mixture of step C) comprises BA, MMA, HEA, MAA, di-t-butyl peroxide, dodecyl mercaptan and glycidyl t-butyl carbonate; the mass ratio of the BA, MMA, HEA, MAA, di-t-butyl peroxide, dodecyl mercaptan and glycidyl t-butyl carbonate is 0-15:0-80:0-10:0.5-5:0.2-3:0-2:0-10.

[0020] Preferably, the step C) is specifically:

[0021] The reactive solvent and part of the core layer mixture are mixed, after 10-60 min of reaction, the remaining part of the core layer mixture is added dropwise, after the dropwise addition is completed, the temperature is kept for 2-4 h; the reaction temperature is 90-150 ℃; the dropwise addition time is 2-4 h; the mass ratio of the part of the core layer mixture and the remaining part of the core layer mixture is 4:96.

[0022] The reactive solvent comprises glycidyl t-butyl carbonate.

[0023] Preferably, step D) specifically is:

[0024] After the three-layer structure material is mixed with the initiator, it is kept warm for 3-6h, and then cooled to 50-90℃, a neutralizing agent is added and neutralized for 30-60min; cooled to 20-80℃, water is added, mixed, dispersed, and obtained;

[0025] The initiator includes di-t-butyl peroxide; the initiator is added in an amount of 0.01-1wt% of the three-layer structure;

[0026] The neutralizing agent includes triethylamine; the amount of the neutralizing agent is determined according to the amount of MAA used, which is 0.8-1.5 times the molar amount of carboxyl in MAA;

[0027] The dispersion is high-speed stirring dispersion for 30-60min.

[0028] The present application provides a water-based hydroxyl acrylic resin prepared by the preparation method of any one of the above technical solutions.

[0029] The present application provides a water-based paint for rail transit, which comprises the water-based hydroxyl acrylic resin of the above technical solution.

[0030] Compared with the prior art, the present application provides a preparation method of a water-based hydroxyl acrylic resin, which comprises the following steps: A) mixing a reactive solvent and a core layer mixed solution, heating and reacting to obtain a core layer; B) mixing an active POSS oligomer and the core layer, and reacting to obtain an intermediate layer; C) mixing the intermediate layer, a reactive solvent and a shell layer mixed solution, heating and reacting to obtain a three-layer structure material; D) mixing the three-layer structure material with an initiator, a neutralizing agent and water, and dispersing, and obtaining. The present application can improve the hydroxyl content of the hydroxyl acrylic resin, increase the molecular weight and the compactness of the paint film by setting the above three-layer structure and using the OvPOSS active oligomer as the intermediate layer, so that the performance of the paint film after curing is more excellent, and the paint film has good hydrophobicity and wear resistance. DETAILED DESCRIPTION

[0031] The present application provides a water-based hydroxyl acrylic resin, a preparation method thereof and a water-based paint for rail transit. Those skilled in the art can refer to the content herein and appropriately improve the process parameters to achieve. It should be particularly pointed out that all similar replacements and changes are obvious to those skilled in the art, and they all belong to the scope protected by the present application. The method and application of the present application have been described by preferred embodiments, and relevant personnel can obviously modify or appropriately change and combine the method and application herein without departing from the content, spirit and scope of the present application, to realize and apply the present application technology.

[0032] The application provides a preparation method of an aqueous hydroxyl acrylic resin, comprising the following steps:

[0033] A) mixing a reactive solvent and a core layer mixture, and heating to react to obtain the core layer;

[0034] B) mixing the active POSS oligomer and the core layer, and reacting to obtain an intermediate layer;

[0035] C) mixing the intermediate layer, a reactive solvent and a shell layer mixture, and heating to react to obtain a three-layer structure material;

[0036] D) mixing the three-layer structure material with an initiator, a neutralizing agent and water, and dispersing to obtain the product.

[0037] The application provides a preparation method of a multi-branched aqueous hydroxyl acrylic resin, which comprises the following steps:

[0038] In some preferred embodiments of the application, the preparation method is as follows:

[0039] The reactive solvent and part of the core layer mixture are mixed, and after 10-60 min of reaction, the remaining part of the core layer mixture is added dropwise; after the dropwise addition is completed, the mixture is kept for 2-4 h; the reaction temperature is 90-150 DEG C; and the dropwise addition time is 2-4 h.

