A flame-retardant acrylate emulsion for waterborne coatings and its preparation method

Abstract

The present invention relates to the technical field of waterborne coatings, and specifically relates to a flame-retardant acrylate emulsion for waterborne coatings and a preparation method thereof, as well as a waterborne flame-retardant coating prepared by using the flame-retardant acrylate emulsion. The present invention first prepares a phosphorus-containing acrylate monomer and a urea-based acrylate monomer, and then, by using an in-situ polymerization method, copolymerizes them with other acrylate monomers to obtain an acrylate emulsion for waterborne coatings with excellent flame-retardant properties. When added to a coating formulation, the prepared waterborne flame-retardant coating has excellent flame retardancy and impact resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of waterborne coatings, and particularly to a flame-retardant acrylate emulsion for waterborne coatings and a preparation method thereof. Background Art

[0002] Waterborne coatings, also known as water-based paints or waterborne paints, are a type of coatings with water as the main solvent. Since the use of solvents is avoided or reduced, and VOC emissions are reduced, they are a type of green and environmentally friendly coatings. Waterborne coatings include water-dispersed type, water-dilutable type, water-soluble type, etc. In the world coating market, the total output value of waterborne coatings accounts for more than 50%, and the output accounts for more than 60%, and the market is still growing continuously.

[0003] Waterborne coatings can be divided into four types according to the different waterborne resins used to synthesize the coatings, namely acrylate coatings, acetate coatings, epoxy coatings, and polyurethane coatings. Among them, waterborne acrylate resin coatings are the main varieties, with characteristics such as light resistance, weather resistance, heat resistance, etc., and are light in color, have good leveling properties, and good workability, and are widely used in industries such as automobiles, building materials, and home furnishings. Although waterborne acrylate coatings have many advantages, they also have disadvantages such as long drying time, easy to become sticky at high temperatures, easy to become brittle at low temperatures, and flammable by themselves.

[0004] For the flame-retardant modification of waterborne acrylate coatings, usually the method of adding external flame retardants is used. The types of flame retardants include halogen-based flame retardants, filled flame retardants, and intumescent flame retardants. Halogen-based flame retardants are a type of flame retardants containing halogen elements and using halogen elements to play a flame-retardant role. The flame-retardant mechanism includes blocking heat transfer, terminating chain reactions, cutting off heat sources, etc. However, due to the easy generation of harmful substances such as dioxins during the flame-retardant process of halogen-based flame retardants, their use has been restricted. Filled flame retardants include magnesium hydroxide, aluminum hydroxide, etc., and release bound water when decomposed by heat during combustion, absorbing a large amount of latent heat to reduce the temperature of the filled material in the flame, thereby achieving a flame-retardant effect. Intumescent flame retardants, also known as nitrogen-phosphorus-based flame retardants, with phosphorus and nitrogen as the main flame-retardant components, are a new type of environmentally friendly flame retardant without halogen that integrates a carbon source, an acid source, and a gas source. When heated, this type of flame retardant can produce a phosphorus-nitrogen synergistic flame-retardant effect within the molecule, and will form a carbonaceous foam layer on the surface of the plastic during combustion, thereby achieving effects such as heat insulation, oxygen isolation, smoke suppression, and anti-dripping.

[0005] In-situ flame-retardant modification is a flame-retardant modification method developed in recent years. This method is different from the previous method of adding external flame retardants. Instead, flame-retardant matrices such as phosphorus and nitrogen are embedded into acrylate monomers, and in-situ polymerization forms acrylate polymers, which are significantly superior to the previous flame-retardant methods of adding external flame retardants in terms of flame retardancy and durability. Summary of the Invention

[0006] To solve the above technical problems, based on previous research, the present invention first prepares a phosphorus-containing acrylate monomer and a urea-based acrylate monomer. Then, by means of in-situ polymerization, they are copolymerized with other acrylate monomers to obtain an acrylate emulsion for waterborne coatings with excellent flame retardancy. Adding it to the coating formulation, the prepared waterborne flame retardant coating has excellent flame retardancy and impact resistance. The present invention also studies the influence of the polymerization method on the flame retardancy. Through research, it is proved that by using the seed emulsion synthesis method and using the phosphorus-containing acrylate monomer and the urea-based acrylate monomer as the shell raw materials, the obtained core-shell structured acrylate emulsion can further improve the flame retardancy of the acrylate emulsion.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A flame retardant acrylate emulsion for waterborne coatings, which is composed of the following raw materials in parts by weight: 40 parts of methyl methacrylate, 10 - 20 parts of ethyl acrylate, 5 - 10 parts of isooctyl acrylate, 5 - 8 parts of hydroxyethyl acrylate, 8 - 12 parts of phosphorus-containing acrylate monomer, 4 - 10 parts of urea-based acrylate monomer, 4 - 7 parts of initiator, 3 - 6 parts of emulsifier, and 50 - 80 parts of deionized water;

[0009] The emulsifier includes 1 - 3 parts of fatty alcohol polyoxyethylene ether and 2 - 3 parts of sodium dodecyl sulfate;

[0010] The initiator includes one or a combination of two or more of ammonium persulfate, sodium persulfate, and potassium persulfate.

