Preparation process and application of carboxyl hyperbranched polymer modified coating

Abstract

The invention relates to the technical field of acrylic resin coatings, and discloses a preparation process and application of a carboxyl hyperbranched polymer modified coating, glycidyl acrylate-based acrylic resin is prepared by taking methyl methacrylate, butyl acrylate, glycidyl methacrylate and the like as polymeric monomers, and the carboxyl hyperbranched polymer modified coating is prepared by taking the glycidyl acrylate-based acrylic resin as an initiator. The carboxyl hyperbranched polymer is used for modifying the acrylic resin, and in the curing process, carboxyl of the hyperbranched polymer can be subjected to a ring-opening reaction with epoxy groups of the acrylic resin, so that the hyperbranched polymer and the acrylic resin are subjected to cross-linking curing, curing of the acrylic resin is promoted, and the surface drying time is shortened; the hyperbranched polymer and the acrylic resin form a temperature-stable cross-linked network, so that the cross-linking degree of an acrylic resin molecular chain is increased, the hardness and adhesive force of a paint film are improved, and meanwhile, corrosive media such as water molecules and salt are prevented from entering the paint film, so that the water resistance and salt water resistance of the paint film are improved.

Description

Technical Field

[0001] The invention relates to the technical field of acrylic resin coatings, in particular to a preparation process and application of a carboxyl hyperbranched polymer modified coating. Background Art

[0002] Acrylic resin coatings are widely used in the automotive, electrical, machinery, and construction industries due to their advantages of ease of construction, recoating, and rework. However, traditional acrylic resin coatings suffer from issues such as saltwater resistance and poor hardness, which hinder their application.

[0003] The development of high-performance acrylic resin coatings is of great significance. Patent CN102911371B discloses a vacuum melt polycondensation method to obtain a polyester-type hyperbranched polymer with terminal hydroxyl groups, which is then esterified with a carboxyl-containing acrylic resin to produce a hyperbranched polyester-modified acrylic resin. This method reduces the curing time of the coating and produces a high-solids, low-viscosity hyperbranched polyester-modified acrylic resin. However, this method does not address the problems of saltwater resistance and low hardness of the acrylic resin coating.

[0004] Hyperbranched polymers are a class of highly branched three-dimensional macromolecules that can be used as functional materials and have a wide range of applications in coatings, water pollution treatment, and drug carriers. This invention aims to prepare a carboxyl hyperbranched polymer that solves the problems of poor salt water resistance and low hardness of acrylic resin coatings. Summary of the Invention

[0005] The technical problem solved by the present invention is to provide a preparation process and application of a carboxyl hyperbranched polymer modified coating, thereby solving the problems of poor salt water resistance and low hardness of acrylic resin coatings.

[0006] The technical solution of the present invention is: A preparation process for a carboxyl hyperbranched polymer modified coating comprises the following steps: Step S1: add m-dipropyleneoxyphenyliminethioglycolic acid intermediate and N,N-dimethylacetamide into a flask, introduce nitrogen, and dropwise add catalyst triethylamine. After the reaction, methanol is added to the solution to precipitate, which is filtered, washed with ethanol, and dried to obtain a carboxyl hyperbranched polymer.

[0007] Step S2: adding a carboxyl hyperbranched polymer, a defoamer, a leveling agent, and a film-forming aid to an emulsion of glycidyl acrylate-based acrylic resin, and dispersing the mixture at high speed to obtain a carboxyl hyperbranched polymer-modified coating.

[0008] Preferably, the amount of triethylamine used in step S1 is 0.8-2% of the mass of the m-dipropyleneoxyphenyliminethioglycolic acid intermediate.

[0009] Preferably, the reaction in step S1 is stirred at room temperature for 12-36 h.

[0010] Preferably, in step S2, the carboxyl hyperbranched polymer is 1-10% by mass of the glycidyl acrylate-based acrylic resin.

[0011] Preferably, the preparation process of the m-dipropyleneoxyphenylimine thioglycolic acid intermediate comprises the following steps: Step S3: Add toluene, 3,5-dihydroxybenzaldehyde, and 2-bromopropylene to a flask, stir to dissolve, add a catalyst tetrabutylammonium bromide, and an aqueous solution of sodium hydroxide, react at 40-60° C. for 12-24 hours, add ethyl acetate for extraction, separate, and concentrate the organic phase under reduced pressure, and wash with petroleum ether to obtain a 3,5-di(propyleneoxy)benzaldehyde intermediate.

