CN103319665A - Single-component room-temperature multiple-self-crosslinking aqueous epoxy acrylate resin emulsion and preparation method thereof - Google Patents

Abstract

The invention discloses a single-component room temperature multiple self-crosslinking water-based epoxy acrylic resin emulsion and a preparation method thereof; in the method, an unsaturated fatty acid modified epoxy ester resin is firstly synthesized, and 40 to 50 parts of bisphenol Type A epoxy resin and 50-60 parts of unsaturated fatty acid are used as raw materials, under the action of a catalyst and under the protection of nitrogen, they are prepared by esterification reaction; Agent, monomer with hydrophilic group, monomer with self-crosslinking function and chain transfer agent, at 100-110°C, within 1-3 hours, drop into self-crosslinking epoxy ester resin at room temperature for free radical graft copolymerization reaction to obtain a one-component room temperature multiple self-crosslinking water-based epoxy acrylic resin; after adding an amine neutralizer for neutralization, then add deionized water to disperse to obtain a single-component double self-crosslinking water-based epoxy acrylic resin emulsion. The paint film of the emulsion dries quickly, has strong adhesion, high mechanical strength and excellent corrosion resistance.

Description

One-component room temperature multiple self-crosslinking waterborne epoxy acrylic resin emulsion and preparation method thereof

technical field

The invention belongs to the technical field of coatings, and in particular relates to a main body resin mainly used for anticorrosion coatings for iron and steel products, especially suitable for single-group protective and coating coatings for traffic vehicles, engineering machinery, and steel furniture manufacturing industries. One part room temperature self-crosslinking waterborne anti-corrosion coating.

technical background

As one of the three general-purpose thermosetting resins, epoxy resin has excellent adhesion, stability, wear resistance, corrosion resistance, insulation and mechanical strength, and is widely used in the coatings industry. However, traditional epoxy resins use a large amount of organic solvents in the application, which increases the cost on the one hand, and on the other hand, the shortcomings of organic solvents such as flammability, explosion, toxicity, and environmental pollution have brought a lot of inconvenience to storage and construction. . This shortcoming limits the large-scale use of epoxy resins in the coatings industry. With the improvement of environmental protection laws and regulations in various countries and the continuous enhancement of people's environmental protection awareness, water-based coatings that use water as a solvent and dispersant have developed rapidly as green and environmentally friendly coatings. The development of water-based coatings has become the future development trend of the coatings industry.

In order to improve the paint film properties of water-based paints so that they can achieve the excellent performance of solvent-based paint films, it has become a common requirement to form crosslinks after the paint film dries. Through crosslinking, the emulsion coating film forms a highly three-dimensional network structure, so that the water resistance, corrosion resistance and mechanical strength of the coating film are greatly improved compared with non-crosslinking emulsions. According to the crosslinking method, crosslinking can be divided into high temperature crosslinking, UV curing crosslinking and room temperature crosslinking. High temperature crosslinking requires heating and consumes a lot of energy, while the application range of UV curing crosslinking is limited, such as cannot be used in architectural coatings. The room temperature crosslinking can not only save energy, but also suitable for any painting and construction conditions. According to the packaging method, cross-linking can be divided into one-component cross-linking and two-component cross-linking. Two-component refers to the two components of the coating product and the curing agent. When packaging, the two components must be stored separately and prepared for immediate use. The use time after the two components are mixed is generally very short and must be used up at one time. Most of the existing water-based anti-corrosion coatings use two-components, which have high application costs and cumbersome construction operations, and single-component packaging can avoid these defects. Therefore, the development of one-component room temperature self-crosslinking water-based coatings has a broader market prospect and application value.

