阅读说明：本技术 一种聚酯改性丙烯酸二级分散体的制备方法及其应用 (Preparation method and application of polyester modified acrylic acid secondary dispersion ) 是由 陈唯 何新华 冯煜皓 刘战 杨义博 于 2021-07-05 设计创作，主要内容包括：本发明公开了一种聚酯改性丙烯酸二级分散体的制备方法及其应用。一种聚酯改性丙烯酸二级分散体的制备方法,包括以下步骤：S1.将甲基丙烯酸缩水甘油酯滴加至端羧基聚酯树脂中,反应后,得端双键聚酯树脂；S2.使端双键聚酯树脂与不饱和类单体发生共聚反应；S3.将步骤S2所得混合物与亲水性的丙烯酸类单体反应,得聚酯改性丙烯酸树脂；S4.向步骤S3所得混合物中加入中和剂和水。本发明提供的聚酯改性丙烯酸二级分散体的制备方法,通过调整聚酯树脂与丙烯酸树脂共聚的位点,降低了所得聚酯改性丙烯酸树脂的粘度,进而避免了树脂聚合过程中出现的凝胶问题。(The invention discloses a preparation method and application of a polyester modified acrylic acid secondary dispersion. A preparation method of a polyester modified acrylic acid secondary dispersion comprises the following steps: s1, dripping glycidyl methacrylate into carboxyl-terminated polyester resin, and reacting to obtain double-bond-terminated polyester resin; s2, carrying out copolymerization reaction on the terminal double-bond polyester resin and an unsaturated monomer; s3, reacting the mixture obtained in the step S2 with a hydrophilic acrylic monomer to obtain polyester modified acrylic resin; s4, adding a neutralizing agent and water into the mixture obtained in the step S3. According to the preparation method of the polyester modified acrylic acid secondary dispersion, provided by the invention, the copolymerization site of the polyester resin and the acrylic resin is adjusted, so that the viscosity of the obtained polyester modified acrylic resin is reduced, and the problem of gel in the resin polymerization process is further avoided.)

1. The preparation method of the polyester modified acrylic acid secondary dispersion is characterized by comprising the following steps:

s1, dripping glycidyl methacrylate into carboxyl-terminated polyester resin, and reacting to obtain double-bond-terminated polyester resin;

s2, carrying out copolymerization reaction on the double-bond-terminated polyester resin and an unsaturated monomer;

s3, reacting the mixture obtained in the step S2 with a hydrophilic acrylic monomer to obtain polyester modified acrylic resin;

s4, adding a neutralizing agent and water into the polyester modified acrylate obtained in the step S3.

2. The method according to claim 1, wherein in step S1, the carboxyl-terminated polyester resin has an acid value of 10 to 30 mgKOH/g; preferably, the acid value of the terminal double-bond polyester resin is 1-3 mgKOH/g.

3. The method according to claim 1, wherein in step S2, the unsaturated monomer includes at least one of styrene, methyl methacrylate, isobornyl methacrylate, butyl acrylate, isooctyl acrylate, butyl methacrylate, hydroxyethyl methacrylate, and hydroxypropyl methacrylate.

4. The method according to claim 1, wherein in step S2, the mass of the double-bond-terminated polyester resin accounts for 10-20% of the mass of the unsaturated monomer.

5. The method according to claim 1, wherein in step S2, the copolymerization is initiated with an initiator; preferably, the copolymerization reaction is carried out by mixing the initiator, the double-bond-terminated polyester resin and the unsaturated monomer and then dropping the mixture into a hot organic solvent.

6. The method according to claim 5, wherein the temperature of the hot organic solvent is 120 to 150 ℃.

7. The method according to claim 1, wherein in step S3, the acrylic monomer includes at least one of acrylic acid and methacrylic acid.

8. The method according to claim 1, wherein in step S4, the neutralizing agent is at least one of an organic amine and ammonia water; preferably, the organic amine is at least one of triethylamine and N, N-dimethylethanolamine.