[0012] Step S4: Add ethanol, 3,5-di(propyleneoxy)benzaldehyde intermediate, and cysteine to a flask, react at 65-80° C. for 6-24 h, cool, add sodium borohydride for reduction, concentrate to remove ethanol after the reaction, add 5-8% by mass acetic acid solution and dichloromethane for extraction, separate, concentrate the organic phase under reduced pressure, and wash with petroleum ether to obtain a dipropyleneoxyphenylimine thioglycolic acid intermediate; the reaction formula is:

[0013] Preferably, in step S3, the molar ratio of 3,5-dihydroxybenzaldehyde, 2-bromopropylene, tetrabutylammonium bromide, and sodium hydroxide is 1:(2.8-3.5):(0.01-0.015):(2.5-3.5).

[0014] Preferably, in step S3, the molar ratio of the 3,5-bis(propyleneoxy)benzaldehyde intermediate to cysteine is 1:(0.8-1.4).

[0015] Preferably, the preparation process of the emulsion of glycidyl acrylate-based acrylic resin in step S2 comprises the following steps: adding water, sodium dodecylsulfonate, methyl methacrylate, butyl acrylate, glycidyl methacrylate, and hydroxyethyl acrylate to a reaction flask, stirring the solvent, and then dropwise adding an aqueous solution of ammonium persulfate, reacting at 60-70° C. for 2-3 hours, and cooling to obtain the emulsion of glycidyl acrylate-based acrylic resin.

[0016] The beneficial technical effects of the present invention are: A novel AB2-type monomer dipropylene glycol imine thioglycolic acid intermediate was prepared using 3,5-dihydroxybenzaldehyde, 2-bromopropylene and cysteine as reactants. It contains two olefin groups and one thiol group. Using triethylamine as a catalyst, a thiol-olefin addition reaction occurred, and a novel carboxyl hyperbranched polymer was obtained through self-crosslinking polymerization.

[0017] A glycidyl methacrylate-based acrylic resin was prepared using methyl methacrylate, butyl acrylate, glycidyl methacrylate, etc. as polymerization monomers, and the acrylic resin was modified using a carboxyl hyperbranched polymer. During the curing process, the carboxyl groups of the hyperbranched polymer can undergo a ring-opening reaction with the epoxy groups of the acrylic resin, thereby cross-linking and curing the hyperbranched polymer and the acrylic resin, promoting the curing of the acrylic resin and reducing the surface drying time; the hyperbranched polymer and the acrylic resin form a temperature-stable cross-linked network, increasing the cross-linking degree of the acrylic resin molecular chain, improving the hardness and adhesion of the paint film, and at the same time hindering the entry of corrosive media such as water molecules and salt into the paint film, thereby improving the water resistance and salt water resistance of the paint film. DETAILED DESCRIPTION

[0018] The present invention will be described in detail below through examples. The examples described in the present invention are only some examples of the present invention, not all examples. All other examples obtained by persons of ordinary skill in the art based on the examples of the present invention without creative work are within the scope of protection of the present invention.

[0019] Example 1 Add 150 mL of toluene, 10 mmol of 3,5-dihydroxybenzaldehyde, and 28 mmol of 2-bromopropylene to a flask, stir to dissolve, and add 0.15 mmol of catalyst tetrabutylammonium bromide and 120 mL of an aqueous solution containing 35 mmol of sodium hydroxide. React at 50°C for 24 h, add ethyl acetate for extraction, separate, and concentrate the organic phase under reduced pressure. Wash with petroleum ether to obtain the intermediate 3,5-di(propyleneoxy)benzaldehyde.

[0020] 100 mL of ethanol, 20 mmol of the 3,5-bis(propyleneoxy)benzaldehyde intermediate, and 16 mmol of cysteine were added to a flask and reacted at 65°C for 12 h. After cooling, 40 mmol of sodium borohydride was added for reduction. After the reaction, the ethanol was removed by concentration, and 6% acetic acid solution and dichloromethane were added for extraction. After separation, the organic phase was concentrated under reduced pressure and washed with petroleum ether to obtain the dipropylene glycol imine thioglycolic acid intermediate.