[0011] The preparation method of the phosphorus-containing acrylate monomer is as follows:

[0012] Add phosphorus oxychloride and hydroxyethyl acrylate to a stirring device, then add an appropriate amount of toluene, introduce nitrogen to discharge air, lower the system temperature to 0 °C, stir and react for 2 - 3 h, then raise the temperature to room temperature and react for 10 - 12 h. After spinning the solution dry using a rotary evaporator, the phosphorus-containing acrylate monomer is obtained.

[0013] The reaction equation of phosphorus oxychloride and hydroxyethyl acrylate is as follows:

[0014]

[0015] The molar ratio of phosphorus oxychloride to hydroxyethyl acrylate is 1:3.

[0016] The preparation method of the urea-based acrylate monomer is as follows:

[0017] Add p-trifluoromethylaniline and ethyl 2-isocyanatoacrylate to a stirring device, then add an appropriate amount of tetrahydrofuran to dissolve. Introduce nitrogen, lower the temperature of the system to 0 °C, and stir and react for 4 - 6 h. Then raise the temperature to room temperature and react for 10 - 12 h. After rotary evaporation to dry the solution, a ureidoacrylate monomer is obtained.

[0018] The reaction equation of p-trifluoromethylaniline and ethyl 2-isocyanatoacrylate is as follows:

[0019]

[0020] The molar ratio of p-trifluoromethylaniline to ethyl 2-isocyanatoacrylate is 1:1.

[0021] The dosage ratio of the phosphorus-containing acrylate monomer to the ureidoacrylate monomer is 3:1 - 2.

[0022] The preparation method of a flame-retardant acrylate emulsion for waterborne coatings includes the following steps:

[0023] (1) Prepare the seed emulsion: Add 1 - 3 parts of fatty alcohol polyoxyethylene ether, 2 - 3 parts of sodium dodecyl sulfate, and 50 - 80 parts of deionized water to a reaction kettle. After stirring and dissolving, add 3 - 5 parts of an initiator, raise the temperature to 60 - 80 °C, and then start to dropwise add a mixed liquid composed of 40 parts of methyl methacrylate, 10 - 20 parts of ethyl acrylate, 5 - 10 parts of isooctyl acrylate, and 5 - 8 parts of 2-hydroxyethyl acrylate. The dropping time is 1 - 2 h. After the dropping is completed, keep the temperature for reaction, and the reaction time is 1 - 2 h.

[0024] (2) Prepare the core-shell emulsion: Dropwise add a mixed solution containing 1 - 2 parts of an initiator, 8 - 12 parts of a phosphorus-containing acrylate monomer, and 4 - 10 parts of a ureidoacrylate monomer to the above seed emulsion. The dropping time is 1 - 2 h. After the dropping is completed, keep the temperature for reaction for 2 - 3 h, and the reaction temperature is 60 - 80 °C to obtain a core-shell structured emulsion. Add ammonia water to the emulsion prepared above, adjust the pH value to 7 - 10, filter and discharge to obtain a flame-retardant acrylate emulsion for waterborne coatings.

[0025] Further, the initiators in step (1) and step (2) are of the same type.

[0026] Another object of the present invention is to provide a waterborne coating prepared by using the flame-retardant acrylate emulsion. The waterborne coating includes the following components in parts by weight: 100 parts of the flame-retardant acrylate emulsion, 10 - 20 parts of a pigment, 10 - 30 parts of a filler, 1 - 3 parts of a dispersant, 2 - 5 parts of a thickener, and 2 - 5 parts of an antifoaming agent.

[0027] The preparation process of the waterborne coating is as follows:

[0028] By weight parts, 100 parts of flame-retardant acrylate emulsion, 10 - 20 parts of pigment, 10 - 30 parts of filler, 1 - 3 parts of dispersant, 2 - 5 parts of thickener, and 2 - 5 parts of defoamer are mixed evenly to obtain the flame-retardant acrylate coating.

[0029] The pigment is one or a combination of titanium dioxide, iron red, iron yellow, carbon black, ultramarine, lead chromate yellow, phthalocyanine blue, phthalocyanine green, etc.;

[0030] The filler is one or a combination of calcium carbonate, talcum powder, mica powder, kaolin, quartz sand, barium sulfate, etc.;

[0031] The dispersant is one or a combination of DisponerW-511, W-920, Dispex AA4140, etc.