9. The method according to claim 1, wherein in step S4, the polyester-modified acrylic resin is added in an amount of 44 to 50 parts by weight, the neutralizing agent is added in an amount of 0.6 to 2 parts by weight, and the water is added in an amount of 48 to 55 parts by weight; preferably, the adding time of the water is 0.5-1 h; preferably, the temperature of the water is 60-90 ℃ in the water adding process.

10. An aqueous coating, characterized in that the raw materials for preparation comprise the polyester modified acrylic acid secondary dispersion prepared by the preparation method of any one of claims 1 to 9.

Technical Field

The invention belongs to the technical field of resin, and particularly relates to a preparation method and application of a polyester modified acrylic acid secondary dispersion.

Background

Resins commonly used in coatings include polyester resins and acrylic resins. The polyester resin has the characteristics of good coloring performance, high wetting fullness, good distinctness of image and the like, and can generally improve the decorative aesthetic property of the finish paint after being applied to the finish paint; however, polyester resins are not good in weather resistance, are easily hydrolyzed, and are difficult to exert their effects in aqueous coating materials. The acrylic resin has the advantages of good water resistance and good weather resistance, but has poor flexibility and poor wettability to pigments and fillers. Therefore, if the advantages of both resins can be fully integrated, a coating resin with excellent properties will be obtained.

In the industry, polyester and acrylic resins are usually integrated by both physical mixing and chemical modification. The physical mixing method is to uniformly mix the two resins in a mechanical stirring manner, and the method is simple and convenient, but because the compatibility of the two resins of polyester and acrylic acid is poor, the storability of the mixed resin is poor, and further, the coating containing the mixed resin is easy to lose gloss. The chemical modification method is the most widely used method in the industry, wherein the chemical modification method also comprises copolymerization of acrylate monomers and unsaturated polyesters, and polycondensation of acrylic resins and polyhydric alcohols and polybasic acids. Although the chemical modification method can ensure that the two have good compatibility and can solve the problem of coating light loss, the resin prepared by the chemical modification method usually has very high viscosity, and the resin polymerization process is easy to generate gel and the like.

Disclosure of Invention

The present invention is directed to solving at least one of the problems of the prior art described above. Therefore, the invention provides a preparation method of the polyester modified acrylic acid secondary dispersion, which reduces the viscosity of the obtained polyester modified acrylic acid secondary dispersion by adjusting the copolymerization site of the polyester resin and the acrylic resin, thereby avoiding the problem of gelation in the preparation and application processes.

The invention also provides a water-based paint containing the polyester modified acrylic acid secondary dispersion obtained by the preparation method.

According to one aspect of the present invention, a method for preparing a polyester modified acrylic secondary dispersion is provided, comprising the steps of:

s1, dripping glycidyl methacrylate into carboxyl-terminated polyester resin, and reacting to obtain double-bond-terminated polyester resin;

s2, carrying out copolymerization reaction on the double-bond-terminated polyester resin and an unsaturated monomer;

s3, reacting the mixture obtained in the step S2 with a hydrophilic acrylic monomer to obtain polyester modified acrylic resin;

s4, adding a neutralizing agent and water into the polyester modified acrylic resin obtained in the step S3.

According to a preferred embodiment of the present invention, at least the following advantages are provided:

(1) in a common method for integrating polyester resin and acrylic resin by a chemical modification method, the bonding site of the polyester resin and the acrylic resin is difficult to control, if the bonding site is in the middle of a polyester resin molecular chain, every polyester resin molecule is introduced, namely two branched chains are introduced on the acrylic resin molecular chain, so that a branched molecular chain is formed, the polyester modified acrylic resin with a branched structure has high viscosity, and the gel phenomenon is easy to occur in the preparation process;

according to the preparation method provided by the invention, the carboxyl-terminated polyester resin is used as a raw material to generate the double-bond-terminated polyester resin, and the end part of the polyester resin is used as a binding site to be bound with the acrylic resin.

(2) In the preparation method provided by the invention, in step S3, the reaction with hydrophilic acrylic monomers is specially designed, so that the hydrophilicity of the obtained polyester modified acrylic resin is further improved, and the polyester modified acrylic resin is more suitable for preparing water-based coatings.

(3) The aqueous secondary dispersion prepared by the preparation method provided by the invention has high solid content, can keep lower viscosity, and has low content of organic solvent, so that the VOC content is low, and the preparation method is environment-friendly.