[0021] 20 g of the m-dipropyleneoxyphenyliminethioglycolic acid intermediate and 300 mL of N,N-dimethylacetamide were added to a flask, nitrogen was introduced, and 0.4 g of triethylamine as a catalyst was added dropwise. The reaction was stirred at room temperature for 36 h. After the reaction, methanol was added to the solution to precipitate, which was filtered, washed with ethanol, and dried to obtain a carboxyl hyperbranched polymer.

[0022] To a reaction flask, 50 mL of water, 0.36 g of sodium dodecylsulfonate, 4.5 g of methyl methacrylate, 15 g of butyl acrylate, 1.2 g of glycidyl methacrylate, and 1.2 g of hydroxyethyl acrylate were added. After stirring the solvent, an aqueous solution of ammonium persulfate was added dropwise. The mixture was reacted at 60 °C for 3 h and cooled to obtain an emulsion of glycidyl acrylate-based acrylic resin.

[0023] A carboxyl hyperbranched polymer is added to an emulsion of a glycidyl acrylate-based acrylic resin, wherein the carboxyl hyperbranched polymer is 1% by mass of the glycidyl acrylate-based acrylic resin, the defoamer RP-6301 is 0.4%, the leveling agent PLP-650 is 0.1%, and the film-forming aid dipropylene glycol methyl ether is 2%. The mixture is dispersed at high speed to obtain a carboxyl hyperbranched polymer-modified coating.

[0024] Example 2 Add 200 mL of toluene, 10 mmol of 3,5-dihydroxybenzaldehyde, and 30 mmol of 2-bromopropylene to a flask, stir to dissolve, and add 0.12 mmol of catalyst tetrabutylammonium bromide and 120 mL of an aqueous solution containing 25 mmol of sodium hydroxide. React at 60°C for 18 h, add ethyl acetate for extraction, separate, and concentrate the organic phase under reduced pressure. Wash with petroleum ether to obtain the intermediate 3,5-di(propyleneoxy)benzaldehyde.

[0025] 200 mL of ethanol, 20 mmol of the 3,5-di(propyleneoxy)benzaldehyde intermediate, and 20 mmol of cysteine were added to a flask and reacted at 70°C for 18 h. After cooling, 40 mmol of sodium borohydride was added for reduction. After the reaction, the ethanol was removed by concentration, and 8% acetic acid solution and dichloromethane were added for extraction. After separation, the organic phase was concentrated under reduced pressure and washed with petroleum ether to obtain the dipropylene glycol imine thioglycolic acid intermediate.

[0026] 20 g of the m-dipropyleneoxyphenyliminethioacetic acid intermediate and 300 mL of N,N-dimethylacetamide were added to a flask, nitrogen was introduced, and 0.3 g of triethylamine as a catalyst was added dropwise. The reaction was stirred at room temperature for 36 h. After the reaction, methanol was added to the solution to precipitate, which was filtered, washed with ethanol, and dried to obtain a carboxyl hyperbranched polymer.

[0027] To a reaction flask, add 40 mL of water, 0.5 g of sodium dodecylsulfonate, 5.2 g of methyl methacrylate, 15 g of butyl acrylate, 1.2 g of glycidyl methacrylate, and 1 g of hydroxyethyl acrylate. After stirring the solvent, add dropwise an aqueous solution of ammonium persulfate. React at 60 °C for 3 h and cool to obtain an emulsion of glycidyl methacrylate-based acrylic resin.

[0028] A carboxyl hyperbranched polymer is added to an emulsion of a glycidyl acrylate-based acrylic resin, wherein the carboxyl hyperbranched polymer is 3% by mass of the glycidyl acrylate-based acrylic resin, a defoamer RP-6301 is 0.1%, a leveling agent PLP-650 is 0.3%, and a film-forming aid dipropylene glycol methyl ether is 3%. The mixture is dispersed at high speed to obtain a carboxyl hyperbranched polymer-modified coating.