[0040] In some preferred embodiments of the application, the preparation method is as follows:

[0041] The reactive solvent and part of the core layer mixture are mixed, and after 20-50 min of reaction, the remaining part of the core layer mixture is added dropwise; after the dropwise addition is completed, the mixture is kept for 2-3.5 h; the reaction temperature is 100-140 DEG C; and the dropwise addition time is 2.5-3.5 h.

[0042] The mass ratio of the part of the core layer mixture to the remaining part of the core layer mixture is preferably 1-10:90-99, more preferably 2-8:91-98, and most preferably 4:96.

[0043] The reactive solvent comprises glycidyl t-butyl carbonate.

[0044] The core layer mixture comprises BA, MMA, HEA, MAA, di-t-butyl peroxide, dodecyl mercaptan and glycidyl t-butyl carbonate.

[0045] The preparation of the core layer mixture preferably comprises mixing BA, MMA, HEA, MAA, di-t-butyl peroxide, dodecyl mercaptan and glycidyl t-butyl carbonate for 10-20 min.

[0046] In one preferred embodiment of the present application,

[0047] The mass ratio of the BA, MMA, HEA, MAA, di-tert-butyl peroxide, dodecyl mercaptan and glycidyl t-butyl carbonate is 0-25:0-20:5-40:2-10:0.2-3:0.1-2:0-15; more preferably 10-20:5-15:10-30:3-8:0.5-2.5:0.5-1.5:3-12;

[0048] The active POSS oligomer is mixed with the core layer to react, and an intermediate layer is obtained.

[0049] The obtained active POSS oligomer is preferably added to the core layer prepolymer, and since the active POSS oligomer contains polymerizable radicals, the reaction temperature is preferably 95-115°C; the reaction is kept for 30 min-2 h; more preferably 40 min-100 min.

[0050] The preparation method of the active POSS oligomer in the present application is as follows: taking vinyl triethoxysilane as a raw material and hydrochloric acid as a catalyst to react, and OvPOSS is obtained;

[0051] The OvPOSS is dissolved in a mixture of butyl acrylate and methyl methacrylate, a solvent is added, and then an initiator is added dropwise to start polymerization, and an active POSS oligomer is obtained.

[0052] In one preferred embodiment of the present application, the preparation method of the active POSS oligomer is as follows:

[0053] A mixed solution of ethanol and distilled water and A151 is added to a round-bottom flask, stirred at room temperature to fully mix and uniformly, and then concentrated hydrochloric acid is gradually added to adjust the pH to about 3. The round-bottom flask is placed in a constant-temperature water bath, heated to 60°C for about 10 h, and after the reaction is completed, the reaction product is cooled to room temperature, and white crystalline powder is obtained by filtration, washed twice with cyclohexane and vacuum dried. The prepared white powder is recrystallized in tetrahydrofuran and methanol (1:3), vacuum dried to obtain white crystal product, i.e. octavinylsilsesquioxane (OvPOSS).

[0054] The above OvPOSS is dissolved in a mixture of butyl acrylate and methyl methacrylate, then glycidyl t-butyl carbonate is added as a solvent, and then a glycidyl t-butyl carbonate initiator is added dropwise to start polymerization, and the initiator is used in excess, and an active POSS oligomer is obtained.

[0055] The reaction process is as follows:

[0056]

[0057] Mixing the intermediate layer, the reactive solvent and the shell layer mixed solution, heating and reacting to obtain a three-layer structure material.

[0058] More preferably, the specific process is as follows: mixing the reactive solvent and part of the shell layer mixed solution, adding the remaining part of the shell layer mixed solution dropwise after 20-50 min of reaction, and keeping the mixture at temperature for 2.5-3.5 h after the dropwise addition is completed.