[0032] The thickener is one or a combination of TEGO3000 and TEGO3030;

[0033] The defoamer is one or a combination of DefomW-082, XP-502E, BYK-024, etc.

[0034] Based on actual needs, the present invention can also add commonly used additives in the art, such as cross-linking agents, wetting agents, antioxidants, film-forming agents, solvents, etc.

[0035] For the cross-linking agent, commonly used types of cross-linking agents in the art can be used, such as polyisocyanates, epoxy cross-linking agents, aziridine cross-linking agents, etc. Based on the addition of a phosphorus-containing acrylate monomer with a branched structure in the synthesis raw materials of the flame-retardant acrylate emulsion of this application, the use of the cross-linking agent can also be omitted as appropriate.

[0036] For the wetting agent, anionic wetting agents, cationic wetting agents, non-ionic wetting agents, etc. can be used. The anionic wetting agents include sulfate esters, sulfonates, phosphate esters, etc.;

[0037] The cationic wetting agents mainly include quaternary ammonium salts, amine salts, etc.;

[0038] The non-ionic wetting agents mainly include polyoxyethylene ethers, polyoxyethylene esters, polyoxyethylene amines, etc.

[0039] The antioxidants include phosphate ester antioxidants and hindered phenol antioxidants, etc.

[0040] The film-forming agents include alcohols, alcohol esters, alcohol ethers, alcohol ether esters, etc.

[0041] The solvents include toluene, ethanol, propylene glycol methyl ether, dipropylene glycol butyl ether, etc.

[0042] As long as the above-mentioned auxiliaries do not affect the conventional properties of the waterborne coating, they can be used in an appropriate amount.

[0043] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0044] The flame-retardant acrylate emulsion of the present invention uses phosphorus oxychloride and 2-hydroxyethyl acrylate to react according to a molar ratio of 1:3 to obtain a phosphorus-containing acrylate monomer with a branched structure. This monomer has a branched structure, which can improve the crosslinking degree of the synthesized acrylate emulsion, and further improve its mechanical properties. In addition, the present invention uses p-trifluoromethylaniline and 2-isocyanatoethyl acrylate to react according to a molar ratio of 1:1 to obtain a ureido acrylate monomer. This monomer has a high nitrogen content and is compounded with the synthesized phosphorus-containing acrylate monomer to form a nitrogen-phosphorus flame-retardant system, enhancing the charring property of the acrylate paint film during combustion, reducing the contact between the internal material and oxygen, and inhibiting combustion. The present invention adopts a synthesis process of first preparing a seed emulsion and then preparing a core-shell structure acrylate. The outside of the core-shell structure acrylate emulsion particles formed by the phosphorus-containing acrylate monomer and the ureido acrylate monomer further improves the flame retardancy of the synthesized acrylate emulsion, and the ureido acrylate monomer also contains a fluorine group, which can further improve the waterproof property of the acrylate emulsion. Specific Embodiments

[0045] The technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments. However, those skilled in the art will understand that the following described embodiments are some embodiments of the present invention, not all embodiments, and are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention. Those not specified in the embodiments are carried out under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments not specified by the manufacturer are all conventional products that can be obtained through commercial purchase.

[0046] Synthesis Example 1

[0047] Preparation of phosphorus-containing acrylate monomer:

[0048] 15.3 g (0.1 mol) of phosphorus oxychloride and 34.8 g (0.3 mol) of 2-hydroxyethyl acrylate were added to a four-necked flask equipped with a stirring device. Then 300 ml of toluene was added, and nitrogen was introduced to expel air. The temperature of the system was lowered to 0 °C using an ice bath, and the reaction was stirred for 2.5 h. Then the temperature was raised to room temperature and the reaction was carried out for 12 h. After the solution was dried by rotary evaporation, a phosphorus-containing acrylate monomer was obtained, denoted as P1.

[0049] Synthesis Example 2

[0050] Preparation of ureido acrylate monomer:

[0051] Add 16.1 g (0.1 mol) of p-trifluoromethylaniline and 14.1 g (0.1 mol) of 2-isocyanatoethyl acrylate into a four-necked flask equipped with a stirring device. Then add 300 ml of tetrahydrofuran to dissolve, introduce nitrogen, cool the system temperature to 0 °C using an ice bath, stir and react for 5 h. Then raise the temperature to room temperature and react for 12 h. After rotary evaporation to dry the solution, the ureido acrylate monomer is obtained, denoted as P2.