[0029] Example 3 Add 200 mL of toluene, 10 mmol of 3,5-dihydroxybenzaldehyde, and 35 mmol of 2-bromopropylene to a flask, stir to dissolve, and add 0.12 mmol of catalyst tetrabutylammonium bromide and 150 mL of an aqueous solution containing 28 mmol of sodium hydroxide. React at 50°C for 18 hours, add ethyl acetate for extraction, separate, and concentrate the organic phase under reduced pressure. Wash with petroleum ether to obtain the intermediate 3,5-di(propyleneoxy)benzaldehyde.

[0030] 150 mL of ethanol, 20 mmol of the 3,5-di(propyleneoxy)benzaldehyde intermediate, and 28 mmol of cysteine were added to a flask and reacted at 80°C for 6 h. After cooling, 40 mmol of sodium borohydride was added for reduction. After the reaction, the ethanol was removed by concentration, and 8% acetic acid solution and dichloromethane were added for extraction. After separation, the organic phase was concentrated under reduced pressure and washed with petroleum ether to obtain the dipropylene glycol imine thioglycolic acid intermediate.

[0031] 20 g of the m-dipropyleneoxyphenyliminethioglycolic acid intermediate and 200 mL of N,N-dimethylacetamide were added to a flask, nitrogen was introduced, and 0.4 g of triethylamine as a catalyst was added dropwise. The reaction was stirred at room temperature for 36 h. After the reaction, methanol was added to the solution to precipitate, which was filtered, washed with ethanol, and dried to obtain a carboxyl hyperbranched polymer.

[0032] To a reaction flask, add 60 mL of water, 0.3 g of sodium dodecylsulfonate, 6 g of methyl methacrylate, 14 g of butyl acrylate, 1.4 g of glycidyl methacrylate, and 1.2 g of hydroxyethyl acrylate. After stirring the solvent, add an aqueous solution of ammonium persulfate dropwise. React at 60 °C for 3 h and cool to obtain an emulsion of glycidyl acrylate-based acrylic resin.

[0033] A carboxyl hyperbranched polymer is added to an emulsion of a glycidyl acrylate-based acrylic resin, wherein the carboxyl hyperbranched polymer accounts for 5% of the mass of the glycidyl acrylate-based acrylic resin, the defoamer RP-6301 accounts for 0.2%, the leveling agent PLP-650 accounts for 0.2%, and the film-forming aid dipropylene glycol methyl ether accounts for 3%. The mixture is dispersed at high speed to obtain a carboxyl hyperbranched polymer-modified coating.

[0034] Example 4 Add 150 mL of toluene, 10 mmol of 3,5-dihydroxybenzaldehyde, and 30 mmol of 2-bromopropylene to a flask, stir to dissolve, and add 0.1 mmol of catalyst tetrabutylammonium bromide and 100 mL of an aqueous solution containing 25 mmol of sodium hydroxide. React at 40°C for 24 h, add ethyl acetate for extraction, separate, and concentrate the organic phase under reduced pressure. Wash with petroleum ether to obtain the intermediate 3,5-di(propyleneoxy)benzaldehyde.

[0035] 100 mL of ethanol, 20 mmol of the 3,5-bis(propyleneoxy)benzaldehyde intermediate, and 18 mmol of cysteine were added to a flask and reacted at 70°C for 24 h. After cooling, 40 mmol of sodium borohydride was added for reduction. After the reaction, the ethanol was removed by concentration, and 5% acetic acid solution and dichloromethane were added for extraction. After separation, the organic phase was concentrated under reduced pressure and washed with petroleum ether to obtain the dipropylene glycol imine thioglycolic acid intermediate.

[0036] 20 g of the m-dipropyleneoxyphenyliminethioglycolic acid intermediate and 250 mL of N,N-dimethylacetamide were added to a flask, nitrogen was introduced, and 0.4 g of triethylamine as a catalyst was added dropwise. The reaction was stirred at room temperature for 36 h. After the reaction, methanol was added to the solution to precipitate, which was filtered, washed with ethanol, and dried to obtain a carboxyl hyperbranched polymer.

