Silicon dioxide composite acrylic acid/epoxy water-based resin and preparation method thereof

文档序号:802550 发布日期:2021-03-26 浏览:10次 中文

阅读说明:本技术 一种二氧化硅复合丙烯酸/环氧水性树脂及其制备方法 (Silicon dioxide composite acrylic acid/epoxy water-based resin and preparation method thereof ) 是由 姜美佳 李维亚 秦玉猛 彭程 付绍祥 洪杰 于 2020-12-07 设计创作,主要内容包括:本发明涉及一种二氧化硅复合丙烯酸/环氧水性树脂及其制备方法。本发明的一种二氧化硅复合丙烯酸/环氧水性树脂的制备方法包括如下步骤:将环氧树脂和单体杂化形成丙烯酸/环氧杂化体;制备Janus型二氧化硅颗粒水分散液;将制备的Janus型二氧化硅颗粒水分散液加入丙烯酸/环氧杂化体中,形成所述的二氧化硅复合丙烯酸/环氧树脂。该方法的功能单体丙烯酸或甲基丙烯酸的用量更少,残存的羧基相对更少,制备的水性树脂更稳定,储存稳定性大大提高,形成类树莓状结构,使树脂的耐腐蚀性、耐候性以及抗老化性都有进一步提高。(The invention relates to a silicon dioxide composite acrylic acid/epoxy water-based resin and a preparation method thereof. The preparation method of the silicon dioxide composite acrylic acid/epoxy water-based resin comprises the following steps: hybridizing an epoxy resin and a monomer to form an acrylic acid/epoxy hybrid; preparing an aqueous dispersion of Janus type silica particles; adding the prepared Janus type silicon dioxide particle aqueous dispersion into an acrylic acid/epoxy hybrid to form the silicon dioxide composite acrylic acid/epoxy resin. The method has the advantages that the dosage of the functional monomer acrylic acid or methacrylic acid is less, the residual carboxyl is relatively less, the prepared water-based resin is more stable, the storage stability is greatly improved, a raspberry-like structure is formed, and the corrosion resistance, the weather resistance and the aging resistance of the resin are further improved.)

1. the preparation method of the silicon dioxide composite acrylic acid/epoxy resin is characterized by comprising the following steps: the method comprises the following steps:

(1) hybridizing an epoxy resin and a monomer to form an acrylic acid/epoxy hybrid;

(2) preparing Janus type silicon dioxide particles with one side containing alkyl and the other side not modified, and then dispersing the Janus type silicon dioxide particles in deionized water to form an aqueous dispersion of the Janus type silicon dioxide particles;

(3) and (3) adding the Janus type silicon dioxide particle aqueous dispersion prepared in the step (2) into the acrylic acid/epoxy hybrid prepared in the step (1) to form the silicon dioxide composite acrylic acid/epoxy resin.

2. The method for preparing silica composite acrylic/epoxy resin according to claim 1, wherein: the step (1) comprises the following steps:

adding 50-70 parts by mass of epoxy resin into a container, heating to 110 ℃ of temperature, then adding 20-40 parts by mass of solvent at the rotation speed of 150-300rpm, then increasing the rotation speed to 600rpm of 400-400 and connecting nitrogen, then dropping a mixed solution consisting of 3-9 parts by mass of methacrylic acid and 1-2 parts by mass of initiator for 1-3h, then heating to 140 ℃ of temperature and keeping the temperature for 0.5-2h, then adding 0.1-0.5 part by mass of initiator, and continuing keeping the temperature for 2-4h to obtain an acrylic acid/epoxy intermediate;

adding 20-40 parts by mass of solvent into a second container, increasing the rotating speed to 400-600rpm, raising the temperature to 120 ℃ for 100-120 ℃, then dripping a mixture consisting of 40-60 parts by mass of monomer, 1-2 parts by mass of initiator and 10-20 parts by mass of acrylic acid/epoxy intermediate prepared in the step (1) for 1-3h, then preserving heat for 20-60min, then adding 0.1-0.5 part by mass of initiator, and continuing preserving heat for 1-3 h; then cooling to room temperature to obtain the acrylic acid/epoxy hybrid.

