Flame-retardant coating and preparation method thereof

Abstract

The invention relates to the technical field of flame retardance, and discloses a flame-retardant coating and a preparation method thereof.The flame-retardant coating is obtained by adding phenolic resin, polycarbonate, phosphorus-containing modified phenolic resin, boric acid-containing benzoxazine, an organic silicon resin defoaming agent, a propylene glycol film-forming agent and water into a stirrer and stirring. The flame-retardant coating contains a large amount of anacardol, long chains in the anacardol can also be crosslinked to form a net-shaped structure, a net-shaped carbon skeleton structure is formed under high-temperature carbonization, degradation products are inhibited during combustion, and the flame-retardant coating has good fire resistance; wherein oxazolidinone generated by reaction of an epoxy group of epoxidized phenolic resin and an isocyanate group of hexamethylene diisocyanate is a heterocyclic ring with very high heat resistance and also plays a role in synergistic fire resistance; the flame-retardant coating contains a large amount of phosphorus elements, sulfur elements and nitrogen elements, has a good flame-retardant effect, and achieves a synergistic flame-retardant effect.

Description

Technical Field

[0001] The invention relates to the technical field of flame retardancy, in particular to a flame retardant coating and a preparation method thereof. Background Art

[0002] With the development of society, more and more coatings are used, and they are widely used in homes and offices. However, in the event of a fire, most coatings burn and produce toxic gases, which can cause harm to the body. Therefore, how to avoid this phenomenon is the key to solving the problem. For example, the document "Research Progress of New Phenolic Resin-Benzoxazine" reports that benzoxazine resin has good flame retardancy. It is used in the present invention together with other flame retardants to prepare a flame retardant coating. Summary of the invention

[0003] 1. Technical issues to be resolved In view of the deficiencies of the prior art, the present invention provides a flame retardant coating and a preparation method thereof, which has good fire resistance and flame retardant properties.

[0004] (II) Technical solution To achieve the above object, the present invention provides the following technical solution: a flame retardant coating, comprising the following components by weight: 40-80 parts by weight of phenolic resin, 15-25 parts by weight of polycarbonate, 10-20 parts by weight of phosphorus-modified phenolic resin, 5-12 parts by weight of boric acid-containing benzoxazine, 1-2 parts by weight of silicone resin defoamer, 2-3 parts by weight of propylene glycol film-forming agent, and 8-14 parts by weight of water; The preparation method of the boric acid-containing benzoxazine comprises the following steps: S1. Add 4-aminophenylboronic acid, phenol and formaldehyde to 1,4-dioxane solvent, stir evenly, carry out cyclization reaction, reflux reaction at 90-120° C. for 18-25 hours, and after the reaction, perform vacuum distillation, wash and recrystallize to obtain boric acid-containing benzoxazine.

[0005] Preferably, the preparation method of the phosphorus-modified phenolic resin is: (1) Phenol, formaldehyde and cardanol are added to the reactor in sequence, stirred evenly, and then oxalic acid is added, the temperature is raised to 80-100°C and refluxed for reaction for 3-5 hours, and dehydrated after the reaction to obtain cardanol-modified phenolic resin; (2) mixing the cardanol-modified phenolic resin and epichlorohydrin uniformly, wherein the mass ratio of the cardanol-modified phenolic resin to epichlorohydrin is 1:1.1-1.3, reacting at 75-90° C. for 8-14 hours, and then concentrating under reduced pressure and washing to obtain an epoxidized phenolic resin; (3) adding triallyl phosphate to N,N-dimethylformamide solvent, stirring to dissolve, and then adding 3-(dimethylamino)-1-propanethiol and benzoin dimethyl ether initiator, irradiating with 365 nm ultraviolet light at 40-50 °C for 2-4 h, centrifuging, washing and drying to obtain intermediate 1; (4) adding the intermediate 1, sodium 3-chloro-2-hydroxypropanesulfonate to a reactor filled with N,N-dimethylformamide solvent, introducing nitrogen protection, reacting at 50-80°C for 6-10 hours, and then removing the solvent by rotary evaporation and drying to obtain a hydroxylated phosphate; (5) Add the epoxidized phenolic resin and hexamethylene diisocyanate into a reactor containing N,N-dimethylformamide solvent, stir evenly, continue to add tetramethylammonium chloride catalyst, react at 60-90°C for 15-18h, then add hydroxylated phosphate, react at 90-110°C for 12-16h, and then distill under reduced pressure, filter and dry to obtain phosphorus-modified phenolic resin.