[0059] More preferably, the specific process is as follows: mixing the reactive solvent and part of the shell layer mixed solution, adding the remaining part of the shell layer mixed solution dropwise after 20-50 min of reaction, and keeping the mixture at temperature for 2.5-3.5 h after the dropwise addition is completed.

[0060] More preferably, the specific process is as follows: mixing the reactive solvent and part of the shell layer mixed solution, adding the remaining part of the shell layer mixed solution dropwise after 20-50 min of reaction, and keeping the mixture at temperature for 2.5-3.5 h after the dropwise addition is completed.

[0061] More preferably, the specific process is as follows: mixing the reactive solvent and part of the shell layer mixed solution, adding the remaining part of the shell layer mixed solution dropwise after 20-50 min of reaction, and keeping the mixture at temperature for 2.5-3.5 h after the dropwise addition is completed.

[0062] The shell layer mixed solution comprises BA, MMA, HEA, MAA, di-t-butyl peroxide, dodecyl mercaptan and glycidyl t-butyl carbonate.

[0063] In one of the preferred embodiments of the present application, the mass ratio of BA, MMA, HEA, MAA, di-t-butyl peroxide, dodecyl mercaptan and glycidyl t-butyl carbonate is 0-15:0-80:0-10:0.5-5:0.2-3:0-2:0-10, more preferably 10-20:5-15:10-30:3-8:0.5-2.5:0.5-1.5:3-12.

[0064] The preparation of the shell layer mixed solution preferably comprises mixing BA, MMA, HEA, MAA, di-t-butyl peroxide, dodecyl mercaptan and glycidyl t-butyl carbonate for 10-20 min.

[0065] The reactive solvent comprises glycidyl t-butyl carbonate.

[0066] Mixing the three-layer structure material with an initiator, a neutralizing agent and water, and dispersing to obtain the product.

[0067] The step D) of the present application is specifically as follows:

[0068] Mixing the three-layer structure material with an initiator, keeping the mixture at temperature for 3-6 h, then cooling to 50-90 ℃, adding a neutralizing agent and neutralizing for 30-60 min, cooling to 20-80 ℃, adding water, mixing and dispersing to obtain the product.

[0069] The step D) is more preferably specifically:

[0070] After the three-layer structure material is mixed with the initiator and kept for 3-5h, the temperature is lowered to 50-80℃, the neutralizer is added and neutralized for 40-60min; the temperature is lowered to 25-70℃, water is added, mixed and dispersed, and the product is obtained.

[0071] The initiator includes di-t-butyl peroxide; the adding amount of the initiator is 0.01-1wt% of the three-layer structure; more preferably 0.1-0.9wt%.

[0072] The neutralizer includes triethylamine; the adding amount of the neutralizer is determined according to the amount of MAA used, which is 0.8-1.5 times of the molar amount of carboxyl in MAA.

[0073] The dispersion is high-speed stirring dispersion for 30-60min; more preferably 40-60min.

[0074] The application provides a water-based hydroxyl acrylic resin prepared by the preparation method in any one of the above technical solutions.

[0075] The application has been clearly described for the above preparation method, and will not be repeated here.

[0076] The core layer is a polyacrylate with more soft monomers and containing most of the hydroxyl groups, the intermediate layer is a self-made reactive POSS oligomer, and the shell layer is a polyacrylate with more hard monomers and containing a small part of the hydroxyl groups. The modified POSS oligomer is used to connect the shell layer and the core layer, and the introduction of the POSS improves the Tg and the molecular weight, and the surface has better hydrophobicity.

[0077] The application uses the self-made reactive POSS oligomer, designs the core-shell structure, reasonably distributes the hydroxyl position, overcomes the problem of high viscosity of the water-based hydroxyl acrylic resin with high solid content, and the introduction of the POSS makes the resin have certain hydrophobicity, improves the tg of the overall resin, makes the resin have excellent water resistance and fast drying property, and due to the introduction of the POSS structure, the hydroxypropyl resin as a finish has better wear resistance.

[0078] The application provides a water-based coating for rail transit, which comprises the multi-branched water-based hydroxyl acrylic resin in the above technical solution.