In some embodiments of the invention, in step S1, the carboxyl-terminated polyester resin is at least one from commercially available or from laboratory homemade sources.

In some embodiments of the present invention, the carboxyl-terminated polyester resin is prepared by a method comprising the steps of:

A1. carrying out esterification reaction on the polybasic alcohol and the polybasic acid to obtain polyester resin;

A2. and D, adding an acidolysis agent into the mixture obtained in the step A1, and continuing to react to obtain the carboxyl-terminated polyester resin.

In some embodiments of the invention, in step a1, the polyol comprises at least one of ethylene glycol, propylene glycol, hexylene glycol, trimethylolpropane, neopentyl glycol, and ethylbutylpropanediol.

In some embodiments of the present invention, in the step A1, the polyol is added in an amount of 30 to 50 parts by weight.

In some embodiments of the invention, in step a1, the polyacid comprises at least one of isophthalic acid, terephthalic acid, adipic acid, and 1, 4-cyclohexanedicarboxylic acid.

In some embodiments of the present invention, in the step a1, the polybasic acid is added in an amount of 40 to 60 parts by weight.

In some embodiments of the present invention, in step a1, the esterification reaction is carried out with the aid of a catalyst.

In some embodiments of the present invention, the catalyst for the esterification reaction is an organotin catalyst.

In some embodiments of the present invention, the organotin catalyst is monobutyltin oxide.

In some embodiments of the present invention, the catalyst is added in an amount of 0.1 to 0.5 parts by weight.

In some embodiments of the invention, in step a1, the esterification reaction starts at a temperature of 170 ℃.

The starting temperature was 170 ℃, meaning that the ramp rate was not controlled until 170 ℃.

In some embodiments of the present invention, in step A1, the temperature rise rate of the esterification reaction is 10 ℃/h.

In some embodiments of the present invention, in step a1, the isothermal temperature for the esterification reaction is 230 ℃.

In some embodiments of the present invention, in the step a1, the constant temperature time of the esterification reaction is 1 to 3 hours.

In some embodiments of the present invention, step a1, the esterification reaction further comprises vacuum dehydration.

In some embodiments of the invention, the vacuum dehydration lasts for 1-3 hours.

The vacuum dehydration has the function of distilling the product and promoting the forward progress of the esterification reaction.

In some embodiments of the present invention, in step A1, the polyester resin has an acid number of 5mgKOH/g or less.

In some preferred embodiments of the present invention, in the step A1, the acid value of the polyester resin is 1 to 5 mgKOH/g.

In some embodiments of the invention, in step a2, the constant temperature in step a1 is maintained.

In some embodiments of the present invention, in step a2, the acid hydrolysis agent comprises at least one of trimellitic anhydride, isophthalic acid, and adipic acid.

In some embodiments of the present invention, in the step a2, the acid hydrolysis agent is added in an amount of 1 to 5 parts by weight.

In some embodiments of the present invention, in step A2, the reaction is continued, and at the end, the acid value of the mixture is 10 to 30 mgKOH/g.

The preparation method of the carboxyl-terminated polyester resin provided by the invention is synthesized by bulk polycondensation, and compared with esterification reaction in a solution, the preparation method is simpler and more environment-friendly.

In some embodiments of the present invention, in step S1, the glycidyl methacrylate is added in an amount of 2 to 8 parts by weight.

In some embodiments of the present invention, in step S1, the carboxyl-terminated polyester resin has an acid value of 10 to 30 mgKOH/g.

In some embodiments of the present invention, in step S1, the dropping is performed for 0.5 to 1 hour.

In some preferred embodiments of the present invention, in step S1, the reaction time is 0.5 h.

In some embodiments of the present invention, in step S1, the temperature of the dropping and the reaction is 140 to 180 ℃.

In some embodiments of the present invention, in step S1, the terminal double bond polyester resin has an acid value of 1 to 3 mgKOH/g.

In some embodiments of the present invention, in step S2, the unsaturated monomer includes at least one of styrene, methyl methacrylate, isobornyl methacrylate, butyl acrylate, isooctyl acrylate, butyl methacrylate, hydroxyethyl methacrylate, and hydroxypropyl methacrylate.