The polymer molecular chain of room temperature cross-linking water-based paint film-forming resin usually contains functional groups that can induce cross-linking through its own chemical reaction or external cross-linking agent. Self-crosslinking is achieved through self-condensation or autoxidation of functional monomers introduced into polymer molecular chains with self-condensation or autoxidation properties during film formation at room temperature. There are mainly four types of room temperature self-crosslinking systems: room temperature self-crosslinking based on N-methylolacrylamide and its derivatives, room temperature self-crosslinking by hydrolysis polycondensation of siloxane, room temperature self-crosslinking based on epoxy groups and room temperature autoxidative crosslinking of double bonds in unsaturated fatty acids. Most of the room temperature self-crosslinking coatings currently developed use a single crosslinking method. As people have higher and higher requirements for the coating film performance of coatings, the performance of single crosslinking water-based coatings often cannot meet the application requirements, while multiple crosslinking Lianneng can effectively increase the crosslinking density of the paint film, thereby improving the water resistance, abrasion resistance, corrosion resistance and mechanical strength of the paint film, which represents the development trend of self-crosslinking technology for water-based anti-corrosion coatings in the future.

Contents of the invention

The object of the present invention is to overcome the weak point of existing water-based epoxy resin corrosion coating, provide a kind of single-component room temperature multiple self-crosslinking water-based epoxy acrylic resin emulsion and preparation method thereof, its product advantage is to use water as solvent, Non-toxic and non-polluting, small emulsion particle size, good storage stability, good brushing performance, smooth paint film, high gloss, while maintaining strong adhesion, good water resistance, and corrosion resistance of solvent-based epoxy resin corrosion coatings and wear resistance and other excellent properties.

The water-based transformation of the single-component room temperature multiple self-crosslinking water-based epoxy acrylic resin emulsion described in the present invention adopts a free radical grafting modification method, and under the action of an initiator, the methylene on the epoxy resin molecular chain Initiate the formation of free radicals, graft copolymerize with acrylic monomers with carboxyl groups, introduce carboxyl groups into the epoxy resin molecular chain, and then disperse in water after neutralization to form a salt to obtain a self-emulsifying water-based epoxy emulsion. The emulsion particles prepared by the chemical modification method are small, usually at the nm level, and have good stability.

The multiple self-crosslinking of the single-component room temperature multiple self-crosslinking water-based epoxy acrylic resin emulsion mentioned in the present invention is realized by two ways: one is to generate ester under the action of catalyst through epoxy resin and unsaturated fatty acid The self-drying epoxy ester is produced by chemical reaction, and the self-oxidative cross-linking of the carbon-carbon double bond on the unsaturated fatty acid is used to realize the self-crosslinking of the coating at room temperature; Acrylic functional monomers (N‐methylolacrylamide and glycidyl methacrylate) with linking properties are copolymerized with other acrylic monomers through free radical graft polymerization and introduced into the molecular chain of epoxy resin , using the polycondensation of N-methylolacrylamide's own active groups or the cross-linking reaction with carboxyl-containing acrylic monomers in the system, and the hydroxyl groups generated after the epoxy groups of glycidyl methacrylate are opened. The room temperature multiple self-crosslinking of water-based epoxy acrylic resin emulsion can be realized through the two self-crosslinking methods of condensation dehydration reaction between them.

In order to achieve the above purpose, this technology adopts the following technical solutions:

Synthesis of Unsaturated Fatty Acid Modified Epoxy Ester Resin in the First Step

In terms of parts by mass, 40-50 parts of bisphenol A epoxy resin and 50-60 parts of unsaturated fatty acid are used as raw materials, under the action of 0.5-2 parts of catalyst and nitrogen protection, at 120-150 ° C. Esterification reaction, react until the mass fraction of unsaturated fatty acid drops to 60-70%, then raise the temperature to 190-210°C, react until the acid value of the system is lower than 5mgKOH/100g as the end point, and prepare self-crosslinking epoxy ester at room temperature resin;

In the above scheme, the epoxy resin is bisphenol A type epoxy resin E-20, E-12 or a mixture thereof; the unsaturated fatty acid is dehydrated ricinoleic acid, linoleic acid, oleic acid, or its mixture. The catalyst is one or more of tetrabutyl titanate, monobutyltin oxide, triphenylphosphine and tetrabutylammonium bromide;

Synthesis of the second-step one-component room temperature multiple self-crosslinking waterborne epoxy acrylic resin