[0079] The application has been clearly described for the above water-based hydroxyl acrylic resin, and will not be repeated here.

[0080] The application provides a preparation method of an aqueous hydroxyl acrylic resin, comprising the following steps: A) mixing a reactive solvent and a core layer mixed solution, and heating and reacting to obtain a core layer; B) mixing an active POSS oligomer and the core layer, and reacting to obtain an intermediate layer; C) mixing the intermediate layer, a reactive solvent and a shell layer mixed solution, and heating and reacting to obtain a three-layer structure material; and D) mixing the three-layer structure material with an initiator, a neutralizing agent and water, and dispersing to obtain the product. By means of the three-layer structure, the active POSS oligomer is used as the intermediate layer, the hydroxyl content of the hydroxyl acrylic resin is improved, the molecular weight and the compactness of the paint film are improved, the performance of the paint film after curing is more excellent, and the paint film has good hydrophobicity and wear resistance.

[0081] In order to further illustrate the application, the aqueous hydroxyl acrylic resin, the preparation method thereof and the aqueous coating for rail transit provided by the application are described in detail below in combination with examples.

[0082] Example 1

[0083] First, octavinylsilsesquioxane (OvPOSS) is prepared:

[0084] The method for preparing OvPOSS by using vinyltriethoxysilane (A151) is mature, simple to operate and easy to control. According to a reference, by using vinyltriethoxysilane as a raw material and hydrochloric acid as a catalyst, high-purity octavinylsilsesquioxane (OvPOSS) can be prepared by controlling the reaction process and the raw materials. 245 mL of ethanol, 30 mL of distilled water and 0.5 mol of A151 mixed solution are added into a 500 mL round-bottom flask, and stirred at room temperature to make them fully mixed and uniform. Then, concentrated hydrochloric acid is gradually added to adjust the pH to about 3. The round-bottom flask is placed in a constant-temperature water bath, and heated to 60 ℃ for about 10 h. After the reaction is completed, the reaction product is cooled to room temperature, and filtered to obtain white crystalline powder. The white powder is washed twice with cyclohexane and vacuum dried. The prepared white powder is recrystallized in tetrahydrofuran and methanol (1:3), and vacuum dried to obtain white crystalline product, i.e., octavinylsilsesquioxane (OvPOSS).

[0085] Example 2

[0086] Preparation of the active POSS oligomer (intermediate layer): 2 g of OvPOSS prepared in Example 1 is dissolved in a mixture of 5 g of butyl acrylate and 5 g of methyl methacrylate, and then 2 g of glycidyl t-butyl carbonate is added as a solvent. Then, 0.5 g of t-butyl carbonate initiator is added dropwise, and the temperature is kept at 95 ℃ to start polymerization. The initiator is used in excess, and the active POSS oligomer is obtained.

[0087] Preparation of the core layer:

[0088] Preparation of core layer mixed solution: 11 g of BA, 4 g of MMA, 22 g of HEA, 3 g of MAA, 1 g of di-t-butyl peroxide, 0.6 g of dodecyl mercaptan, and 5 g of glycidyl t-butyl ether were mixed for 20 minutes and used as prepared;

[0089] Synthesis of core structure: 6 g of glycidyl t-butyl ether was added to the reaction kettle, and the temperature was raised to 110°C; then 3.5 wt% of the core layer mixed solution was added to the reaction kettle, and after 30 minutes, the remaining core layer mixed solution was added dropwise, and the dropwise addition was completed at a uniform speed of 2.5 h; after the dropwise addition was completed, the temperature was maintained for 2 h;

[0090] Preparation of intermediate layer:

[0091] The active POSS oligomer obtained above was added to the core layer prepolymer prepared above after the temperature maintenance was completed, and since the active POSS oligomer contains polymerizable radicals, the temperature was maintained at 115°C, and the reaction was maintained for 60 min;

[0092] Preparation of shell layer:

[0093] Preparation of shell layer mixed solution: 5 g of BA, 40 g of MMA, 5 g of HEA, 1 g of MAA, 1 g of di-t-butyl peroxide, 0.9 g of dodecyl mercaptan, and 3 g of glycidyl t-butyl ether were mixed for 20 minutes and used as prepared;