3. The method for preparing silica composite acrylic/epoxy resin according to claim 1, wherein: the step (2) comprises the following steps:

adding 50-150 parts by mass of alkaline silica sol into a third container, heating to 65-85 ℃, adding 15-45 parts by mass of paraffin wax under the stirring at the stirring speed of 250-3000 rpm, continuing to stir for 20-60min, and then increasing the rotating speed to 1500-3000rpm and continuing to stir for 10-30 min; then cooling to room temperature and filtering to obtain paraffin particles containing the silica;

dispersing the obtained paraffin particles containing silicon dioxide in 50-250 parts by mass of ethanol at room temperature, then adding 5-20 parts by mass of deionized water and 2-10 parts by mass of alkaline neutralizing agent, then adding 2-10g parts by mass of silane coupling agent, then stirring for 2-4h at the stirring speed of 100-500rpm, then heating to 85-95 ℃, continuing stirring for 1-3h, then cooling to room temperature, and finally centrifuging to remove the supernatant to obtain the paraffin particles containing Janus type silicon dioxide particles;

finally, the paraffin particles of the obtained silicon dioxide are centrifugally extracted by chloroform to remove the paraffin, so that Janus type silicon dioxide particles are obtained.

4. The method for preparing silica composite acrylic/epoxy resin according to claim 1, wherein: in the step (2), the mass percentage of the Janus type silicon dioxide particles in the Janus type silicon dioxide particle water dispersion liquid is between 5 and 20 percent.

5. The method for preparing silica composite acrylic/epoxy resin according to claim 1, wherein: the step (3) comprises the following steps:

heating the acrylic acid/epoxy hybrid resin obtained in the step (1) to 50-70 ℃, then increasing the rotating speed to 1500-3000rpm, then adding 5-15 parts by mass of an alkaline neutralizing agent, then dropping 40-65 parts by mass of the Janus type silicon dioxide particle aqueous dispersion prepared in the step (2), wherein the dropping time is 60-120min, then controlling the stirring speed to 2500-3500rpm, then adding 20-40 parts by mass of the Janus type silicon dioxide particle aqueous dispersion prepared in the step (2), then controlling the stirring speed to 1000-3000rpm, and continuing stirring for 20-60min to obtain the silicon dioxide composite acrylic acid/epoxy resin.

6. The method for preparing silica composite acrylic/epoxy resin according to claim 2, wherein: the initiator is a thermal decomposition type initiator.

7. The method for preparing silica composite acrylic/epoxy resin according to claim 2, wherein: the monomer is one of acrylate monomer, methacrylate monomer and styrene monomer or is formed by mixing the acrylate monomer, the methacrylate monomer and the styrene monomer in any proportion.

8. The method for preparing a silica composite acrylic/epoxy resin according to claim 3 or 5, characterized in that: the alkaline neutralizing agent is ammonia water or N, N-dimethylethanolamine water solution with the mass fraction of 50%.

9. The method for preparing silica composite acrylic/epoxy resin according to claim 3, wherein:

the particle size of the alkaline silica sol is between 22 and 25 nm; the solid content is 40 percent; the pH is between 9 and 10;

the silane coupling agent is 3- (2, 3-epoxypropoxy) propyl trimethoxy silane.

10. The silicon dioxide composite acrylic acid/epoxy resin is characterized in that: prepared by the method of any one of claims 1-9.

Technical Field

The invention relates to the field of coatings, and particularly relates to a silicon dioxide composite acrylic acid/epoxy water-based resin and a preparation method thereof.

Background

Acrylic resins are excellent in stain resistance, weather resistance and toughness, and epoxy resins are good in adhesion, adhesion and corrosion resistance, so that acrylic/epoxy hybrid aqueous resins have been studied by many people, and common methods include a cold-blending method, a solution polymerization method and an emulsion polymerization method. In the cold-blending method, due to the compatibility problem, the layering phenomenon always occurs, and the prepared paint film has poor performance and cannot meet the requirements; in the solution polymerization method, since the epoxy group cannot be completely eliminated, the storage stability thereof tends to be insufficient for industrial requirements; in the emulsion polymerization method for preparing the acrylic acid/epoxy hybrid water-based resin, because the grafting reaction initiated by the active points generated by the hydrogen abstraction of the initiator free radicals is not easy to occur in the emulsion environment, the grafting density is low, the using amount of the emulsifier is large, and the product meeting the requirements is difficult to obtain.