[0052] Example 1

[0053] A flame-retardant acrylate emulsion for waterborne coatings is composed of the following raw materials in parts by weight: 40 parts of methyl methacrylate, 10 parts of ethyl acrylate, 8 parts of isooctyl acrylate, 6 parts of hydroxyethyl acrylate, 9 parts of phosphorus-containing acrylate monomer P1, 6 parts of ureido acrylate monomer P2, 4 parts of ammonium persulfate, 2 parts of fatty alcohol polyoxyethylene ether, 2 parts of sodium dodecyl sulfate, and 60 parts of deionized water;

[0054] The preparation process of the flame-retardant acrylate emulsion for waterborne coatings is as follows:

[0055] (1) Preparation of seed emulsion: Add 2 parts of fatty alcohol polyoxyethylene ether, 2 parts of sodium dodecyl sulfate, and 60 parts of deionized water into a reaction kettle, stir and dissolve, then add 3 parts of ammonium persulfate, heat up to 65 °C, and then start to dropwise add a mixed liquid composed of 40 parts of methyl methacrylate, 10 parts of ethyl acrylate, 8 parts of isooctyl acrylate, and 6 parts of hydroxyethyl acrylate. The dropping time is 1.5 h. After dropping, keep the temperature for reaction, and the reaction time is 2 h.

[0056] (2) Preparation of core-shell emulsion: Dropwise add a mixed solution containing 1 part of ammonium persulfate, 9 parts of phosphorus-containing acrylate monomer P1, and 6 parts of ureido acrylate monomer P2 into the above seed emulsion. The dropping time is 1 h. After dropping, keep the temperature for reaction for 2.5 h at 70 °C to obtain a core-shell structured emulsion. Add ammonia water to the emulsion prepared above, adjust the pH value to 8, filter and discharge to obtain the flame-retardant acrylate emulsion for waterborne coatings.

[0057] Example 2

[0058] A flame-retardant acrylate emulsion for waterborne coatings is composed of the following raw materials in parts by weight: 40 parts of methyl methacrylate, 10 parts of ethyl acrylate, 8 parts of isooctyl acrylate, 6 parts of hydroxyethyl acrylate, 12 parts of phosphorus-containing acrylate monomer P1, 4 parts of ureido acrylate monomer P2, 4 parts of ammonium persulfate, 2 parts of fatty alcohol polyoxyethylene ether, 2 parts of sodium dodecyl sulfate, and 60 parts of deionized water;

[0059] The preparation process of the flame-retardant acrylate emulsion for waterborne coatings is as follows:

[0060] (1) Preparation of seed emulsion: Add 2 parts of fatty alcohol polyoxyethylene ether, 2 parts of sodium dodecyl sulfate, and 60 parts of deionized water to the reaction kettle. After stirring and dissolving, add 3 parts of ammonium persulfate, heat up to 65 °C, and then start dropping a mixed liquid composed of 40 parts of methyl methacrylate, 10 parts of ethyl acrylate, 8 parts of isooctyl acrylate, and 6 parts of 2-hydroxyethyl acrylate. The dropping time is 1.5 h. After the dropping is completed, keep the temperature for reaction, and the reaction time is 2 h.

[0061] (2) Preparation of core-shell emulsion: Drop a mixed solution containing 1 part of ammonium persulfate, 12 parts of phosphorus-containing acrylate monomer P1, and 4 parts of urea-containing acrylate monomer P2 into the above-mentioned seed emulsion. The dropping time is 1 h. After the dropping is completed, keep the temperature for reaction for 2.5 h at a reaction temperature of 70 °C to obtain a core-shell structured emulsion. Add ammonia water to the emulsion prepared above, adjust the pH value to 8, filter and discharge to obtain the flame-retardant acrylate emulsion for waterborne coatings.

[0062] Example 3

[0063] A flame-retardant acrylate emulsion for waterborne coatings is composed of the following raw materials in parts by weight: 40 parts of methyl methacrylate, 10 parts of ethyl acrylate, 8 parts of isooctyl acrylate, 6 parts of 2-hydroxyethyl acrylate, 12 parts of phosphorus-containing acrylate monomer P1, 8 parts of urea-containing acrylate monomer P2, 4 parts of ammonium persulfate, 1 part of fatty alcohol polyoxyethylene ether, 3 parts of sodium dodecyl sulfate, and 70 parts of deionized water;

[0064] The preparation process of the flame-retardant acrylate emulsion for waterborne coatings is as follows:

[0065] (1) Preparation of seed emulsion: Add 1 part of fatty alcohol polyoxyethylene ether, 3 parts of sodium dodecyl sulfate, and 70 parts of deionized water to the reaction kettle. After stirring and dissolving, add 3 parts of ammonium persulfate, heat up to 70 °C, and then start dropping a mixed liquid composed of 40 parts of methyl methacrylate, 10 parts of ethyl acrylate, 8 parts of isooctyl acrylate, and 6 parts of 2-hydroxyethyl acrylate. The dropping time is 1.5 h. After the dropping is completed, keep the temperature for reaction, and the reaction time is 2 h.