Add the cosolvent into the self-crosslinking epoxy ester resin at room temperature, and control the solid content of the self-crosslinking epoxy ester resin at room temperature to 45-60% by mass percentage; 1-3 parts of initiator, 22-45 parts of monomers with hydrophilic groups, 8-15 parts of self-crosslinking functional monomers and 0.21-0.56 parts of chain transfer agent, at 100-110°C, within 1-3 hours Add it to self-crosslinking epoxy ester resin at room temperature to carry out free radical graft copolymerization reaction. After 0.5~1.5h of heat preservation, add 0.5~1 initiator and then heat preservation reaction for 2~4h, and finally heat up to 115~125℃ Insulation reaction for 1 to 3 hours to obtain single-component room temperature multiple self-crosslinking water-based epoxy acrylic resin;

In the above scheme, the monomer with hydrophilic group is acrylic acid, methacrylic acid, n-butyl acrylate, styrene or methyl methacrylate; the self-crosslinking functional monomer is glycidyl methacrylate and N-methylolacrylamide, the mass ratio of the two kinds is 1:10～1:20; the described initiator is benzoyl peroxide; the described chain transfer agent is n-butyl mercaptan, tert-butyl sulfide Alcohol, n-octyl mercaptan, n-dodecyl mercaptan, select one or more of them; the co-solvent is n-butanol, isopropanol, ethylene glycol butyl ether, propylene glycol methyl ether, select one of them or several.

The third step is the configuration of one-component room temperature multiple self-crosslinking waterborne epoxy acrylic resin emulsion

In terms of parts by mass, 45 to 60 parts of one-component room temperature multiple self-crosslinking water-based epoxy acrylic resins are neutralized by adding an amine neutralizer with a resin acid value equivalent of 70 to 100% at 40 to 60 ° C. Then add 40-55 parts of deionized water to disperse to obtain a one-component double self-crosslinking water-based epoxy acrylic resin emulsion.

In the above scheme, the neutralizing agent described in the third step configuration is triethylamine, N,N-dimethylethanolamine, triethanolamine, 2-amino-1-propanol, N-ethyl Lin, choose one or more of them, and the dosage is 70-100% of the acid value equivalent of the resin emulsion.

The two-step reaction of the present invention and the last step of emulsion configuration can be carried out in the same reactor, so the operation is convenient and energy is saved. The obtained water-based epoxy acrylic resin emulsion has low odor, and the appearance is light yellow and transparent, and the particle size distribution result shows that the particle size distribution of the emulsion is uniform, and the particle size is below 100nm.

The one-component room temperature multiple self-crosslinking water-based epoxy acrylic resin emulsion is sprayed, brushed or dipped on the surface of the steel material, and then dried naturally at room temperature for five days to form a film. After the film is formed, the paint film is smooth and transparent. It has excellent gloss, soaked in boiling water at 40°C for seven days without any whitening phenomenon, and the salt spray resistance can reach more than 200h.

Compared with the prior art, the beneficial effects of the present invention are as follows:

(1) The single-component room temperature multiple self-crosslinking water-based epoxy acrylic resin emulsion prepared by the present invention combines the excellent adhesion, wear resistance, corrosion resistance, insulation and mechanical strength of epoxy resin, and acrylic resin It has the advantages of excellent gloss and outdoor aging resistance. At the same time, through the self-emulsification method, the carboxyl group of (meth)acrylic acid and other hydrophilic groups are introduced into the epoxy resin to make it water-based. Not only is the product non-toxic and pollution-free, It meets the requirements of environmental protection, and the prepared emulsion has small particles and good storage stability.

(2) The emulsion product is packaged in one component, and can be self-crosslinked and cured to form a film at room temperature. It does not need to add a curing agent during use, and does not require heating or radiation during the film formation process. Therefore, it not only reduces energy consumption and saves costs, but also It avoids the defect of complex construction and operation of two-component packaging, and is more convenient to use.

(3) In terms of coating film performance, this emulsion is different from the single self-crosslinking of the previous one-component coatings, but adopts multiple self-crosslinking structures to further increase the crosslinking density of the coating film, and the drying speed of the paint film becomes faster , so that the adhesion, water resistance, corrosion resistance and wear resistance of the coating film have been improved to a greater extent.

Detailed ways

In order to better understand the present invention, the present invention will be further described below in conjunction with the examples, but the protection scope of the present invention is not limited to the range expressed in the examples.