In some embodiments of the present invention, in step S2, the mass of the terminal double bond polyester resin accounts for 10 to 20% of the mass of the unsaturated monomer.

When the addition amount of the polyester resin with the terminal double bonds is within the range, the polyester modified acrylic secondary dispersion does not generate a gel phenomenon in the preparation process, and simultaneously can embody the performance advantages brought by the polyester resin in the polyester modified acrylic secondary dispersion.

In some embodiments of the invention, in step S2, the copolymerization reaction is initiated with an initiator.

In some embodiments of the present invention, in step S2, the copolymerization reaction is performed by mixing the initiator, the terminal double bond polyester resin and the unsaturated monomer, and then dropping the mixture into the hot organic solvent.

In some embodiments of the present invention, the temperature of the hot organic solvent is 120 to 150 ℃.

In some preferred embodiments of the present invention, in step S2, the copolymerization reaction comprises the following steps:

s2a, heating an organic solvent to 120-150 ℃ to obtain the hot organic solvent;

s2b, mixing the initiator, the double-bond-terminated polyester resin and the unsaturated monomer, then dropwise adding the mixture into the hot organic solvent obtained in the step S2a, and continuing to react.

In some embodiments of the present invention, in step S2a, the amount of the hot organic solvent is 1 to 20 parts by weight.

In some embodiments of the present invention, in step S2b, the amount of the double-bond-terminated polyester resin is 5 to 14 parts by weight.

In some embodiments of the present invention, in step S2b, the initiator is used in an amount of 2 to 4 parts by weight.

In some embodiments of the invention, in step S2b, the dropping is performed for 3 to 5 hours.

In some embodiments of the present invention, in step S2b, the reaction is continued for 0.5 to 1 hour.

In some embodiments of the invention, the organic solvent is an alcohol ether based solvent.

In some preferred embodiments of the present invention, the organic solvent comprises at least one of ethylene glycol butyl ether, propylene glycol butyl ether, dipropylene glycol methyl ether, and dipropylene glycol butyl ether.

In some embodiments of the invention, in step S3, the acrylic monomer comprises at least one of acrylic acid and methacrylic acid.

In some embodiments of the present invention, in step S3, the acrylic monomer is used in an amount of 10 to 15 parts by weight.

In some embodiments of the invention, in step S3, the reaction is initiated with an initiator.

In some embodiments of the present invention, in step S3, the reaction is performed by: mixing the hydrophilic methacrylic acid monomer with the initiator, and then dropwise adding the mixture into the mixture obtained in the step S2; the dripping time is 0.5-1 h; and after the dropwise addition is finished, continuously preserving the heat for 2-5 hours.

In some embodiments of the present invention, the initiator is used in combination with the hydrophilic methacrylic monomer in an amount of 0.3 to 1 part by weight.

In some embodiments of the present invention, the initiator for initiating the reaction in step S2 may be the same as or different from the initiator for initiating the reaction in step S3.

In some embodiments of the invention, the initiator comprises at least one of benzoyl peroxide, t-amyl peroxyacetate, and t-butyl peroxytrimethylhexanoate.

In some embodiments of the present invention, in step S4, the neutralizing agent and the water are sequentially added to the polyester-modified acrylic resin.

In some embodiments of the invention, in step S4, the neutralizing agent is at least one of an organic amine and ammonia water.

In some preferred embodiments of the present invention, the organic amine is at least one of triethylamine and N, N-dimethylethanolamine.

In some further preferred embodiments of the present invention, the neutralizing agent is N, N-dimethylethanolamine.

In some embodiments of the invention, the neutralization coefficient is 0.5 to 0.9.

The neutralization coefficient refers to the ratio of the addition amount of the neutralizing agent to the acid equivalent of the polyester modified acrylic resin.

In some embodiments of the present invention, the step S4 further includes performing aging after the neutralizing agent is added, where the aging is performed for 10 to 30 min.

In some embodiments of the present invention, in step S4, the water is added for 0.5 to 1 hour.

In some embodiments of the present invention, in step S4, the water is added with water, and the temperature of the water is 60 to 90 ℃.

