WO2022088837A1 - Halogen-free flame-retardant cationic electrodeposition coating - Google Patents

Abstract

A halogen-free flame-retardant cationic electrodeposition coating, which comprises an amino modified epoxy resin and a blocked isocyanate curing agent and is further mixed with 15% - 35% of bisphenol A polyoxyethylene ether phosphate. A method for preparing the halogen-free flame-retardant cationic electrodeposition coating.

Description

A halogen-free flame retardant cationic electrodeposition coating technical field

The invention relates to the technical field of flame retardant coatings, in particular to a halogen-free flame retardant cationic electrodeposition coating.

Background technique

Due to its excellent coating workability, cationic electrodeposition coatings can uniformly coat all parts of metal workpieces with complex shapes and structures, and the formed coating film has good physical and chemical properties, so it is widely used in automobiles, tricycles, machinery. , hardware and other industries are widely used.

In recent years, the new energy vehicle industry has developed rapidly. As a key component of new energy vehicles, batteries must not only provide the car with good battery life, but also ensure the safety of use. At present, battery manufacturers of new energy vehicles are gradually requiring the battery shell to have a flame retardant effect, which can play a flame retardant role in the event of abnormal combustion of the battery and protect the external components of the battery from being ignited. At present, there is no electrodeposition coating application with flame retardant function on the market.

SUMMARY OF THE INVENTION

The purpose of the present invention is to solve the deficiencies of the prior art, and to provide a cationic electrodeposition coating with good electrodeposition coating adaptability and excellent corrosion resistance on various metal substrates

In order to achieve the above purpose, a halogen-free flame retardant cationic electrodeposition coating is designed, which includes amino-modified epoxy resin and blocked isocyanate curing agent, and is also mixed with 15% to 35% of bisphenol A polyoxyethylene ether phosphate.

The present invention also has the following preferred technical solutions:

Further, the bisphenol A polyoxyethylene ether phosphate comprises 306.1 parts of phosphorus oxychloride, 900 parts of acetonitrile, 136.5 parts of pentaerythritol, 930 parts of bisphenol A polyoxyethylene ether and 1.8 parts of catalyst.

Further, the amino-modified epoxy resin includes 2180 parts of a basic epoxy resin with an epoxy equivalent of 180-190, 860 parts of bisphenol A, 165.2 parts of cardanol, and 100 parts of methyl isobutyl ketone , 3 parts of dimethylbenzylamine, 400 parts of methyl isobutyl ketone, 189.4 parts of N-methylethanolamine, 231.2 parts of ketimine, and 250 parts of ethylene glycol monobutyl ether.

Further, the blocked isocyanate curing agent includes a polyisocyanate and an active hydrogen-containing compound in a molar ratio of 1:1 to 1:1.2.

Another aspect of the present invention also includes a method for preparing a halogen-free flame-retardant cationic electrodeposition coating, the method comprising the following steps:

S1. Add amino-modified epoxy resin, bisphenol A polyoxyethylene ether, and closed isocyanate curing agent to the reactor and stir;

S2. Add acetic acid to the reactor, and disperse at a temperature of 40°C to 50°C for 1 hour;

S3. Deionized water is added to the reactor, and an emulsion is obtained after emulsification;

S4. Mix the emulsion with color paste and deionized water to obtain the halogen-free flame-retardant cationic electrodeposition coating.