[0066] (2) Preparation of core-shell emulsion: Drop a mixed solution containing 1 part of ammonium persulfate, 12 parts of phosphorus-containing acrylate monomer P1, and 8 parts of urea-containing acrylate monomer P2 into the above-mentioned seed emulsion. The dropping time is 1 h. After the dropping is completed, keep the temperature for reaction for 2.5 h at a reaction temperature of 75 °C to obtain a core-shell structured emulsion. Add ammonia water to the emulsion prepared above, adjust the pH value to 8, filter and discharge to obtain the flame-retardant acrylate emulsion for waterborne coatings.

[0067] Comparative Example 1

[0068] A flame-retardant acrylate emulsion for waterborne coatings is composed of the following raw materials in parts by weight: 40 parts of methyl methacrylate, 10 parts of ethyl acrylate, 8 parts of isooctyl acrylate, 6 parts of hydroxyethyl acrylate, 15 parts of a phosphorus-containing acrylate monomer P1, 4 parts of ammonium persulfate, 2 parts of fatty alcohol polyoxyethylene ether, 2 parts of sodium dodecyl sulfate, and 60 parts of deionized water;

[0069] The preparation process of the flame-retardant acrylate emulsion for waterborne coatings is as follows:

[0070] (1) Preparation of seed emulsion: Add 2 parts of fatty alcohol polyoxyethylene ether, 2 parts of sodium dodecyl sulfate, and 60 parts of deionized water to a reaction kettle. After stirring and dissolving, add 3 parts of ammonium persulfate, heat up to 65 °C, and then start dropping a mixed liquid composed of 40 parts of methyl methacrylate, 10 parts of ethyl acrylate, 8 parts of isooctyl acrylate, and 6 parts of hydroxyethyl acrylate. The dropping time is 1.5 h. After the dropping is completed, keep the temperature for reaction, and the reaction time is 2 h.

[0071] (2) Preparation of core-shell emulsion: Drop a mixed solution containing 1 part of ammonium persulfate and 15 parts of a urea-containing acrylate monomer P2 into the above seed emulsion. The dropping time is 1 h. After the dropping is completed, keep the temperature for reaction for 2.5 h, and the reaction temperature is 70 °C to obtain a core-shell structured emulsion. Add ammonia water to the emulsion prepared above, adjust the pH value to 8, filter and discharge to obtain the flame-retardant acrylate emulsion for waterborne coatings.

[0072] Comparative Example 2

[0073] A flame-retardant acrylate emulsion for waterborne coatings is composed of the following raw materials in parts by weight: 40 parts of methyl methacrylate, 10 parts of ethyl acrylate, 8 parts of isooctyl acrylate, 6 parts of hydroxyethyl acrylate, 15 parts of a urea-containing acrylate monomer P2, 4 parts of ammonium persulfate, 2 parts of fatty alcohol polyoxyethylene ether, 2 parts of sodium dodecyl sulfate, and 60 parts of deionized water;

[0074] The preparation process of the flame-retardant acrylate emulsion for waterborne coatings is as follows:

[0075] (1) Preparation of seed emulsion: Add 2 parts of fatty alcohol polyoxyethylene ether, 2 parts of sodium dodecyl sulfate, and 60 parts of deionized water to a reaction kettle. After stirring and dissolving, add 3 parts of ammonium persulfate, heat up to 65 °C, and then start dropping a mixed liquid composed of 40 parts of methyl methacrylate, 10 parts of ethyl acrylate, 8 parts of isooctyl acrylate, and 6 parts of hydroxyethyl acrylate. The dropping time is 1.5 h. After the dropping is completed, keep the temperature for reaction, and the reaction time is 2 h.

[0076] (2) Preparation of core-shell emulsion: A mixed solution containing 1 part of ammonium persulfate and 15 parts of ureido acrylate monomer P2 was added dropwise to the above seed emulsion over 1 h. After the addition was completed, the mixture was kept at a reaction temperature of 70 °C for 2.5 h to obtain a core-shell structured emulsion. Ammonia water was added to the emulsion prepared above to adjust the pH value to 8, and then the mixture was filtered and discharged to obtain a flame-retardant acrylate emulsion for waterborne coatings.