[0037] To a reaction flask, 50 mL of water, 0.5 g of sodium dodecylsulfonate, 6 g of methyl methacrylate, 18 g of butyl acrylate, 1.4 g of glycidyl methacrylate, and 0.7 g of hydroxyethyl acrylate were added. After stirring the solvent, an aqueous solution of ammonium persulfate was added dropwise. The mixture was reacted at 65°C for 3 h and cooled to obtain an emulsion of glycidyl methacrylate-based acrylic resin.

[0038] A carboxyl hyperbranched polymer is added to an emulsion of a glycidyl acrylate-based acrylic resin, wherein the carboxyl hyperbranched polymer accounts for 8% of the mass of the glycidyl acrylate-based acrylic resin, the defoamer RP-6301 accounts for 0.1%, the leveling agent PLP-650 accounts for 0.3%, and the film-forming aid dipropylene glycol methyl ether accounts for 2%. The mixture is dispersed at high speed to obtain a carboxyl hyperbranched polymer-modified coating.

[0039] Example 5 Add 200 mL of toluene, 10 mmol of 3,5-dihydroxybenzaldehyde, and 28 mmol of 2-bromopropylene to a flask, stir to dissolve, and add 0.12 mmol of catalyst tetrabutylammonium bromide and 150 mL of an aqueous solution containing 35 mmol of sodium hydroxide. React at 40°C for 24 h, add ethyl acetate for extraction, separate, and concentrate the organic phase under reduced pressure. Wash with petroleum ether to obtain the intermediate 3,5-di(propyleneoxy)benzaldehyde.

[0040] 150 mL of ethanol, 20 mmol of the 3,5-di(propyleneoxy)benzaldehyde intermediate, and 28 mmol of cysteine were added to a flask and reacted at 65°C for 18 h. After cooling, 40 mmol of sodium borohydride was added for reduction. After the reaction, the ethanol was concentrated to remove the ethanol. 6% acetic acid solution and dichloromethane were added for extraction. After separation, the organic phase was concentrated under reduced pressure and washed with petroleum ether to obtain the dipropylene glycol imine thioglycolic acid intermediate.

[0041] 20 g of the m-dipropyleneoxyphenyliminethioglycolic acid intermediate and 250 mL of N,N-dimethylacetamide were added to a flask, nitrogen was introduced, and 0.3 g of triethylamine as a catalyst was added dropwise. The mixture was stirred at room temperature for 12 h. After the reaction, methanol was added to the solution to precipitate the precipitate, which was filtered, washed with ethanol, and dried to obtain a carboxyl hyperbranched polymer.

[0042] To a reaction flask, add 50 mL of water, 0.4 g of sodium dodecylsulfonate, 5.2 g of methyl methacrylate, 18 g of butyl acrylate, 1.5 g of glycidyl methacrylate, and 1.2 g of hydroxyethyl acrylate. After stirring the solvent, add dropwise an aqueous solution of ammonium persulfate. React at 60 °C for 3 h and cool to obtain an emulsion of glycidyl methacrylate-based acrylic resin.

[0043] A carboxyl hyperbranched polymer is added to an emulsion of a glycidyl acrylate-based acrylic resin, wherein the carboxyl hyperbranched polymer accounts for 10% of the mass of the glycidyl acrylate-based acrylic resin, the defoamer RP-6301 accounts for 0.2%, the leveling agent PLP-650 accounts for 0.3%, and the film-forming aid dipropylene glycol methyl ether accounts for 3%. The mixture is dispersed at high speed to obtain a carboxyl hyperbranched polymer-modified coating.

[0044] Comparative Example 1 To the reaction flask, 50 mL of water, 0.36 g of sodium dodecylsulfonate, 4.5 g of methyl methacrylate, 15 g of butyl acrylate, 1.2 g of glycidyl methacrylate, and 1.2 g of hydroxyethyl acrylate were added. After stirring the solvent, an aqueous solution of ammonium persulfate was added dropwise. The mixture was reacted at 60 °C for 3 h. After cooling, 0.2% of defoamer RP-6301, 0.2% of leveling agent PLP-650, and 3% of film-forming aid dipropylene glycol methyl ether were added and dispersed at high speed to obtain an acrylic resin coating.