Further, before the step S1, the following steps are also included:

S0.1 Preparation of amino-modified epoxy resin: the basic epoxy resin, bisphenol A, cardanol, and methyl isobutyl ketone are stirred and mixed, then heated to 100 °C, added with dimethylbenzylamine catalyst, and then heated to 180 °C -190°C for 20 minutes, then the temperature was lowered to 140-150°C for 2 hours, and when the temperature was lowered to 100°C, methyl isobutyl ketone was added and mixed, and the temperature was kept between 90-95°C, and N-methylethanolamine was added. and ketimine, heat up to 110-120°C for 3 hours, add ethylene glycol butyl ether, cool down to 90°C, and disperse for 20min to obtain the amino-modified epoxy resin;

S0.2 Preparation of bisphenol A polyoxyethylene ether phosphate: at a temperature of 45-50 °C, add pentaerythritol dropwise to the mixture of phosphorus oxychloride and acetonitrile, raise the temperature to 55-60 °C for 30 minutes, add bisphenol After adding the phenol A polyoxyethylene ether and the catalyst, the mixture is raised to the reflux temperature for 3 hours, and the reaction is carried out for 3 hours. After filtration and distillation, the bisphenol A polyoxyethylene ether phosphate is obtained.

S0.3 Prepare blocked isocyanate curing agent.

Beneficial Effects of Invention

The advantages of the halogen-free flame-retardant cationic electrodeposition coating provided by the invention are: bisphenol A polyoxyethylene ether phosphate has good compatibility with epoxy resin, is not easy to separate out, is not easy to be hydrolyzed, and can be used for epoxy resin. The resin is toughened to provide good flexibility of the paint film, and at the same time, it does not affect the chemical corrosion resistance of the paint film, which solves the problem of poor compatibility between ordinary phosphate ester flame retardants and epoxy resins, easy precipitation, and unsatisfactory stability of electrophoretic coatings. Construction application environment and other issues. Phosphorus contained in bisphenol A polyoxyethylene ether phosphate and nitrogen contained in amino-modified epoxy resin and blocked isocyanate curing agent cooperate with each other, resulting in a significant synergistic effect, forming a phosphorus-nitrogen flame retardant system, making electrophoresis possible. The paint film has good flame retardant properties.

Description of drawings

FIG. 1 is a schematic diagram of the molecular structure of the bisphenol A polyoxyethylene ether phosphate.

Detailed ways

The technical solutions adopted in the present invention will be further described below through examples.

After in-depth research in the present invention, it is found that a cationic electrodeposition coating composition can achieve good electrodeposition coating adaptability and excellent corrosion resistance on various metal substrates. Phenol A polyoxyethylene ether phosphate mixed with epoxy resin and curing agent.

The epoxy resin is an amino-modified epoxy resin. Through the basic epoxy resin (epoxy equivalent: 180-190) and a chain extender, under the action of a catalyst, a ring-opening chain extension reaction is carried out at a temperature of 130°C-190°C. After the theoretical epoxy equivalent is reached, the temperature is lowered to 90-100° C., organic amine compound is added, and the amination and chain extension reactions are carried out at 110-120° C. to obtain the aminated amino-modified epoxy resin.

Epoxy resins are usually aliphatic, alicyclic and aromatic compounds containing 1, 2 to epoxy groups per molecular structure, and the epoxy equivalent of the epoxy resin is between 100-1500g/mol , particularly suitable epoxy resins include, but are not limited to, bisphenol A type epoxy resin, bisphenol S type epoxy resin, bisphenol F type epoxy resin, polyethylene glycol diglycidyl ether and polypropylene glycol diglycidyl Any one or a mixture of any two or more ethers.

The chain extender is polycarboxylic acid, polyether polyol, polyester polyol, polyhydric mercaptool, polyhydric phenol and amine with two or more active hydrogens, and the molecular weight of the chain extender is between 50 and 4000. Among them, particularly suitable chain extenders include, but are not limited to, dicarboxylic acids, polyether polyols, polyester polyols, bisphenol A type polyether polyols, dihydric mercapto alcohols, monophenols, bisphenol compounds Any one or a mixture of any two or more.

Organic amine compounds are usually: butylamine, octylamine, diethylamine, methylbutylamine, monoethanolamine, diethanolamine, N-methylethanolamine, 1,3-dimethylpropylamine, N,N-dimethylamine Ethanolamine salts, etc.; also include ketimine organic amines. Among them, preferred are: diethanolamine, N-methylethanolamine, methyl isobutyl ketimine, ketimine-modified polyamide, and the like.