[0077] Comparative Example 3

[0078] A flame-retardant acrylate emulsion for waterborne coatings is composed of the following raw materials in parts by weight: 40 parts of methyl methacrylate, 10 parts of ethyl acrylate, 8 parts of isooctyl acrylate, 6 parts of hydroxyethyl acrylate, 12 parts of phosphorus-containing acrylate monomer P1, 3 parts of ureido acrylate monomer P2, 4 parts of ammonium persulfate, 2 parts of fatty alcohol polyoxyethylene ether, 2 parts of sodium dodecyl sulfate, and 60 parts of deionized water.

[0079] The preparation process of the flame-retardant acrylate emulsion for waterborne coatings is as follows:

[0080] (1) Preparation of seed emulsion: 2 parts of fatty alcohol polyoxyethylene ether, 2 parts of sodium dodecyl sulfate, and 60 parts of deionized water were added to a reaction kettle. After stirring and dissolving, 3 parts of ammonium persulfate were added, and the temperature was raised to 65 °C. Then, a mixed liquid composed of 40 parts of methyl methacrylate, 10 parts of ethyl acrylate, 8 parts of isooctyl acrylate, and 6 parts of hydroxyethyl acrylate was added dropwise over 1.5 h. After the addition was completed, the mixture was kept at a reaction temperature for 2 h.

[0081] (2) Preparation of core-shell emulsion: A mixed solution containing 1 part of ammonium persulfate, 12 parts of phosphorus-containing acrylate monomer P1, and 3 parts of ureido acrylate monomer P2 was added dropwise to the above seed emulsion over 1 h. After the addition was completed, the mixture was kept at a reaction temperature of 70 °C for 2.5 h to obtain a core-shell structured emulsion. Ammonia water was added to the emulsion prepared above to adjust the pH value to 8, and then the mixture was filtered and discharged to obtain a flame-retardant acrylate emulsion for waterborne coatings.

[0082] Comparative Example 4

[0083] A flame-retardant acrylate emulsion for waterborne coatings is composed of the following raw materials in parts by weight: 40 parts of methyl methacrylate, 10 parts of ethyl acrylate, 8 parts of isooctyl acrylate, 6 parts of hydroxyethyl acrylate, 8 parts of phosphorus-containing acrylate monomer P1, 8 parts of ureido acrylate monomer P2, 4 parts of ammonium persulfate, 2 parts of fatty alcohol polyoxyethylene ether, 2 parts of sodium dodecyl sulfate, and 60 parts of deionized water.

[0084] The preparation process of the flame-retardant acrylate emulsion for coatings is as follows:

[0085] (1) Preparation of seed emulsion: Add 2 parts of fatty alcohol polyoxyethylene ether, 2 parts of sodium dodecyl sulfate, and 60 parts of deionized water into a reaction kettle. After stirring and dissolving, add 3 parts of ammonium persulfate, heat up to 65 °C, and then start to dropwise add a mixed liquid composed of 40 parts of methyl methacrylate, 10 parts of ethyl acrylate, 8 parts of isooctyl acrylate, and 6 parts of 2-hydroxyethyl acrylate. The dropping time is 1.5 h. After the dropping is completed, keep the temperature for reaction, and the reaction time is 2 h.

[0086] (2) Preparation of core-shell emulsion: Dropwise add a mixed solution containing 1 part of ammonium persulfate, 8 parts of phosphorus-containing acrylate monomer P1, and 8 parts of ureido-containing acrylate monomer P2 into the above-mentioned seed emulsion. The dropping time is 1 h. After the dropping is completed, keep the temperature for reaction for 2.5 h at a reaction temperature of 70 °C to obtain a core-shell structured emulsion. Add ammonia water to the emulsion prepared above, adjust the pH value to 8, filter and discharge to obtain a flame-retardant acrylate emulsion for waterborne coatings.

[0087] Comparative Example 5

[0088] A flame-retardant acrylate emulsion for waterborne coatings is composed of the following raw materials in parts by weight: 40 parts of methyl methacrylate, 10 parts of ethyl acrylate, 8 parts of isooctyl acrylate, 6 parts of 2-hydroxyethyl acrylate, 9 parts of phosphorus-containing acrylate monomer P1, 6 parts of ureido-containing acrylate monomer P2, 4 parts of ammonium persulfate, 2 parts of fatty alcohol polyoxyethylene ether, 2 parts of sodium dodecyl sulfate, and 60 parts of deionized water;

[0089] The preparation process of the flame-retardant acrylate emulsion for waterborne coatings is as follows:

[0090] Add 2 parts of fatty alcohol polyoxyethylene ether, 2 parts of sodium dodecyl sulfate, and 60 parts of deionized water into a reaction kettle. After stirring and dissolving, add 4 parts of ammonium persulfate, heat up to 65 °C, and then start to dropwise add a mixed liquid composed of 40 parts of methyl methacrylate, 10 parts of ethyl acrylate, 8 parts of isooctyl acrylate, 6 parts of 2-hydroxyethyl acrylate, 9 parts of phosphorus-containing acrylate monomer P1, and 6 parts of ureido-containing acrylate monomer P2. The dropping time is 1.5 h. After the dropping is completed, keep the temperature for reaction, and the reaction time is 2 h. Add ammonia water to the emulsion prepared above, adjust the pH value to 8, filter and discharge to obtain a flame-retardant acrylate emulsion for waterborne coatings.