[0045] The test results of carboxyl hyperbranched polymer modified coatings are as follows:

[0046] When carboxyl hyperbranched polymers were added to the acrylic resins of Examples 1-5, the adhesion reached level 0 and the pencil hardness reached a maximum of 4H. This is because during the curing process, the carboxyl groups of the hyperbranched polymers reacted with the epoxy groups of the acrylic resin to form a stable cross-linked curing system, thereby enhancing the adhesion and hardness of the paint film.

[0047] The water resistance test results of carboxyl hyperbranched polymer modified coatings are as follows:

[0048] The carboxyl groups of the hyperbranched polymer can react with the epoxy groups of the acrylic resin to form a stable cross-linking curing system. The increased cross-linking degree of the acrylic resin molecular chain hinders the entry of corrosive media such as water molecules and salt into the paint film, thereby improving the water resistance and salt water resistance of the paint film.

[0049] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A preparation process for a carboxyl hyperbranched polymer modified coating, characterized in that: The preparation process comprises the following steps: Step S1, adding a m-dipropyleneoxyphenyliminethioglycolic acid intermediate and N,N-dimethylacetamide into a flask, introducing nitrogen, and dropwise adding a catalyst triethylamine. After the reaction, methanol is added to the solution to precipitate, which is filtered, washed, and dried to obtain a carboxyl hyperbranched polymer; Step S2: adding a carboxyl hyperbranched polymer, a defoamer, a leveling agent, and a film-forming aid to an emulsion of glycidyl acrylate-based acrylic resin, and dispersing the mixture at high speed to obtain a carboxyl hyperbranched polymer-modified coating.

2. The preparation process of the carboxyl hyperbranched polymer modified coating according to claim 1, wherein: The amount of triethylamine used in step S1 is 0.8-2% of the mass of the m-dipropyleneoxyphenyliminethioglycolic acid intermediate.

3. The preparation process of the carboxyl hyperbranched polymer modified coating according to claim 1, wherein: The reaction in step S1 is stirred at room temperature for 12-36 h.

4. The preparation process of the carboxyl hyperbranched polymer modified coating according to claim 1, wherein: In step S2, the carboxyl hyperbranched polymer is 1-10% of the mass of the glycidyl acrylate based acrylic resin.

5. The preparation process of the carboxyl hyperbranched polymer modified coating according to claim 1, wherein: The preparation process of the meta-dipropyleneoxyphenylimine thioglycolic acid intermediate comprises the following steps: Step S3: adding toluene, 3,5-dihydroxybenzaldehyde, and 2-bromopropylene to a flask, stirring to dissolve, and adding a catalyst of tetrabutylammonium bromide and an aqueous solution of sodium hydroxide, reacting at 40-60° C. for 12-24 hours, extracting, concentrating, and washing with ether to obtain a 3,5-di(propyleneoxy)benzaldehyde intermediate; Step S4: Add ethanol, 3,5-di(propyleneoxy)benzaldehyde intermediate and cysteine to a flask, react at 65-80° C. for 6-24 h, cool, add sodium borohydride for reduction, concentrate, extract, and wash to obtain a dipropyleneoxyphenylimine thioglycolic acid intermediate.

6. The preparation process of the carboxyl hyperbranched polymer modified coating according to claim 5, wherein: In step S3, the molar ratio of 3,5-dihydroxybenzaldehyde, 2-bromopropylene, tetrabutylammonium bromide, and sodium hydroxide is 1:(2.8-3.5):(0.01-0.015):(2.5-3.5).

7. The preparation process of the carboxyl hyperbranched polymer modified coating according to claim 5, wherein: In step S3, the molar ratio of the 3,5-bis(propyleneoxy)benzaldehyde intermediate to cysteine is 1:(0.8-1.4).

8. The preparation process of the carboxyl hyperbranched polymer modified coating according to claim 1, wherein: The preparation process of the emulsion of glycidyl acrylate-based acrylic resin in step S2 comprises the following steps: adding water, sodium lauryl sulfate, methyl methacrylate, butyl acrylate, glycidyl methacrylate, and hydroxyethyl acrylate to a reaction flask, stirring the solvent, and then dropwise adding an aqueous solution of ammonium persulfate, reacting at 60-70° C. for 2-3 hours, and cooling to obtain the emulsion of glycidyl acrylate-based acrylic resin.

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