[0094] Synthesis of shell structure: 7 g of glycidyl t-butyl ether was added to the reaction kettle, and the temperature was maintained at 115°C; then 4 wt% of the shell layer mixed solution was added to the reaction kettle, and after 40 minutes, the remaining shell layer mixed solution was added dropwise, and the dropwise addition was completed at a uniform speed of 3 h; after the dropwise addition was completed, the temperature was maintained for 2.5 h; then 0.5 g of di-t-butyl peroxide was added, and the temperature was maintained for 3 h;

[0095] Neutralization: the temperature was lowered to 55°C, 6 g of triethylamine neutralizer was added, and the neutralization was maintained for 40 min;

[0096] Dispersion: the temperature was lowered to 30°C, 155 g of deionized water was added, and the dispersion was maintained for 50 min at high speed stirring to obtain an aqueous acrylic dispersion.

[0097] Example 3

[0098] Preparation of active POSS oligomer (intermediate layer): 2 g of OvPOSS prepared in Example 1 above was dissolved in a mixture of 4 g of butyl acrylate and 6 g of methyl methacrylate, then 2 g of glycidyl t-butyl ether was added as a solvent, then 0.5 g / 3 g of glycidyl t-butyl ether initiator was added dropwise, the temperature was maintained at 95°C, and the polymerization was started, the initiator was used in excess, and an active POSS oligomer was obtained.

[0099] Preparation of core layer:

[0100] Preparation of core layer mixture: Mix 10g BA, 5g MMA, 20g HEA, 5g MAA, 1g di-tert-butyl peroxide, 0.6g dodecyl mercaptan, and 5g glycidyl tert-carbonate for 20 minutes and set aside.

[0101] Synthesis of the core structure: 6.5 g of glycidyl tert-carbonate, a reactive solvent, was added to the reaction vessel and the temperature was raised to 110 °C; then 4 wt% of the core layer mixture was added to the reaction vessel, and after 30 minutes, the remaining core layer mixture was added dropwise at a uniform rate for 2.5 h to complete the addition; after the addition was completed, the mixture was kept at the temperature for 2 h.

[0102] Preparation of the intermediate layer:

[0103] The active POSS oligomer obtained above was added to the core layer prepolymer that had been kept at the above temperature. Since the active POSS oligomer contains polymerizable free radicals, the temperature was kept at 115°C and the reaction was carried out for 60 minutes.

[0104] Shell preparation:

[0105] Preparation of shell mixture: Mix 6g BA, 38g MMA, 6g HEA, 1g MAA, 1g di-tert-butyl peroxide, 0.9g dodecyl mercaptan, and 3g glycidyl tert-carbonate for 20 minutes and set aside.

[0106] Synthesis of the shell structure: 7.5 g of glycidyl tert-carbonate, a reactive solvent, was added to the reaction vessel at 115 °C; then 5 wt% of the shell mixture was added to the reaction vessel. After 40 minutes, the remaining shell mixture was added dropwise at a uniform rate over 3 hours; after the addition was complete, the mixture was kept at this temperature for 2.5 hours; then 0.7 g of di-tert-butyl peroxide was added, and the mixture was kept at this temperature for 3 hours.

[0107] Neutralization: Cool to 55℃, add 6.5g of triethylamine neutralizing agent, and neutralize for 50 minutes;

[0108] Dispersion: Cool to 30°C, add 150g of deionized water, and disperse at high speed for 50 minutes to obtain an aqueous acrylic dispersion.

[0109] Example 4

[0110] Preparation of active POSS oligomers (intermediate layer): 2g of OvPOSS prepared in Example 1 above was dissolved in a mixture of 6g butyl acrylate and 4g methyl methacrylate, and then 2g glycidyl tert-carbonate was added as a solvent. Then, 0.5g / 3g glycidyl tert-carbonate initiator was added dropwise. The temperature was maintained at 100℃ to start polymerization. The amount of initiator was in excess, and active POSS oligomers were obtained.