[0091] Application Example 1

[0092] By weight, mix 100 parts of the flame-retardant acrylate emulsion obtained in Example 1, 15 parts of titanium dioxide, 18 parts of calcium carbonate, 2 parts of DisponerW-511, 3 parts of TEGO3000, and 2 parts of DefomW-082 to obtain a waterborne flame-retardant acrylate coating S1.

[0093] Application Example 2

[0094] By weight parts, 100 parts of the flame-retardant acrylate emulsion obtained in Example 2, 15 parts of titanium dioxide, 18 parts of calcium carbonate, 2 parts of DisponerW-511, 3 parts of TEGO3000, and 2 parts of DefomW-082 were mixed evenly to prepare the waterborne flame-retardant acrylate coating S2.

[0095] Application Example 3

[0096] By weight parts, 100 parts of the flame-retardant acrylate emulsion obtained in Example 3, 15 parts of titanium dioxide, 18 parts of calcium carbonate, 2 parts of DisponerW-511, 3 parts of TEGO3000, and 2 parts of DefomW-082 were mixed evenly to prepare the waterborne flame-retardant acrylate coating S3.

[0097] Comparative Application Example 1

[0098] By weight parts, 100 parts of the flame-retardant acrylate emulsion obtained in Comparative Example 1, 15 parts of titanium dioxide, 18 parts of calcium carbonate, 2 parts of DisponerW-511, 3 parts of TEGO3000, and 2 parts of DefomW-082 were mixed evenly to prepare the waterborne flame-retardant acrylate coating W1.

[0099] Comparative Application Example 2

[0100] By weight parts, 100 parts of the flame-retardant acrylate emulsion obtained in Comparative Example 2, 15 parts of titanium dioxide, 18 parts of calcium carbonate, 2 parts of DisponerW-511, 3 parts of TEGO3000, and 2 parts of DefomW-082 were mixed evenly to prepare the waterborne flame-retardant acrylate coating W2.

[0101] Comparative Application Example 3

[0102] By weight parts, 100 parts of the flame-retardant acrylate emulsion obtained in Comparative Example 3, 15 parts of titanium dioxide, 18 parts of calcium carbonate, 2 parts of DisponerW-511, 3 parts of TEGO3000, and 2 parts of DefomW-082 were mixed evenly to prepare the waterborne flame-retardant acrylate coating W3.

[0103] Comparative Application Example 4

[0104] By weight parts, 100 parts of the flame-retardant acrylate emulsion obtained in Comparative Example 4, 15 parts of titanium dioxide, 18 parts of calcium carbonate, 2 parts of DisponerW-511, 3 parts of TEGO3000, and 2 parts of DefomW-082 were mixed evenly to prepare the waterborne flame-retardant acrylate coating W4.

[0105] Comparative Application Example 5

[0106] By weight, 100 parts of the flame-retardant acrylic emulsion obtained in Comparative Example 5, 15 parts of titanium dioxide, 18 parts of calcium carbonate, 2 parts of Disponer W-511, 3 parts of TEGO 3000, and 2 parts of Defom W-082 were mixed to prepare a water-based flame-retardant acrylic coating W5.

[0107] Performance Testing

[0108] The obtained water-based flame-retardant acrylic paint was used to prepare the required samples according to the standard. The flame retardant performance of the paint film was tested by an oxygen index tester according to GB / T2406.1-2008. The impact resistance was tested by a paint film impactor according to the GB / T1732-93 method. The hardness was tested by a pencil hardness tester according to the GB / T6739-2022 method.

[0109] Table 1 Test results of water-based flame-retardant acrylic coatings obtained in various application examples and comparative application examples

[0110]

[0111] By comparing application example S1 with comparative application examples W1-W4, it can be seen that the combination of the phosphorus-containing acrylate monomer synthesized in the present application and the urea-containing acrylate monomer has a significant improvement in flame retardancy, impact resistance and hardness compared to the use of the phosphorus-containing acrylate monomer or the urea-containing acrylate monomer alone. And when the mass ratio of the phosphorus-containing acrylate monomer to the urea-containing acrylate monomer is within a limited range, the flame retardancy, impact resistance and pencil hardness of the obtained coating are optimal.