The curing agent is a blocked isocyanate curing agent, which is usually prepared by the reaction of polyisocyanates and compounds containing active hydrogen. Among them, the compound containing active hydrogen is slowly added dropwise to the polyisocyanate compound for reaction in about 1 to 3 hours. After the dropwise addition is completed, the reaction is kept at 70-110 °C for 1 to 5 hours. The molar ratio of isocyanate and compound containing active hydrogen in the polyisocyanate curing agent is: 1:1 to 1:1.2. The polyisocyanates used in the preparation process include but are not limited to any one of aliphatic diisocyanates, alicyclic diisocyanates, aromatic diisocyanates, triisocyanates, and tetraisocyanates or a mixture of any two or more, including toluene diisocyanate , diphenylmethane diisocyanate, polymethylene polyphenylene diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, isophorone diisocyanate, trimethylhexamethylene diisocyanate, etc.; Active hydrogen-containing compounds are any one or a mixture of any two or more of alcohols, alcohol ethers, phenols, amines, carboxylic acids, amides, and oximes containing 1-20 carbon atoms, including methanol, ethanol, and isopropanol. , phenol, ethylene glycol monobutyl ether, ethylene glycol ethyl ether, ethylene glycol hexyl ether, diethylene glycol monobutyl ether, diethylene glycol ethyl ether, aniline, dimethylethanolamine, methyl ethyl ketoxime, caprolactam, 1,3 - Dimethylpyrazole, etc.

Described bisphenol A polyoxyethylene ether phosphate is under nitrogen protection, under the condition of temperature 45-50 ℃, drop pentaerythritol into phosphorus oxychloride and acetonitrile mixture, after dropping is completed, the temperature rises to 55-60 ℃ for insulation 30 minutes, then add bisphenol A polyoxyethylene ether and catalyst to the reaction, after adding, the temperature rises to reflux temperature and keep reacting for 3 hours, filter and distill to obtain bisphenol A polyoxyethylene ether phosphate. Its structure is shown in Figure 1 of the description. Among them: X+Y=2～12.

For a further understanding of the present invention, the following examples illustrate more specific details, but the embodiments of the present invention are not limited thereto.

Example 1

Preparation of amino-modified epoxy resin

component	Dosage (g)
Basic epoxy resin (EEW=180-190)	2180
Bisphenol A	860
Cardanol	156.2
methyl isobutyl ketone	100
dimethylbenzylamine	3
methyl isobutyl ketone	400
N-Methylethanolamine	189.4
Ketimine	231.2
Ethylene glycol monobutyl ether	250
total	4369.8

The ketimine is prepared by the reaction of diethylenetriamine and methyl isobutyl ketone, the solid content of the final product is 70%, and the amine value is 450-480 mgKOH/g.

In the reaction flask equipped with a thermometer, agitator and a reflux condenser, add epoxy resin, bisphenol A, cardanol, and methyl isobutyl ketone according to the formula in turn. After adding dimethylbenzylamine catalyst at 100°C, the temperature was raised to 180-190°C for 20min, and then the temperature was lowered to 140-150°C for 2h. When the epoxy equivalent of the system reached 1000-1100, the temperature was lowered; When it drops to 100℃, add methyl isobutyl ketone, stir evenly and adjust the temperature of the system between 90-95℃, add N-methylethanolamine and ketimine at one time, and heat up to 110-120℃ for 3 hours; After the end, ethylene glycol butyl ether was added and the temperature was lowered to 90° C. and dispersed for 20 min. An amino-modified epoxy resin with a final resin solid content of 86% was obtained.

Preparation of Bisphenol A Polyoxyethylene Ether Phosphate

component	Dosage (g)
Phosphorus oxychloride	306.1
Acetonitrile	900
Pentaerythritol	136.5
Bisphenol A polyoxyethylene ether	930
catalyst	1.8
total	2274.4

Bisphenol A polyoxyethylene ether: hydroxyl value=220-230 mgKOH/g, Mn=480-550.