[0111] Preparation of the core layer:

[0112] Preparation of core layer mixture: Mix 6g BA, 4g EA, 4g MMA, 21g HEA, 5g MAA, 1g di-tert-butyl peroxide, 0.6g dodecyl mercaptan, and 5g glycidyl tert-carbonate for 20 minutes and set aside.

[0113] Synthesis of the core structure: 6.5 g of glycidyl tert-carbonate, a reactive solvent, was added to the reaction vessel and the temperature was raised to 110 °C; then 4 wt% of the core layer mixture was added to the reaction vessel, and after 30 minutes, the remaining core layer mixture was added dropwise at a uniform rate for 2.5 h to complete the addition; after the addition was completed, the mixture was kept at the temperature for 2 h.

[0114] Preparation of the intermediate layer:

[0115] The active POSS oligomer obtained above was added to the core layer prepolymer that had been kept at the above temperature. Since the active POSS oligomer contains polymerizable free radicals, the temperature was kept at 115°C and the reaction was carried out for 60 minutes.

[0116] Shell preparation:

[0117] Preparation of shell mixture: Mix 4g BA, 30g MMA, 10g St, 6g HEA, 1g MAA, 1g di-tert-butyl peroxide, 0.9g dodecyl mercaptan, and 3g glycidyl tert-carbonate for 20 minutes and set aside.

[0118] Synthesis of the shell structure: 7.5 g of glycidyl tert-carbonate, a reactive solvent, was added to the reactor at 115 °C; then 4 wt% of the shell mixture was added to the reactor. After 40 minutes, the remaining shell mixture was added dropwise over a uniform rate for 3 hours until the addition was complete; after the addition was complete, the mixture was kept at this temperature for 2.5 hours; then 0.8 g of di-tert-butyl peroxide was added and the mixture was kept at this temperature for 3 hours.

[0119] Neutralization: Cool to 55℃, add 8g of dimethylethanolamine neutralizing agent, and neutralize for 60 minutes;

[0120] Dispersion: Cool to 30°C, add 160g of deionized water, and disperse at high speed for 60 minutes to obtain an aqueous acrylic dispersion.

[0121] Comparative Example 1

[0122] Preparation of the core layer:

[0123] Preparation of core layer mixture: Mix 9g BA, 4g EA, 6g MMA, 12g HEA, 5g MAA, 1g di-tert-butyl peroxide, 0.6g dodecyl mercaptan, and 5g glycidyl tert-carbonate for 20 minutes and set aside.

[0124] Synthesis of core structure: 6.5g of reactive solvent glycidyl ester of versatic acid was added into the reactor, and the temperature was raised to 110℃; then 4wt% of the core layer mixed solution was added into the reactor, and the remaining core layer mixed solution was added dropwise after 30 minutes, and the dropwise addition was completed in 2.5h; after the dropwise addition was completed, the temperature was kept for 2h;

[0125] Preparation of shell layer:

[0126] Preparation of shell layer mixed solution: 7g of BA, 33g of MMA, 10g of St, 3g of HEA, 1g of MAA, 1g of di-t-butyl peroxide, 0.9g of dodecyl mercaptan, and 3g of glycidyl ester of versatic acid were mixed for 20 minutes, and were ready for use;

[0127] Synthesis of shell structure: 7.5g of reactive solvent glycidyl ester of versatic acid was added into the reactor, and the temperature was 115℃; then 4wt% of the shell layer mixed solution was added into the reactor, and the remaining shell layer mixed solution was added dropwise after 40 minutes, and the dropwise addition was completed in 3h; after the dropwise addition was completed, the temperature was kept for 2.5h; then 0.8g of di-t-butyl peroxide was added, and the temperature was kept for 3h;

[0128] Neutralization: the temperature was lowered to 55℃, 8g of dimethyl ethanolamine neutralizer was added, and the neutralization was performed for 60 minutes;

[0129] Dispersion: the temperature was lowered to 30℃, 200g of deionized water was added, and the dispersion was performed for 60 minutes under high-speed stirring, and an aqueous acrylic dispersion was obtained.