Example 1

The preparation method of one-component room temperature multiple self-crosslinking waterborne epoxy acrylic resin emulsion comprises the following steps:

a. After adding 30g E-12 type epoxy resin and 20g E-20 type epoxy resin into the reaction kettle protected by nitrogen gas, heat up to 100°C and keep it warm for 0.5h to make the E-12 type epoxy resin in solid state completely After melting, start stirring, then add a mixture of 38g of linoleic acid and 15g of oleic acid, and add 0.5g of catalyst monobutyltin oxide, heat up to 140°C and keep it warm for 3 hours, at this time, the mass concentration of unsaturated fatty acids in the system decreases The acid value of the system is 2.8mgKOH/g, which is the end point of the reaction, and then the room temperature self-crosslinking epoxy ester resin modified by unsaturated fatty acid is obtained.

b. Add 60g of n-butanol to the above-mentioned reaction kettle equipped with 40g of self-crosslinking epoxy ester resin synthesized at room temperature and stir to raise the temperature to 105°C. Transfer agent n-dodecanethiol, add dropwise 4g methacrylic acid, 30g styrene, 6.7g n-butyl acrylate, 6.3g methyl methacrylate, 1g glycidyl methacrylate and 12g N-methylolacrylamide ( Dissolve with 40g ethylene glycol butyl ether), after dropwise addition within 2h, heat up to 110°C for 1h, then add the remaining 0.42g initiator (dissolve with 20g propylene glycol methyl ether), continue to keep warm for 2h, and finally heat up to One-component room temperature multiple self-crosslinking epoxy acrylic resin with a solid content of 45% can be obtained by heat-retaining at 120°C for 1 hour.

c. Add 1.5g of neutralizing agent triethylamine and 4g of deionized water to 50g of single-component room temperature multiple self-crosslinking epoxy acrylic resin with a solid content of 45%, and stir and disperse at 500r/min for 30min to obtain a solid One-component room temperature multiple self-crosslinking epoxy acrylic resin emulsion with a content of 26%.

The emulsion is light yellow transparent liquid with little odor, the particle size of the emulsion is 92nm, the viscosity is 300mPa.s, and the acid value is 22.5mgKOH/g. After being sprayed on the steel surface, it will be dried for five days at room temperature to form a film. The coating film is smooth and smooth, with excellent gloss. It can be soaked in boiling water at 40°C for seven days without any whitening phenomenon, and the salt spray resistance can reach more than 200h.

Example 2

The preparation method of one-component room temperature multiple self-crosslinking waterborne epoxy acrylic resin emulsion comprises the following steps:

a. Add 40g of E-12 epoxy resin to the reaction kettle protected by nitrogen gas, raise the temperature to 110°C, keep it warm for 0.5h to completely melt the E-12 epoxy resin in solid state, start stirring, and then add A mixture of 30g of dehydrated ricinoleic acid and 20g of oleic acid, and adding 2g of catalyst triphenylphosphine, heating up to 150°C and then keeping it warm for 3h. At this time, the mass concentration of unsaturated fatty acids in the system dropped to 70%, and then the temperature was raised to 200°C After holding the reaction at ℃ for 5 hours, the acid value of the system is 3.1 mgKOH/g, which is the end point of the reaction, and a room temperature self-crosslinking epoxy ester resin modified by unsaturated fatty acid is obtained.

b. In the reaction kettle equipped with 55g room temperature self-crosslinking epoxy ester resin synthesized above, add 50g n-butanol to dilute and stir to raise the temperature to 110°C. Under the action of transfer agent n-octyl mercaptan, add dropwise 4g methacrylic acid, 13g styrene, 4.7g n-butyl acrylate, 2.3g methyl methacrylate, 1g glycidyl methacrylate and 20g N-methylol propylene Amide (dissolved with 30g ethylene glycol butyl ether), dropwise added within 2h, then raised the temperature to 115°C for 1h, then added the remaining 0.55g initiator (dissolved with 40g propylene glycol methyl ether), continued to keep warm for 2h, and finally Raise the temperature to 120°C and keep it warm for 1 hour to obtain a one-component room temperature multiple self-crosslinking epoxy acrylic resin with a solid content of 50%.

c. Add 1.7g of neutralizing agent N′N‐dimethylethanolamine and 4g of deionized water to 55g of one-component room temperature multiple self-crosslinking epoxy acrylic resin with a solid content of 50%, and stir and disperse at 500r/min for 30min , a single-component room temperature multiple self-crosslinking epoxy acrylic resin emulsion with a solid content of 28% can be obtained.