In some embodiments of the invention, the step S4 further includes continuing stirring for 0.5 to 1 hour after the water is added.

In some embodiments of the present invention, in step S4, the polyester modified acrylic resin is added in an amount of 44 to 50 parts by weight, and the neutralizing agent is added in an amount of 0.6 to 2 parts by weight; the addition amount of the water is 48-55 parts.

In some embodiments of the invention, the preparation method is performed in a reaction kettle.

In some embodiments of the invention, the solid content in the polyester modified acrylic secondary dispersion obtained by the preparation method is 44-50%.

In some embodiments of the invention, the polyester modified acrylic secondary dispersion obtained by the preparation method has a particle size D50 of 100-140 nm.

In some embodiments of the invention, the polyester modified acrylic secondary dispersion obtained by the preparation method has a hydroxyl content of 1-3.5%.

According to still another aspect of the present invention, there is provided an aqueous coating material prepared from an aqueous secondary dispersion prepared by the above-mentioned preparation method.

The water-based paint according to a preferred embodiment of the invention has at least the following beneficial effects:

(1) the water-based paint containing the water-based secondary dispersion provided by the invention can obtain high gloss and high fullness, and particularly, the 60-degree gloss is more than 90 percent, the 20-degree gloss is more than 80 percent, and the distinctness of image is strong.

(2) In the water-based paint provided by the invention, the water-based secondary dispersion prepared by the invention can be matched with isocyanate to form water-based bi-component polyurethane resin; or can be matched with amino resin to prepare water-based amino baking paint;

in conclusion, the water-based secondary dispersion provided by the invention has wide application range and can form various water-based coatings.

(3) The water-based paint provided by the invention can meet the field of automobile paint, wood paint and the like with high decorative requirements.

The water used in the present invention is at least one of deionized water and ultrapure water, unless otherwise specified.

Detailed Description

The concept and technical effects of the present invention will be clearly and completely described below in conjunction with the embodiments to fully understand the objects, features and effects of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and those skilled in the art can obtain other embodiments without inventive effort based on the embodiments of the present invention, and all embodiments are within the protection scope of the present invention.

In the description of the present invention, the meaning of a plurality is one or more, the meaning of a plurality is two or more, and the above, below, exceeding, etc. are understood as excluding the present numbers, and the above, below, within, etc. are understood as including the present numbers. If the first and second are described for the purpose of distinguishing technical features, they are not to be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated or implicitly indicating the precedence of the technical features indicated.

Example 1

This example prepares an aqueous secondary dispersion by the specific process of:

B1. preparation of carboxyl-terminated polyester resin:

preparing materials: 35g of neopentyl glycol, 5g of ethylene glycol, 5g of trimethylolpropane, 5g of ethylbutylpropanediol, 30g of isophthalic acid, 10g of adipic acid, 0.2g of monobutyltin oxide (catalyst) are added to the reaction vessel;

reaction: heating from 170 ℃ according to a program, heating to 230 ℃ according to a heating rate of 10 ℃/h, preserving heat for 1h, and then vacuumizing for 1h until the acid value of materials in the kettle is lower than 5 mgKOH/g; adding 4g of trimellitic anhydride (acidolysis agent) and continuing to preserve heat until the acid value of the material is 30mgKOH/g, and cooling to 160 ℃ to obtain carboxyl-terminated polyester resin;

B2. preparing the polyester resin with terminal double bonds:

dripping 6g of Glycidyl Methacrylate (GMA) into the mixture obtained in the step B1 for 0.5h, then keeping the temperature for 0.5h until the acid value is lower than 3mgKOH/g, stopping reaction and discharging to obtain the terminal double bond polyester resin;

B3. preparation of polyester modified acrylic resin:

adding 5g of ethylene glycol butyl ether (organic solvent) into a reaction kettle, heating to 130 ℃, and then dropwise adding a mixture, wherein the mixture consists of 8g of the double-bond-terminated polyester resin obtained in the step B2, 30g of methyl methacrylate, 20g of isooctyl acrylate, 9g of styrene, 11g of hydroxyethyl methacrylate and 4g of tert-amyl peroxyacetate (initiator 1); the dripping time is 3h, and the temperature is kept for 0.5h after the dripping is finished;

then, dropwise adding a mixed solution of 12g of methacrylic acid and 0.8g of benzoyl peroxide (initiator 2) for 1h, and then, preserving heat for 2h after dropwise adding to obtain polyester modified acrylic resin;