[0006] Preferably, the mass ratio of phenol, formaldehyde, cardanol and oxalic acid in (1) is 1:1.1-1.2:0.8-1.0:0.02-0.05.

[0007] Preferably, the mass ratio of triallyl phosphate, 3-(dimethylamino)-1-propanethiol, and benzoin dimethyl ether initiator in (3) is 1:1.2-1.6:0.01-0.02.

[0008] Preferably, the mass ratio of the intermediate 1 and sodium 3-chloro-2-hydroxypropanesulfonate in (4) is 1:1.5-2.2.

[0009] Preferably, the mass ratio of the epoxidized phenolic resin, hexamethylene diisocyanate, tetramethylammonium chloride catalyst, and hydroxylated phosphate in (5) is 1.2-1.4:1:0.02-0.03:1.1-1.3.

[0010] Preferably, the mass ratio of 4-aminophenylboric acid, phenol and formaldehyde in S1 is 1:1.2-1.3:0.8-1.5.

[0011] Preferably, the method for preparing the flame retardant coating comprises the following steps: adding phenolic resin, polycarbonate, phosphorus-modified phenolic resin, boric acid-containing benzoxazine, silicone resin defoamer, propylene glycol film-forming agent, and water into a stirrer, and then stirring at 900-1000 r / min for 15-18 min to obtain the flame retardant coating.

[0012] 3. Beneficial technical effects Phenolic resin, polycarbonate, phosphorus-modified phenolic resin, boric acid-containing benzoxazine, silicone resin defoamer, propylene glycol film-forming agent and water are added into a stirrer and stirred to obtain a flame retardant coating.

[0013] During the stirring process, the boric acid groups in the boric acid benzoxazine and the phenolic hydroxyl groups in the phenol will react to form a cross-linked network, while increasing the compatibility with the phenolic resin. The flame retardant coating contains a large amount of cardanol, the long chains of which will also be cross-linked into a network structure, and form a network carbon skeleton structure under high-temperature carbonization, which inhibits degradation products during combustion and has good fire resistance; the oxazolidinone generated by the reaction of the epoxy group of the epoxidized phenolic resin and the isocyanate group of hexamethylene diisocyanate is a highly heat-resistant heterocycle, which also plays a synergistic fire-resistant role; the flame retardant coating contains a large amount of phosphorus, sulfur, and nitrogen elements, all of which have good flame retardant effects and synergistic flame retardancy; and the sulfonate groups therein can catalyze the isomerization and cross-linking of polycarbonate into carbon, thereby making the polycarbonate have a higher carbon forming property and making the coating exhibit excellent fire resistance. DETAILED DESCRIPTION Example 1

[0014] (1) Phenol, formaldehyde and cardanol are added to a reactor in sequence, stirred evenly, and then oxalic acid is added, wherein the mass ratio of phenol, formaldehyde, cardanol and oxalic acid is 1:1.1:0.8:0.02, the temperature is raised to 80°C and refluxed for reaction for 3 hours, and dehydrated after the reaction to obtain a cardanol-modified phenolic resin; (2) mixing the cardanol-modified phenolic resin and epichlorohydrin uniformly, wherein the mass ratio of the cardanol-modified phenolic resin to epichlorohydrin is 1:1.1, reacting at 75° C. for 8 h, and then concentrating and washing under reduced pressure to obtain an epoxidized phenolic resin; (3) adding triallyl phosphate to N,N-dimethylformamide solvent, stirring to dissolve, and then continuing to add 3-(dimethylamino)-1-propanethiol and benzoin dimethyl ether initiator, wherein the mass ratio of triallyl phosphate, 3-(dimethylamino)-1-propanethiol and benzoin dimethyl ether initiator is 1:1.2:0.01, irradiating with 365nm ultraviolet light at 40°C for 2h, centrifuging, washing and drying after the end, to obtain intermediate 1; (4) adding the intermediate 1 and sodium 3-chloro-2-hydroxypropanesulfonate to a reactor filled with N,N-dimethylformamide solvent, wherein the mass ratio of the intermediate 1 and sodium 3-chloro-2-hydroxypropanesulfonate is 1:1.5, introducing nitrogen protection, reacting at 50° C. for 6 hours, and then removing the solvent by rotary evaporation and drying to obtain a hydroxylated phosphate; (5) adding epoxidized phenolic resin and hexamethylene diisocyanate into a reactor containing N,N-dimethylformamide solvent, stirring evenly, adding tetramethylammonium chloride catalyst, reacting at 60°C for 15 hours, and then adding hydroxylated phosphate, wherein the mass ratio of epoxidized phenolic resin, hexamethylene diisocyanate, tetramethylammonium chloride catalyst, and hydroxylated phosphate is 1.2:1:0.02:1.1, reacting at 90°C for 12 hours, and then distilling under reduced pressure, filtering and drying to obtain phosphorus-modified phenolic resin; (6) Adding 4-aminophenylboronic acid, phenol and formaldehyde to 1,4-dioxane solvent and stirring evenly, wherein the mass ratio of 4-aminophenylboronic acid, phenol and formaldehyde is 1:1.2:0.8, carrying out cyclization reaction, reflux reaction at 90°C for 18h, and after the reaction, distilling under reduced pressure, washing and recrystallizing to obtain boric acid-containing benzoxazine; (7) 40 parts by weight of phenolic resin, 15 parts by weight of polycarbonate, 10 parts by weight of phosphorus-modified phenolic resin, 5 parts by weight of boric acid-containing benzoxazine, 1 part by weight of silicone resin defoamer, 2 parts by weight of propylene glycol film-forming agent, and 8 parts by weight of water were added into a stirrer, and then stirred at 900 r / min for 15 min to obtain a flame retardant coating. Example 2