The emulsion is a light yellow transparent liquid with little odor, the particle size of the emulsion is 89nm, the viscosity is 275mPa.s, and the acid value is 21mgKOH/g. After being sprayed on the steel surface, it will be dried for five days at room temperature to form a film. The coating film is smooth and smooth, with excellent gloss. It can be soaked in boiling water at 40°C for seven days without any whitening phenomenon, and the salt spray resistance can reach more than 200h.

Example 3:

The preparation method of one-component room temperature multiple self-crosslinking waterborne epoxy acrylic resin emulsion comprises the following steps:

a. After adding 30g E-12 type epoxy resin and 10gE-20 type epoxy resin into the reaction kettle with nitrogen protection, raise the temperature to 100°C and keep it warm for 0.5h to make the E-12 type epoxy resin in solid state completely After melting, start stirring, then add 37g of linolenic acid, and add 1g of catalyst tetrabutylammonium bromide, heat up to 160°C and keep it warm for 2 hours, at this time, the mass concentration of unsaturated fatty acids in the system drops to 65%, and then After raising the temperature to 210°C and keeping it warm for 6 hours, the acid value of the system was 2.8 mgKOH/g, which was the end point of the reaction, and a room temperature self-crosslinking epoxy ester resin modified by unsaturated fatty acid was obtained.

b. In the reaction kettle equipped with the synthesized 70g room temperature self-crosslinking epoxy ester resin, add 40g n-butanol to dilute the epoxy ester and stir to raise the temperature to 105°C. Under the action of 0.24g chain transfer agent n-butyl mercaptan, drop 4g methacrylic acid, 6.7g styrene, 2.3g methyl methacrylate, 1.5g glycidyl methacrylate and 15.5g N-methylolacrylamide (dissolved with 30g ethylene glycol butyl ether), after adding dropwise within 2h, heat it up to 115°C for 1h, then add the remaining 0.86g initiator (dissolved with 10g propylene glycol methyl ether), continue to keep warm for 2h, and finally raise the temperature again Heat the reaction at 125°C for 1 hour to obtain a one-component room temperature multiple self-crosslinking epoxy acrylic resin with a solid content of 55%.

c. Add 1.9g of neutralizing agent 2-amino-1-propanol and 4g of deionized water to 60g of one-component room temperature multiple self-crosslinking epoxy acrylic resin with a solid content of 55%, and stir and disperse at 500r/min for 30min. A one-component room temperature multiple self-crosslinking epoxy acrylic resin emulsion with a solid content of 30% can be obtained.

The emulsion is light yellow transparent liquid with little odor, the particle size of the emulsion is 80nm, the viscosity is 290mPa.s, and the acid value is 22.5mgKOH/g. After being sprayed on the steel surface, it will be dried for five days at room temperature to form a film. The coating film is smooth and smooth, with excellent gloss. It can be soaked in boiling water at 40°C for seven days without any whitening phenomenon, and the salt spray resistance can reach more than 200h.

For the above-mentioned embodiments, the products obtained in each embodiment were tested according to the national standards of the paint industry, and the test results are shown in Table 1. The detection result of table 1 and the basic test data of product, compared with the existing water-based paint on the market, have illustrated that the product of the present invention is non-toxic and pollution-free, has small emulsion particle size, good storage stability, good brushing performance, and paint The film is smooth and smooth, with high gloss, while maintaining the excellent properties of solvent-based epoxy resin corrosion coatings such as strong adhesion, good water resistance, corrosion resistance and wear resistance.