B4. preparation of aqueous secondary dispersion:

adding 0.6g of N, N-dimethylethanolamine (neutralizing agent) into 50g of the polyester modified acrylic resin prepared in the step B3 at 90 ℃, curing for 10min, and then dripping 49.4g of deionized water for 0.5h at 80 ℃; and continuously stirring for 0.5h after the dripping is finished, thus obtaining the aqueous secondary dispersion.

Example 2

This example prepares an aqueous secondary dispersion by the specific process of:

B1. preparation of carboxyl-terminated polyester resin:

preparing materials: into the reaction vessel were charged 30g of neopentyl glycol, 9g of propylene glycol, 2g of trimethylolpropane, 2g of ethylbutylpropanediol, 25g of isophthalic acid, 15g of adipic acid and 0.2g of monobutyltin oxide (catalyst);

reaction: heating from 170 ℃ according to a program, heating to 230 ℃ according to a heating rate of 10 ℃/h, preserving heat for 1h, and then vacuumizing for 1h until the acid value of materials in the kettle is lower than 5 mgKOH/g; adding 5g of isophthalic acid (acidolysis agent) and keeping the temperature until the acid value of the material is 25mgKOH/g, and cooling to 160 ℃ to obtain carboxyl-terminated polyester resin;

B2. preparing the polyester resin with terminal double bonds:

dripping 4g of Glycidyl Methacrylate (GMA) into the mixture obtained in the step B1 for 0.5h, then keeping the temperature for 0.5h until the acid value is lower than 3mgKOH/g, stopping reaction and discharging to obtain the terminal double bond polyester resin;

B3. preparation of polyester modified acrylic resin:

adding 14g of propylene glycol butyl ether (organic solvent) into a reaction kettle, heating to 130 ℃, and then dropwise adding a mixture, wherein the mixture consists of 12g of the double-bond-terminated polyester resin obtained in the step B2, 30g of butyl acrylate, 25g of isobornyl methacrylate, 2g of styrene, 4g of hydroxyethyl methacrylate and 2g of tert-butyl peroxytrimethylhexanoate (initiator 1); the dripping time is 3h, and the temperature is kept for 0.5h after the dripping is finished;

then, dropwise adding a mixed solution of 10g of methacrylic acid and 0.6g of benzoyl peroxide (initiator 2) for 1h, and then, preserving heat for 2h after dropwise adding to obtain polyester modified acrylic resin;

B4. preparation of aqueous secondary dispersion:

adding 45g of the polyester modified acrylic resin prepared in the step B3 into 0.5g N of N-dimethylethanolamine (neutralizing agent) at the temperature of 80 ℃, curing for 10min, and then dripping 54.5g of deionized water for 0.5h at the temperature of 80 ℃; and continuously stirring for 0.5h after the dripping is finished, thus obtaining the aqueous secondary dispersion.

Example 3

This example prepares an aqueous secondary dispersion by the specific process of:

B1. preparation of carboxyl-terminated polyester resin:

preparing materials: 38g of neopentyl glycol, 3g of hexanediol, 4g of trimethylolpropane, 5g of ethylbutylpropanediol, 20g of terephthalic acid, 15g of adipic acid, 10g of 1, 4-cyclohexanedicarboxylic acid and 0.3g of monobutyltin oxide (catalyst) were charged to the reaction vessel;

reaction: heating from 170 ℃ according to a program, heating to 230 ℃ according to a heating rate of 10 ℃/h, preserving heat for 1h, and then vacuumizing for 1h until the acid value of materials in the kettle is lower than 5 mgKOH/g; adding 3g of meta-phthalic acid (acidolysis agent) and keeping the temperature until the acid value of the material is 20mgKOH/g, and cooling to 160 ℃ to obtain carboxyl-terminated polyester resin;