It is also reported in literature that acrylic acid or epoxy and hybrid thereof are subjected to inorganic modification, but inorganic nanoparticles are generally introduced into an organic system, so that the performance of the composite material is improved on the premise of not damaging the characteristics of an organic matrix. At present, cold splicing is commonly used for inorganic modification, namely, inorganic substances with functions are doped in selected polymers, especially inorganic nanoparticles such as silicon dioxide, zinc oxide, titanium dioxide and the like. In consideration of the surface energy difference between inorganic matters and organic matters, the composite emulsion/dispersion prepared by the cold splicing method has poor stability, and the characteristic of poor stability can be improved by modifying inorganic nanoparticles, but the stability problem cannot be thoroughly solved.

Disadvantage 1: the water-based acrylic acid/epoxy system prepared by the cold-splicing method is easy to layer due to the compatibility problem, and the performance of a paint film is poor;

the disadvantage 2 is that the solution polymerization for preparing the water-based acrylic acid/epoxy hybrid has poor storage stability due to the existence of unreacted carboxyl and epoxy, thus being difficult to meet the industrial requirement;

the disadvantage 3 is that the acrylic acid/epoxy hybrid water-based resin prepared by the emulsion polymerization method has low grafting density and large emulsifier dosage because the grafting reaction initiated by the active site generated by the hydrogen abstraction of the initiator free radical in the emulsion environment is not easy to occur, and the product meeting the requirement is difficult to obtain.

Disclosure of Invention

The invention provides a silicon dioxide composite acrylic acid/epoxy water-based resin and a preparation method thereof, the preparation method of the silicon dioxide composite acrylic acid/epoxy water-based resin is simple and feasible, and the acrylic acid/epoxy hybrid paint film has the advantages of good performance, good storage stability, high hardness after film formation, excellent corrosion resistance, good weather resistance and excellent comprehensive performance.

The preparation method of the silicon dioxide composite acrylic acid/epoxy resin comprises the following steps:

(1) hybridizing an epoxy resin and a monomer to form an acrylic acid/epoxy hybrid;

(2) preparing Janus type silicon dioxide particles with one side containing alkyl and the other side not modified, and then dispersing the Janus type silicon dioxide particles in deionized water to form Janus type silicon dioxide particle water dispersion liquid;

(3) and (3) adding the Janus type silicon dioxide particle aqueous dispersion prepared in the step (2) into the acrylic acid/epoxy hybrid prepared in the step (1) to form the silicon dioxide composite acrylic acid/epoxy resin.

Preferably, step (1) comprises the steps of:

adding 50-70 parts by mass of epoxy resin into a container, heating to 110 ℃ of temperature, then adding 20-40 parts by mass of solvent at the rotation speed of 150-300rpm, then increasing the rotation speed to 600rpm of 400-400 and connecting nitrogen, then dropping a mixed solution consisting of 3-9 parts by mass of methacrylic acid and 1-2 parts by mass of initiator for 1-3h, then heating to 140 ℃ of temperature and keeping the temperature for 0.5-2h, then adding 0.1-0.5 part by mass of initiator, and continuing keeping the temperature for 2-4h to obtain an acrylic acid/epoxy intermediate;

adding 20-40 parts by mass of solvent into a second container, increasing the rotating speed to 400-600rpm, raising the temperature to 120 ℃ for 100-120 ℃, then dripping a mixture consisting of 40-60 parts by mass of monomer, 1-2 parts by mass of initiator and 10-20 parts by mass of acrylic acid/epoxy intermediate prepared in the step (1) for 1-3h, then preserving heat for 20-60min, then adding 0.1-0.5 part by mass of initiator, and continuing preserving heat for 1-3 h; then cooling to room temperature to obtain the acrylic acid/epoxy hybrid.