[0015] (1) Phenol, formaldehyde and cardanol are added to a reactor in sequence, stirred evenly, and then oxalic acid is added, wherein the mass ratio of phenol, formaldehyde, cardanol and oxalic acid is 1:1.2:1.0:0.05, the temperature is raised to 100° C. and refluxed for 5 hours, and dehydrated after the reaction to obtain a cardanol-modified phenolic resin; (2) mixing the cardanol-modified phenolic resin and epichlorohydrin uniformly, wherein the mass ratio of the cardanol-modified phenolic resin to epichlorohydrin is 1:1.3, reacting at 90° C. for 14 h, and then concentrating under reduced pressure and washing to obtain an epoxidized phenolic resin; (3) adding triallyl phosphate to N,N-dimethylformamide solvent, stirring to dissolve, and then continuing to add 3-(dimethylamino)-1-propanethiol and benzoin dimethyl ether initiator, wherein the mass ratio of triallyl phosphate, 3-(dimethylamino)-1-propanethiol, and benzoin dimethyl ether initiator is 1:1.6:0.02, and irradiating with 365nm ultraviolet light at 50°C for 4h. After the end, centrifuging, washing and drying are performed to obtain intermediate 1; (4) adding the intermediate 1 and sodium 3-chloro-2-hydroxypropanesulfonate to a reactor filled with N,N-dimethylformamide solvent, wherein the mass ratio of the intermediate 1 and sodium 3-chloro-2-hydroxypropanesulfonate is 1:2.2, introducing nitrogen protection, reacting at 80° C. for 10 h, and then removing the solvent by rotary evaporation and drying to obtain a hydroxylated phosphate; (5) adding epoxidized phenolic resin and hexamethylene diisocyanate into a reactor containing N,N-dimethylformamide solvent, stirring evenly, adding tetramethylammonium chloride catalyst, reacting at 90°C for 18 hours, and then adding hydroxylated phosphate, wherein the mass ratio of epoxidized phenolic resin, hexamethylene diisocyanate, tetramethylammonium chloride catalyst, and hydroxylated phosphate is 1.4:1:0.03:1.3, reacting at 110°C for 16 hours, and then distilling under reduced pressure, filtering and drying to obtain phosphorus-modified phenolic resin; (6) Adding 4-aminophenylboronic acid, phenol and formaldehyde to 1,4-dioxane solvent and stirring evenly, wherein the mass ratio of 4-aminophenylboronic acid, phenol and formaldehyde is 1:1.3:1.5, carrying out cyclization reaction, reflux reaction at 120° C. for 25 hours, and after the reaction, distilling under reduced pressure, washing and recrystallizing to obtain boric acid-containing benzoxazine; (7) 80 parts by weight of phenolic resin, 25 parts by weight of polycarbonate, 20 parts by weight of phosphorus-modified phenolic resin, 12 parts by weight of boric acid-containing benzoxazine, 2 parts by weight of silicone resin defoamer, 3 parts by weight of propylene glycol film-forming agent, and 14 parts by weight of water were added into a stirrer, and then stirred at 1000 r / min for 18 min to obtain a flame retardant coating. Example 3