In the reaction flask equipped with thermometer, stirrer and reflux condenser, under nitrogen protection, under the condition of temperature 45-50 ℃, add pentaerythritol dropwise to the mixture of phosphorus oxychloride and acetonitrile, and the temperature rises to 55- 60 DEG C of heat preservation for 30 minutes, then add bisphenol A polyoxyethylene ether and catalyst to the reaction, after adding, the temperature rises to reflux temperature and heat preservation reaction for 3 hours, after filtration and distillation, bisphenol A polyoxyethylene ether phosphate is obtained.

Preparation of Blocked Isocyanate Curing Agent

In a reaction flask equipped with a thermometer, a stirrer and a reflux condenser, the formula amounts of polymethylene polyphenyl diisocyanate and methyl isobutyl ketone were sequentially added. Start stirring in a nitrogen atmosphere to raise the temperature of the reaction system to 45-50°C, mix ethylene glycol butyl ether and ethylene glycol ethyl ether evenly, and slowly add polymethylene polyphenylene diisocyanate, methyl isobutyl In the reaction system of ketone, the temperature of the reaction system is between 50-55°C during the dropwise addition, and the dropping is completed for about 4-5h. When the cyanate group content is less than 0.5%, it is qualified, and a blocked isocyanate curing agent with a solid content of 89% is obtained.

Example 2

Preparation of Cationic Electrodeposition Coating Emulsion

Emulsion A

Add amino-modified epoxy resin closed type, bisphenol A polyoxyethylene ether, isocyanate curing agent to the reactor equipped with thermometer and stirrer, add acetic acid with stirring, disperse at 40-50 °C for 1 hour to neutralize and make the resin After ionization, the required deionized water was added in sequence, and an emulsion with a solid content of 33% was obtained after emulsification for 30 minutes.

lotion B

Add amino-modified epoxy resin, bisphenol A polyoxyethylene ether phosphate, blocked isocyanate curing agent to the reactor equipped with thermometer and stirrer, add acetic acid with stirring, disperse at 40-50°C for 1 hour and neutralize it. The resin was ionized, and finally required deionized water was added in sequence, and an emulsion with a solid content of 33% was obtained after emulsification for 30 minutes.

Example 3

Preparation of color paste

Add 830 g of pigment dispersion resin with a solid content of 62%, 1450 g of titanium oxide, 700 g of kaolin, 30 g of carbon black, 100 g of dioctyl tin oxide, 100 g of bismuth hydroxide and 200 g of deionized water. The color paste with a content of 56%.

Preparation of Cationic Electrodeposition Coatings

1000 g of the cationic electrodeposition paint emulsion in Example 2, 500 g of color paste in the above-mentioned Example 3, and 2500 g of deionized water were mixed to prepare a cationic electrodeposition paint with a solid content of 15%.

The technical effects produced by the present invention will be further described below through experiments.

Manufacture of test boards

Cold-rolled sheet (0.6mm*150mm*70mm), galvanized steel sheet (0.6mm*150mm*70mm), die-casting aluminum sheet (0.6mm*150mm*70mm), magnesium-aluminum alloy sheet (0.6mm*150mm*70mm), through After degreasing pretreatment, as the parts to be painted, the cationic electrodeposition paints obtained from emulsion A and emulsion B in Example 2 (hereinafter referred to as paint A and paint B, respectively) were used to paint them, and all plates were not surfaced. Chemical treatment is more able to detect the suitability of the sheet.

Testing the electrodeposition suitability of coatings to metal substrates

After coating the test panels with paints A and B respectively, the paint films were baked at 165°C for 20min, and the number of pores of the dried test piece was calculated.