[0112] By comparing application example S1 with comparative application example W5, it can be seen that the preparation process of the flame-retardant acrylic emulsion of the present application is adopted. The seed emulsion is prepared first, and then the core-shell structure acrylic ester is prepared, and the outer part of the core-shell structure acrylic emulsion particles formed by the phosphorus-containing acrylic ester monomer and the urea-containing acrylic ester monomer is further improved in flame retardancy, impact resistance and hardness of the synthesized acrylic emulsion.

[0113] The above contents are merely examples and explanations of the concept of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the defined scope, they should all fall within the protection scope of the present invention.

Claims

1. A flame retardant acrylic emulsion for water-based coatings, characterized in that: The invention is composed of the following raw materials in parts by weight: 40 parts of methyl methacrylate, 10-20 parts of ethyl acrylate, 5-10 parts of isooctyl acrylate, 5-8 parts of hydroxyethyl acrylate, 8-12 parts of phosphorus-containing acrylate monomer, 4-10 parts of urea-containing acrylate monomer, 4-7 parts of initiator, 3-6 parts of emulsifier, and 50-80 parts of deionized water, wherein the ratio of the phosphorus-containing acrylate monomer to the urea-containing acrylate monomer is 3:1-2; the emulsifier comprises 1-3 parts of fatty alcohol polyoxyethylene ether and 2-3 parts of sodium lauryl sulfate; The preparation method of the urea-containing acrylate monomer is as follows: adding trifluoromethylaniline and 2-isocyanate ethyl acrylate to a stirring device, then adding an appropriate amount of tetrahydrofuran to dissolve, introducing nitrogen, lowering the system temperature to 0°C, stirring for reaction for 4-6 hours, then heating to room temperature for reaction for 10-12 hours, and using a rotary evaporator to spin-dry the solution to obtain a urea-containing acrylate monomer; the phosphorus-containing acrylate monomer is obtained by reacting phosphorus oxychloride and hydroxyethyl acrylate; the preparation method of the flame-retardant acrylate emulsion for water-based coatings comprises the following steps: Step 1: Prepare seed emulsion: add 1-3 parts of fatty alcohol polyoxyethylene ether, 2-3 parts of sodium lauryl sulfate, and 50-80 parts of deionized water to a reactor, stir and dissolve, add 3-5 parts of initiator, heat to 60-80°C, then start to drop a mixed liquid consisting of 40 parts of methyl methacrylate, 10-20 parts of ethyl acrylate, 5-10 parts of isooctyl acrylate, and 5-8 parts of hydroxyethyl acrylate, the dropping time is 1-2h, and after the dropping is completed, keep warm for reaction, the reaction time is 1-2h; Step 2: Prepare a core-shell emulsion: add a mixed solution containing 1-2 parts of an initiator, 8-12 parts of a phosphorus-containing acrylate monomer and 4-10 parts of a urea-containing acrylate monomer to the above-mentioned seed emulsion, the addition time is 1-2 hours, and after the addition is completed, the reaction is kept warm for 2-3 hours at a reaction temperature of 60-80°C to obtain a core-shell structure emulsion, add ammonia water to the emulsion prepared above, adjust the pH value to 7-10, filter the material, and obtain a flame-retardant acrylate emulsion for water-based coatings.

2. A flame-retardant acrylic emulsion for water-based coatings as claimed in claim 1, characterized in that: The initiator is one or a combination of two or more of ammonium persulfate, sodium persulfate and potassium persulfate.

3. The flame-retardant acrylic emulsion for water-based coatings according to claim 1, characterized in that: The preparation method of the phosphorus-containing acrylate monomer is as follows: phosphorus oxychloride and hydroxyethyl acrylate are added to a stirring device, then an appropriate amount of toluene is added, nitrogen is introduced to exhaust the air, the system temperature is lowered to 0°C, stirred for reaction for 2-3 hours, then the temperature is raised to room temperature for reaction for 10-12 hours, and the solution is dried by a rotary evaporator to obtain the phosphorus-containing acrylate monomer.

4. A flame retardant acrylic emulsion for water-based coatings as claimed in claim 3, characterized in that: The molar ratio of phosphorus oxychloride to hydroxyethyl acrylate is 1:

3.

5. The flame-retardant acrylic emulsion for water-based coatings according to claim 1, characterized in that: The molar ratio of p-trifluoromethylaniline to 2-ethyl isocyanate acrylate is 1:

1.

6. The flame-retardant acrylic emulsion for water-based coatings according to claim 1, characterized in that: The initiators in step 1 and step 2 are the same type of initiators.

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