The one-component room temperature multiple self-crosslinking water-based epoxy acrylic resin emulsion and its coating film properties obtained by three kinds of embodiments in Table 1

Claims (7)

1. the preparation method of single-component room temperature multiple self-crosslinking waterborne epoxy acrylic resin emulsion is characterized in that comprising the following steps: Synthesis of Unsaturated Fatty Acid Modified Epoxy Ester Resin in the First Step In terms of parts by mass, 40-50 parts of bisphenol A epoxy resin and 50-60 parts of unsaturated fatty acid are used as raw materials, under the action of 0.5-2 parts of catalyst and nitrogen protection, at 120-150 ° C. Esterification reaction, react until the mass fraction of unsaturated fatty acid drops to 60-70%, then raise the temperature to 190-210°C, react until the acid value of the system is lower than 5mgKOH/100g as the end point, and prepare self-crosslinking epoxy ester at room temperature Resin; the catalyst is one or more of tetrabutyl titanate, monobutyltin oxide, triphenylphosphine and tetrabutylammonium bromide; Synthesis of the second-step one-component room temperature multiple self-crosslinking waterborne epoxy acrylic resin Add the cosolvent into the self-crosslinking epoxy ester resin at room temperature, and control the solid content of the self-crosslinking epoxy ester resin at room temperature to 45-60% by mass percentage; 1-3 parts of initiator, 22-45 parts of monomers with hydrophilic groups, 8-15 parts of self-crosslinking functional monomers and 0.21-0.56 parts of chain transfer agent, at 100-110°C, within 1-3 hours Add it to self-crosslinking epoxy ester resin at room temperature to carry out free radical grafting copolymerization reaction. After 0.5-1.5 hours of heat preservation, add 0.5-1 part of initiator and then heat-reaction for 2-4 hours, and finally raise the temperature to 115-125 ℃ After heat preservation for 1-3 hours, a single-component room temperature multiple self-crosslinking water-based epoxy acrylic resin is obtained; The monomer having a hydrophilic group is acrylic acid, methacrylic acid, n-butyl acrylate, styrene or methyl methacrylate; The self-crosslinking functional monomer is glycidyl methacrylate and N-methylol acrylamide with a mass ratio of 1:10 to 1:20; Described initiator is benzoyl peroxide; The third step is the configuration of one-component room temperature multiple self-crosslinking waterborne epoxy acrylic resin emulsion In terms of parts by mass, 45 to 60 parts of one-component room temperature multiple self-crosslinking water-based epoxy acrylic resins are neutralized by adding an amine neutralizer with a resin acid value equivalent of 70 to 100% at 40 to 60 ° C. Then add 40-55 parts of deionized water to disperse to obtain a one-component double self-crosslinking water-based epoxy acrylic resin emulsion. 2. according to the preparation method of single-component room temperature multiple self-crosslinking waterborne epoxy acrylic resin emulsion described in right 1, it is characterized in that: described bisphenol A type epoxy resin is bisphenol A type epoxy resin E- 20. E‐12 or mixtures thereof. 3. the preparation method of single-component room temperature multiple self-crosslinking water-based epoxy acrylic resin emulsion according to right 1, is characterized in that: described unsaturated fatty acid is dehydrated ricinoleic acid, linoleic acid and oleic acid one or more. 4. the preparation method of single-component room temperature multiple self-crosslinking waterborne epoxy acrylic resin emulsion according to right 1, is characterized in that: described chain transfer agent is n-butyl mercaptan, tert-butyl mercaptan, n-octyl thiol alcohol, n-dodecanethiol or isooctyl mercaptopropionate. 5. the preparation method of single-component room temperature multiple self-crosslinking waterborne epoxy acrylic resin emulsion according to right 1, is characterized in that: described cosolvent includes but not limited to n-butanol, isopropanol, ethylene glycol Butyl ether or propylene glycol methyl ether. 6. The preparation method of single-component room temperature multiple self-crosslinking waterborne epoxy acrylic resin emulsion according to right 1, it is characterized in that: described amine neutralizer includes but not limited to triethylamine, N,N‐ Dimethylethanolamine, triethanolamine or 2-amino-1-propanol or N-ethylmorpholine. 7. A single-component room temperature multiple self-crosslinking water-based epoxy acrylic resin emulsion is characterized in that it is made by any one of the preparation methods described in claims 1-6.