Preferably, the step (2) comprises the steps of:

adding 50-150 parts by mass of alkaline silica sol into a third container, heating to 65-85 ℃, adding 15-45 parts by mass of paraffin wax under the stirring at the stirring speed of 250-3000 rpm, continuing to stir for 20-60min, and then increasing the rotating speed to 1500-3000rpm and continuing to stir for 10-30 min; then cooling to room temperature and filtering to obtain paraffin particles containing the silica;

dispersing the obtained paraffin particles containing silicon dioxide in 50-150 parts by mass of ethanol at room temperature, then adding 5-20 parts by mass of deionized water and 2-10 parts by mass of alkaline neutralizing agent, then adding 2-10g parts by mass of silane coupling agent, then stirring for 2-4h at the stirring speed of 100-500rpm, then heating to 85-95 ℃, continuing stirring for 1-3h, then cooling to room temperature, and finally centrifuging to remove the supernatant to obtain the paraffin particles containing Janus type silicon dioxide particles;

finally, the paraffin particles of the obtained silicon dioxide are centrifugally extracted by chloroform to remove the paraffin, so that Janus type silicon dioxide particles are obtained.

Preferably, the content of the Janus type silicon dioxide particles in the Janus type silicon dioxide particle water dispersion liquid in the step (2) is between 5 and 15 percent by mass.

Preferably, the step (3) comprises the steps of:

heating the acrylic acid/epoxy hybrid resin obtained in the step (1) to 50-70 ℃, then increasing the rotating speed to 1500-3000rpm, then adding 5-15 parts by mass of an alkaline neutralizing agent, then dropping 40-65 parts by mass of the Janus type silicon dioxide particle aqueous dispersion prepared in the step (2), wherein the dropping time is 60-120min, then controlling the stirring speed to 2500-3500rpm, then adding 20-40 parts by mass of the Janus type silicon dioxide particle aqueous dispersion prepared in the step (2), then controlling the stirring speed to 1000-3000rpm, and continuing stirring for 20-60min to obtain the silicon dioxide composite acrylic acid/epoxy resin.

The alkaline neutralizing agent is ammonia water or N, N-dimethylethanolamine water solution with the mass fraction of 50%.

Preferably, the initiator is a thermal decomposition type initiator;

the monomer is one of acrylate monomer, methacrylate monomer and styrene monomer or is formed by mixing the acrylate monomer, the methacrylate monomer and the styrene monomer according to any proportion.

Preferably, the particle size of the alkaline silica sol is between 22 and 25 nm; the solid content is 40 percent; the pH is between 9 and 10;

the silane coupling agent is 3- (2, 3-epoxypropoxy) propyl trimethoxy silane.

The silicon dioxide composite acrylic acid/epoxy resin is prepared by the method.

The principle is as follows: the main technical scheme of the invention is to prepare the silicon dioxide composite acrylic acid/epoxy water-based resin, firstly, preparing acrylic acid/epoxy hybrid, then preparing silicon dioxide nano particles, wherein the silicon dioxide nano particles are Janus nano particles, one surface of the silicon dioxide nano particles is modified by containing alkyl, the other surface of the silicon dioxide nano particles is unmodified, and the silicon dioxide nano particles are added with water in the preparation process of the acrylic acid/epoxy water-based resin, so that the silicon dioxide nano particles can be uniformly dispersed around the acrylic acid/epoxy water-based resin dispersion and can stabilize the acrylic acid/epoxy hybrid water-based resin.

In the step (1), carboxyl and epoxy group are used for reaction, and epoxy resin is grafted to an acrylate polymer chain to form acrylic acid/epoxy hybrid resin; when the silicon dioxide is modified in the step (2), the raw materials adopted are paraffin and partial solvent, and the finally used paraffin and solvent can be recycled; in the method for preparing the silicon dioxide-containing acrylic acid/epoxy waterborne resin, modified silicon dioxide and acrylic acid/epoxy resin are mutually fused to form a raspberry-shaped structure.