Testing paint for corrosion resistance

After coating A and B respectively on the test panels of the same material, the paint films were all baked at 165°C for 20 minutes, and the film thickness was controlled at 20-24 microns. According to the national standard NSS test, the 1000h salt spray test was used to evaluate the blistering of the cut part. number and expansion width.

Testing the flame retardant properties of coatings

After the test panels of the same material were coated with Coatings A and B, the paint films were baked at 165°C for 20 minutes, and the film thickness was controlled at 20-24 microns. With or without an open flame.

The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. The idea plus equivalent replacements or changes should all be included within the protection scope of the present invention.

Claims (6)

1. A halogen-free flame-retardant cationic electrodeposition coating, comprising an amino-modified epoxy resin and a blocked isocyanate curing agent, characterized in that the halogen-free flame-retardant cationic electrodeposition coating is further mixed with 15% to 35% of bisulfite Phenol A polyoxyethylene ether phosphate.
2. The halogen-free flame-retardant cationic electrodeposition coating according to claim 1, wherein the bisphenol A polyoxyethylene ether phosphate comprises 306.1 parts of phosphorus oxychloride, 900 parts of acetonitrile, 136.5 parts of Pentaerythritol, 930 parts of bisphenol A polyoxyethylene ether and 1.8 parts of catalyst.
3. The halogen-free flame-retardant cationic electrodeposition coating according to claim 1, wherein the amino-modified epoxy resin comprises 2180 parts of basic epoxy resin with an epoxy equivalent of 180-190, 860 parts of Bisphenol A, 165.2 parts of cardanol, 100 parts of methyl isobutyl ketone, 3 parts of dimethylbenzylamine, 400 parts of methyl isobutyl ketone, 189.4 parts of N-methylethanolamine, 231.2 parts of ketimine , 250 parts of ethylene glycol monobutyl ether.
4. The halogen-free flame-retardant cationic electrodeposition coating according to claim 1, wherein the blocked isocyanate curing agent comprises a polyisocyanate and an active hydrogen-containing compound in a molar ratio of 1:1 to 1:1.2.
5. A preparation method of halogen-free flame-retardant cationic electrodeposition coating, characterized in that, comprising the following steps:

   S1. Add amino-modified epoxy resin, bisphenol A polyoxyethylene ether, closed isocyanate curing agent to the reactor and stir;

   S2. Add acetic acid to the reactor, and disperse at a temperature of 40°C to 50°C for 1 hour;

   S3. Deionized water is added to the reactor, and an emulsion is obtained after emulsification;

   S4. Mix the emulsion with color paste and deionized water to obtain the halogen-free flame-retardant cationic electrodeposition coating.
6. A method for preparing a halogen-free flame-retardant cationic electrodeposition coating, characterized in that, before the step S1, the following steps are further included:

   S0.1 Preparation of amino-modified epoxy resin: the basic epoxy resin, bisphenol A, cardanol, and methyl isobutyl ketone are stirred and mixed, then heated to 100 °C, added with dimethylbenzylamine catalyst, and then heated to 180 °C -190°C for 20 minutes, then the temperature was lowered to 140-150°C for 2 hours. When the temperature was lowered to 100°C, methyl isobutyl ketone was added to mix, and the temperature was maintained at 90-95°C. N-methylethanolamine was added. and ketimine, heat up to 110-120°C for 3 hours, add ethylene glycol butyl ether, cool down to 90°C, and disperse for 20min to obtain the amino-modified epoxy resin;

   S0.2 Preparation of bisphenol A polyoxyethylene ether phosphate: at a temperature of 45-50 °C, add pentaerythritol dropwise to the mixture of phosphorus oxychloride and acetonitrile, raise the temperature to 55-60 °C and keep it for 30 minutes, add bisphenol The phenol A polyoxyethylene ether and the catalyst are raised to the reflux temperature for 3 hours and reacted for 3 hours, filtered and distilled to obtain the bisphenol A polyoxyethylene ether phosphate;

   S0.3 Prepare blocked isocyanate curing agent.

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