B2. preparing the polyester resin with terminal double bonds:

dripping 2g of Glycidyl Methacrylate (GMA) into the mixture obtained in the step B1 for 0.5h, then keeping the temperature for 0.5h until the acid value is lower than 3mgKOH/g, stopping reaction and discharging to obtain the terminal double bond polyester resin;

B3. preparation of polyester modified acrylic resin:

adding 15g of dipropylene glycol butyl ether (organic solvent) into a reaction kettle, heating to 130 ℃, and then dropwise adding a mixture, wherein 9g of the mixture consists of the double-bond-terminated polyester resin obtained in the step B2, 20g of butyl acrylate, 9g of methyl methacrylate, 15g of isobornyl methacrylate, 17g of hydroxypropyl methacrylate and 2g of tert-butyl peroxytrimethylhexanoate (initiator 1); the dripping time is 3h, and the temperature is kept for 0.5h after the dripping is finished;

then, dropwise adding a mixed solution of 10g of methacrylic acid and 0.6g of benzoyl peroxide (initiator 2) for 1h, and then, preserving heat for 2h after dropwise adding to obtain polyester modified acrylic resin;

B4. preparation of aqueous secondary dispersion:

adding 1g N N-dimethylethanolamine (neutralizer) into 46g of the polyester modified acrylic resin prepared in the step B3 at 80 ℃, curing for 10min, and then dripping 53g of deionized water for 0.5h at 80 ℃; and continuously stirring for 0.5h after the dripping is finished, thus obtaining the aqueous secondary dispersion.

Comparative example 1

This comparative example prepared an aqueous secondary dispersion which differed from example 3 in that:

(1) does not include steps B1-B2;

(2) step B3, excluding 9g of the double bond-terminated polyester resin obtained in step B2;

(3) in step B4, the amount of polyester-modified acrylic resin prepared in step B3 was 45g, not 46 g; the deionized water used was 54g instead of 53 g.

Comparative example 2

This comparative example prepared an aqueous secondary dispersion which differed from example 1 in that:

(1) in step B3, 4g of the double bond terminated polyester resin obtained in step B2 was copolymerized with an unsaturated monomer under the same conditions as in example 1.

Test examples

This test example tests the performance of the aqueous secondary dispersions prepared in the examples and comparative examples.

Firstly, the parameters of the aqueous secondary dispersions obtained in examples 1 to 3 and comparative examples 1 to 2 were characterized, and the characterization results are shown in table 1.

TABLE 1 parameters of the aqueous secondary dispersions obtained in examples 1 to 3 and comparative examples 1 to 2

Then preparing a white paint from the aqueous secondary dispersion obtained in the examples 1-3 and the comparative example 1 according to the mixture ratio shown in the table 2, wherein the secondary dispersion in the table 2 is obtained from the examples 1-3 or the comparative examples 1-2; the resulting white paint was then tested for performance parameters, the test methods and results are shown in table 3.

Table 3 Properties of white paints including the aqueous secondary dispersions obtained in examples 1 to 3 and comparative examples 1 to 2

Example 1

Example 2

Example 3

Comparative example 1

Comparative example 2

Test method

20 degree gloss

83％

81％

84％

72％

72％

GB/T9754

60 degree gloss

95％

93％

96％

86％

86％

GB/T9754

Adhesion force

Level 0

Level 0

Level 0

Level 1

Level 1

GB/T9286

Hardness of pencil

H

H

H

H

H

BG/T6739

The results in Table 3 show that even though the performances of the aqueous secondary dispersions obtained in the examples and the comparative examples are equivalent, the gloss, the adhesion and the pencil hardness of the white paint prepared from the aqueous secondary dispersion are all excellent within the range provided by the invention (examples 1-3), and if the aqueous secondary dispersion does not contain the polyester resin with the terminal double bonds (comparative example 1) or the amount of the polyester with the terminal double bonds is small (comparative example 2), the gloss and the adhesion of the obtained white paint are reduced to a certain extent.

The embodiments of the present invention have been described in detail, but the present invention is not limited to the embodiments, and various changes can be made without departing from the gist of the present invention within the knowledge of those skilled in the art. Furthermore, the embodiments of the present invention and the features of the embodiments may be combined with each other without conflict.