The water-based acrylic resin and the water-based epoxy resin mentioned in the background are cold spliced, have the problem of miscibility and are easy to separate; the solution polymerization method is easy to fail in thermal storage stability; the emulsion polymerization method easily causes that the grafting rate is low and cannot meet the requirement; the organic-inorganic hybridization also adopts physical blending, which is easy to cause agglomeration. The invention adopts a solution polymerization method combined with Janus silicon dioxide technology to prepare the silicon dioxide composite acrylic acid/epoxy water-based resin. The silicon dioxide can stabilize acrylic acid/epoxy hybrid, and can stabilize polymer under the condition of relatively hydrophobic property, so that the dosage of functional monomer acrylic acid or methacrylic acid can be reduced, and the polymer has relatively good hydrophobic property and relatively good heat storage stability. The solution polymerization is adopted to solve the problem of low grafting rate of emulsion polymerization.

Compared with the prior art, the invention has the following beneficial effects: compared with the conventional acrylic acid/epoxy hybrid water-based resin, the method has the advantages that the consumption of functional monomers of acrylic acid or methacrylic acid is less, the residual carboxyl is relatively less, the prepared water-based resin is more stable, the storage stability is greatly improved, meanwhile, inorganic silica nano particles are introduced, and a raspberry-like structure is formed by utilizing the difference of hydrophilicity and hydrophobicity, so that the corrosion resistance, the weather resistance and the aging resistance of the resin are further improved. The resin integrates the performances of acrylic acid, epoxy and inorganic nano particles, and can improve the comprehensive performances of the hardness, weather resistance, corrosion resistance, mechanical property and the like of a paint film when being applied to paint.

A special silicon dioxide doping process, namely adding silicon dioxide dispersion liquid in the phase inversion process of preparing the aqueous resin, wherein the silicon dioxide is embedded in the polymer;

the active ingredient of the prepared silicon dioxide dispersion liquid is Janus silicon dioxide nano-particles, namely one end of the silicon dioxide dispersion liquid is modified, and the other end of the silicon dioxide dispersion liquid is unmodified, so that the stability of a polymer dispersed in water can be improved, the agglomeration of inorganic nano-particles is prevented, and the stability of the whole system, particularly the heat storage stability, is improved;

the method is simple, the prepared composite dispersoid is not influenced in gloss, the hardness is greatly increased, and the salt spray resistance is improved.

The dispersion prepared by the method is stable, and has no layering and obvious viscosity change; the heat storage at 50 ℃ for 30 days has no abnormality, and meets the requirement of industrial application; when the coating is applied to a coating, the hardness of a paint film can reach more than 2H, and the artificial accelerated aging resistant time exceeds 1000H; meanwhile, the introduction of the inorganic nano particle silicon dioxide does not influence the performances of fullness, luster and the like of a paint film.

Drawings

FIG. 1 is a flow chart of the preparation method of the present invention.

Detailed Description

The invention will be further illustrated with reference to the following specific examples

Example 1

The preparation method of the silicon dioxide composite acrylic acid/epoxy resin comprises the following steps:

(1) hybridizing an epoxy resin and a monomer to form an acrylic acid/epoxy hybrid;

(2) preparing Janus type silicon dioxide particles with one side containing alkyl and the other side not modified, and then dispersing the Janus type silicon dioxide particles in deionized water to form Janus type silicon dioxide particle water dispersion liquid;

(3) and (3) adding the Janus type silicon dioxide particle aqueous dispersion prepared in the step (2) into the acrylic acid/epoxy hybrid prepared in the step (1) to form the silicon dioxide composite acrylic acid/epoxy resin.