[0130] Table 1

[0131] Test Example 2 Example 3 Example 4 Comparative Example 1 Hydroxyl content % 3.9 3.8 3.9 2.2 Solids % 45.1 48.6 44.8 36.6 Viscosity mPa.s 956 1100 1015 2500

[0132] The above only describes the preferred embodiments of the present application, and it should be noted that for those skilled in the art, several improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A method for preparing an aqueous hydroxyl acrylic resin, characterized in that, Includes the following steps: A) A reactive solvent and a core layer mixture are mixed and heated to obtain a core layer; the core layer mixture comprises BA, MMA, HEA, MAA, di-tert-butyl peroxide, dodecyl mercaptan, and glycidyl tert-carbonate; the mass ratio of BA, MMA, HEA, MAA, di-tert-butyl peroxide, dodecyl mercaptan, and glycidyl tert-carbonate is 10~20:5~15:10~30:3~8:0.5~2.5:0.5~1.5:3~12; B) The active POSS oligomer and the core layer are mixed and reacted to obtain the intermediate layer; the preparation method of the active POSS oligomer is as follows: using vinyltriethoxysilane as raw material and hydrochloric acid as catalyst, the reaction is carried out to obtain OvPOSS; OvPOSS was dissolved in a mixture of butyl acrylate and methyl methacrylate, solvent was added, and then an initiator was added dropwise to start polymerization, yielding active POSS oligomers; C) The intermediate layer, reactive solvent, and shell mixture are mixed and heated to obtain a three-layer structure; the shell mixture includes BA, MMA, HEA, MAA, di-tert-butyl peroxide, dodecyl mercaptan, and glycidyl tert-carbonate; the mass ratio of BA, MMA, HEA, MAA, di-tert-butyl peroxide, dodecyl mercaptan, and glycidyl tert-carbonate is 0~15:0~80:0~10:0.5~5:0.2~3:0~2:0~10; D) Mix the three-layer structured material with an initiator, a neutralizing agent, and water, and disperse to obtain the final product.

2. The preparation method according to claim 1, characterized in that, Step A) specifically involves: The reactive solvent and a portion of the core-layer mixture are mixed and reacted for 10-60 minutes. The remaining portion of the core-layer mixture is then added dropwise. After the addition is complete, the mixture is kept at this temperature for 2-4 hours. The reaction temperature is 90-150°C, and the addition time is 2-4 hours.

3. The preparation method according to claim 2, characterized in that, The mass ratio of the partial core-layer mixture to the remaining part of the core-layer mixture is 1~10:90~99; The reactive solvent includes glycidyl tert-carbonate.

4. The preparation method according to claim 1, characterized in that, The reaction time in step B) is 30 min to 2 h.

5. The preparation method according to claim 1, characterized in that, Step C) specifically involves: The reactive solvent and a portion of the shell mixture are mixed and reacted for 10-60 minutes. The remaining portion of the shell mixture is then added dropwise. After the addition is complete, the mixture is kept at this temperature for 2-4 hours. The reaction temperature is 90-150℃. The addition time is 2-4 hours. The mass ratio of the portion of the shell mixture to the remaining portion of the shell mixture is 1-10:90-99. The reactive solvent includes glycidyl tert-carbonate.

6. The preparation method according to claim 1, characterized in that, Step D) specifically refers to: The three-layer structure material is mixed with the initiator and kept at a temperature of 3-6 hours, then cooled to 50-90°C, and neutralized with a neutralizing agent for 30-60 minutes; then cooled to 20-80°C, water is added, mixed, and dispersed to obtain the final product. The initiator comprises di-tert-butyl peroxide; the amount of the initiator added is 0.01~1 wt% of the three-layer structure. The neutralizing agent includes triethylamine; the amount of the neutralizing agent added is 0.8 to 1.5 times the molar amount of carboxyl groups in MAA; The dispersion is carried out by high-speed stirring for 30-60 minutes.

7. A waterborne hydroxyl acrylic resin, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 6.

8. A water-based coating for rail transit, characterized in that, Includes the aqueous hydroxyl acrylic resin as described in claim 7.

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