The step (1) comprises the following steps:

adding 50g of epoxy resin into a container, heating to 100 ℃, then adding 20g of solvent at 200rpm, then increasing the rotating speed to 400rpm and connecting nitrogen, then dripping a mixed solution consisting of 3g of methacrylic acid and 1g of initiator for 1h, heating to 110 ℃, keeping the temperature for 0.5h, then adding 0.1g of initiator, and continuing to keep the temperature for 2h to obtain an acrylic acid/epoxy intermediate;

adding 20g of solvent into a second container, increasing the rotating speed to 400rpm, raising the temperature to 100 ℃, then dripping a mixture consisting of 40g of acrylate, 1g of initiator and 10g of acrylic acid/epoxy intermediate prepared in the step (1) for 1 hour, then preserving heat for 20min, then adding 0.1g of initiator, and continuing preserving heat for 1 hour; then cooling to room temperature to obtain the acrylic acid/epoxy hybrid.

The step (2) comprises the following steps:

adding 50g of alkaline silica sol into a third container, heating to 65 ℃, adding 15g of paraffin wax under the stirring of 250rpm, continuing to stir for 20min, and then increasing the rotating speed to 1500rpm and continuing to stir for 10 min; then the temperature is cooled to room temperature and filtered to obtain paraffin particles containing the silica;

dispersing the obtained paraffin particles containing silicon dioxide in 50g of ethanol at room temperature, then adding 5g of deionized water and 2g of ammonia water, then adding 2g of silane coupling agent, stirring at the stirring speed of 100rpm for 2h, then heating to 85 ℃, continuing stirring for 1 hour, then cooling to room temperature, and finally centrifuging to remove the supernatant to obtain the paraffin particles containing Janus type silicon dioxide particles;

finally, the paraffin particles of the obtained silicon dioxide are centrifugally extracted by chloroform to remove the paraffin, so that Janus type silicon dioxide particles are obtained.

Finally, ultrasonically dispersing the obtained Janus silicon dioxide nano particles in water to form Janus silicon dioxide nano particle water dispersion liquid;

the mass percentage of the Janus type silicon dioxide particles in the Janus type silicon dioxide particle water dispersion liquid in the step (2) is 5%.

The step (3) comprises the following steps:

heating the acrylic acid/epoxy hybrid resin obtained in the step (1) to 50 ℃, then increasing the rotating speed to 1500rpm, then adding 5g of 50% N, N-dimethylethanolamine aqueous solution, then dropping 40g of Janus type silicon dioxide particle aqueous dispersion prepared in the step (2), wherein the dropping time is between 60min, then controlling the stirring speed to be 2500rpm, then adding 20-40g of Janus type silicon dioxide particle aqueous dispersion prepared in the step (2), then controlling the stirring speed to be 1000rpm, and continuing stirring for 20min to obtain the silicon dioxide composite acrylic acid/epoxy resin.

The alkaline neutralizing agent is a 50% N, N-dimethylethanolamine aqueous solution.

Preferably, the initiator is a thermal decomposition type initiator (benzoyl peroxide);

the monomer is methacrylate monomer.

Preferably, the particle size of the alkaline silica sol is between 22 and 25 nm; the solid content is 40 percent; the pH is 10;

the silane coupling agent is 3- (2, 3-epoxypropoxy) propyl trimethoxy silane.

Example 2

The preparation method of the silicon dioxide composite acrylic acid/epoxy resin comprises the following steps:

(1) hybridizing epoxy resin and acrylate to form an acrylic acid/epoxy hybrid;

(2) preparing Janus type silicon dioxide particles with one side containing alkyl and the other side not modified, and then dispersing the Janus type silicon dioxide particles in deionized water to form Janus type silicon dioxide particle water dispersion liquid;

(3) and (3) adding the Janus type silicon dioxide particle aqueous dispersion prepared in the step (2) into the acrylic acid/epoxy hybrid prepared in the step (1) to form the silicon dioxide composite acrylic acid/epoxy resin.

The step (1) comprises the following steps:

adding 70g of epoxy resin E44 into a container, heating to 110 ℃, then adding 40g of solvent at 150rpm, then increasing the rotation speed to 600rpm, switching on nitrogen, then dripping a mixed solution consisting of 9g of methacrylic acid and 2g of initiator for 3 hours, then heating to 140 ℃, keeping the temperature for 2 hours, then adding 0.5g of initiator, and continuing to keep the temperature for 4 hours to obtain an acrylic acid/epoxy intermediate;

adding 40g of solvent into a second container, increasing the rotating speed to 600rpm, raising the temperature to 120 ℃, then dripping a mixture consisting of 60g of acrylate monomer, 2g of initiator and 20g of acrylic acid/epoxy intermediate prepared in the step (1) for 3 hours, then preserving heat for 60 minutes, then adding 0.5g of initiator, and continuing preserving heat for 3 hours; then cooling to room temperature to obtain the acrylic acid/epoxy hybrid.

The step (2) comprises the following steps:

adding 150g of alkaline silica sol into a third container, heating to 85 ℃, adding 45g of paraffin wax under the stirring of 250rpm, continuing to stir for 60min, and then increasing the rotating speed to 3000rpm and continuing to stir for 30 min; then cooling to room temperature and filtering to obtain paraffin particles containing the silica;

dispersing the obtained paraffin particles containing silicon dioxide in 150g of ethanol at room temperature, then adding 20g of deionized water and 10g of ammonia water, then adding 10gg of silane coupling agent, stirring at the stirring speed of 500rpm for 4h, then heating to 95 ℃, continuing stirring for 3 hours, then cooling to room temperature, and finally centrifuging to remove the supernatant to obtain the paraffin particles containing Janus type silicon dioxide particles;

finally, the paraffin particles of the obtained silicon dioxide are centrifugally extracted by chloroform to remove the paraffin, so that Janus type silicon dioxide particles are obtained.

Finally, ultrasonically dispersing the obtained Janus silicon dioxide nano particles in water to form Janus silicon dioxide nano particle water dispersion liquid;

the mass percentage of the Janus type silicon dioxide particles in the Janus type silicon dioxide particle water dispersion liquid in the step (2) is 15%.

The step (3) comprises the following steps:

heating the acrylic acid/epoxy hybrid resin obtained in the step (1) to 70 ℃, then increasing the rotating speed to 3000rpm, then adding 15g of 50% N, N-dimethylethanolamine aqueous solution, then dropping 65g of the Janus type silicon dioxide particle aqueous dispersion prepared in the step (2), wherein the dropping time is 120min, then controlling the stirring speed to be 3500rpm, then adding 40g of the Janus type silicon dioxide particle aqueous dispersion prepared in the step (2), then controlling the stirring speed to be 3000rpm, and continuing stirring for 60min to obtain the silicon dioxide composite acrylic acid/epoxy resin.

The alkaline neutralizing agent is ammonia water.

Preferably, the initiator is a thermal decomposition type initiator (benzoyl peroxide);

the monomer is acrylate monomer.

Preferably, the particle size of the alkaline silica sol is between 22 and 25 nm; the solid content is 40 percent; the pH is 9;

the silane coupling agent is 3- (2, 3-epoxypropoxy) propyl trimethoxy silane.

Example 3

A preparation method of silicon dioxide composite acrylic acid/epoxy water-based resin comprises the following steps:

(1) hybridizing an epoxy resin and a monomer to form an acrylic/epoxy hybrid:

adding 60g of epoxy resin E44 into a second container, heating to 110 ℃, adding 11g of ethylene glycol butyl ether and 21.2g of n-butanol, introducing nitrogen, dripping a mixed solution of 6g of methacrylic acid and 1.5g of benzoyl peroxide at the rotation speed of 500rpm, controlling the dripping time to be 2 hours, heating to 120 ℃, preserving heat for 1 hour, then adding 0.3g of benzoyl peroxide, and preserving heat for 3 hours at 120 ℃ to obtain an acrylic acid/epoxy intermediate;

adding 10g of ethylene glycol butyl ether and 20g of n-butanol into a third container while stirring at the temperature of 110 ℃, then dripping a mixture of 4.8g of methacrylic acid, 35g of butyl acrylate, 13.6g of methyl methacrylate, 15g of the acrylic acid/epoxy intermediate prepared in the step (2) and 1.3g of an initiator (benzoyl peroxide) at the rotation speed of 500rpm for 2 hours, then keeping the temperature for 30 minutes, then adding 0.3g of the initiator benzoyl peroxide, and keeping the temperature for 2 hours; then cooling to room temperature to obtain an acrylic acid epoxy hybrid;

(2) preparation of aqueous Janus silica nanoparticle dispersion

Adding 100g of alkaline silica sol into a first container, heating to 75 ℃, adding 30g of paraffin under the stirring of 250rpm, continuously stirring for 30min, increasing the rotating speed to 2000rpm, continuously stirring for 20min, cooling to room temperature, and filtering by 400-mesh filter paper to obtain paraffin particles containing silicon dioxide;

then dispersing the obtained paraffin particles containing the silicon dioxide in a second container filled with 100g of ethanol at room temperature and at a stirring speed of 250rpm, then adding 10g of water, 5g of ammonia water and 5g of 3- (2, 3-epoxypropoxy) propyltrimethoxysilane (A187), continuing stirring for 3 hours, then heating to 90 ℃ and preserving the temperature for 1 hour, then cooling to room temperature, and then centrifuging to obtain the paraffin particles containing the modified silicon dioxide;

dispersing the obtained modified silica-containing paraffin particles in 200g of chloroform at room temperature and at a stirring speed of 250rpm, stirring for 1h, centrifuging to remove the chloroform to obtain Janus silica nanoparticles, and finally ultrasonically dispersing the obtained Janus silica nanoparticles in 400g of water to form Janus silica nanoparticle aqueous dispersion;

(3) preparation of silicon dioxide composite acrylic acid/epoxy water-based resin

Heating the acrylic acid epoxy hybrid prepared in the step (2) to 60 ℃, increasing the rotating speed to 2000rpm, beginning to dropwise add 10g of N, N-dimethylethanolamine aqueous solution (the mass fraction of the N, N-dimethylethanolamine aqueous solution is between 50%), then dropwise add 55g of Janus silicon dioxide aqueous dispersion prepared in the step (1), wherein the dropwise add time is 90min, and then increasing the rotating speed to 3000 rpm; and (2) continuing to drop 30g of Janus silicon dioxide aqueous dispersion prepared in the step (1), then reducing the rotating speed to 2000rpm, and continuing to stir for 30min to obtain the silicon dioxide composite acrylic acid/epoxy waterborne resin.

The synthesis schematic diagrams of the steps (1), (2) and (3) are shown in figure 1.

The resins prepared in examples 1-3 were prepared into silica-containing composite acrylic/epoxy waterborne resin coatings.

Example 4

The main difference between example 4 and example 3 is that the aqueous dispersion of Janus-type silica particles in step (2) has a Janus-type silica particle content of 20% by mass; the others are unchanged.

Comparative example 1

The main difference between comparative example 1 and example 3 is the elimination of step (1) — the acrylic/epoxy intermediate in step (1) — is replaced by 5g of styrene +5g of butyl acrylate +0.5g of methacrylic acid +4.5g of propylene glycol butyl ether, the other steps remaining unchanged.

Comparative example 2

Comparative example 2 differs from example 3 in that in step (3) no Janus-containing silica dispersion is used, but water is used directly instead of the aqueous Janus-type silica particle dispersion.

The above examples 1-4 and comparative examples 1 and 2 were formulated into coatings according to the following composition:

the silicon dioxide-containing composite acrylic acid/epoxy water-based resin coating is prepared from the following components in percentage by mass:

60 parts of the resin of examples 1 to 4 or comparative example 1 or 2

The prepared coating is sprayed on a cold-rolled steel plate, the thickness of the wet film is controlled to be 200 mu m, the cold-rolled steel plate is baked at 80 ℃ for 30min to be cured and used for performance test, and the results are shown in Table 1.

As can be seen from Table 1, the paint films of examples 1-4 are superior in appearance, hardness, gloss, adhesion, flexibility, water resistance, resistance to artificial aging, salt spray resistance and heat storage stability, comparative example 2 is NG in heat storage stability, and comparative example 1 is significantly inferior to example 3 in gloss, water resistance and salt spray resistance.

The properties of the paint plaques prepared from the resins of examples 1 to 4 and comparative examples 1-2 are shown in the following table:

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