[0016] (1) Phenol, formaldehyde and cardanol are added to a reactor in sequence, stirred evenly, and then oxalic acid is added, wherein the mass ratio of phenol, formaldehyde, cardanol and oxalic acid is 1:1.5:0.9:0.035, the temperature is raised to 90°C and refluxed for 4 hours, and dehydrated after the reaction to obtain a cardanol-modified phenolic resin; (2) mixing the cardanol-modified phenolic resin and epichlorohydrin uniformly, wherein the mass ratio of the cardanol-modified phenolic resin to epichlorohydrin is 1:1.2, reacting at 82° C. for 12 h, and then concentrating and washing under reduced pressure to obtain an epoxidized phenolic resin; (3) adding triallyl phosphate to N,N-dimethylformamide solvent, stirring to dissolve, and then continuing to add 3-(dimethylamino)-1-propanethiol and benzoin dimethyl ether initiator, wherein the mass ratio of triallyl phosphate, 3-(dimethylamino)-1-propanethiol, and benzoin dimethyl ether initiator is 1:1.4:0.015, and irradiating with 365nm ultraviolet light at 45°C for 3h. After the end, centrifuging, washing and drying are performed to obtain intermediate 1; (4) adding the intermediate 1 and sodium 3-chloro-2-hydroxypropanesulfonate to a reactor filled with N,N-dimethylformamide solvent, wherein the mass ratio of the intermediate 1 and sodium 3-chloro-2-hydroxypropanesulfonate is 1:1.8, introducing nitrogen protection, reacting at 65° C. for 8 h, and then removing the solvent by rotary evaporation and drying to obtain a hydroxylated phosphate; (5) adding epoxidized phenolic resin and hexamethylene diisocyanate into a reactor containing N,N-dimethylformamide solvent, stirring evenly, adding tetramethylammonium chloride catalyst, reacting at 75°C for 17 hours, and then adding hydroxylated phosphate, wherein the mass ratio of epoxidized phenolic resin, hexamethylene diisocyanate, tetramethylammonium chloride catalyst, and hydroxylated phosphate is 1.3:1:0.025:1.2, reacting at 100°C for 14 hours, and then distilling under reduced pressure, filtering and drying to obtain phosphorus-modified phenolic resin; (6) Adding 4-aminophenylboronic acid, phenol and formaldehyde to 1,4-dioxane solvent and stirring evenly, wherein the mass ratio of 4-aminophenylboronic acid, phenol and formaldehyde is 1:1.25:1.2, carrying out cyclization reaction, and reflux reaction at 110° C. for 22 hours. After the reaction, distilling under reduced pressure, washing and recrystallizing to obtain boric acid-containing benzoxazine; (7) 60 parts by weight of phenolic resin, 20 parts by weight of polycarbonate, 15 parts by weight of phosphorus-modified phenolic resin, 10 parts by weight of boric acid-containing benzoxazine, 1.5 parts by weight of silicone resin defoamer, 2.5 parts by weight of propylene glycol film-forming agent, and 10 parts by weight of water were added into a stirrer, and then stirred at 950 r / min for 17 min to obtain a flame retardant coating.

[0017] Comparative Example 1 Compared with Example 3, the comparative example is characterized in that no phosphorus-modified phenolic resin is added.

[0018] Comparative Example 2 Compared with Example 3, this comparative example is characterized in that no boric acid-containing benzoxazine is added.

[0019] Use an oxygen index meter to test the limiting oxygen index of the coating; use a horizontal and vertical combustion instrument to test the combustion level of the coating.

[0020] Table 1: Tests of flame retardancy.

[0021] project Limiting oxygen index (%) Combustion level Example 1 26 V-0 Example 2 34 V-0 Example 3 29 V-0 Comparative Example 1 23 V-1 Comparative Example 2 21 V-1

[0022] It can be seen from Table 1 that the flame retardant coatings prepared in Examples 1-3 of the present invention have better flame retardant effects than those prepared in Comparative Examples 1-2.

[0023] The flame retardant coatings obtained in Examples 1-3 and Comparative Examples 1-2 were subjected to fire resistance tests in accordance with GB14907-2018.

[0024] Table 2: Fire resistance test of flame retardant coatings containing phenolic resin.

[0025] project Fire resistance time (min) Example 1 125 Example 2 121 Example 3 113 Comparative Example 1 71 Comparative Example 2 70 It can be seen from Table 2 that compared with comparative examples 1-2, the fire retardant coatings of Examples 1-3 of the present invention have a longer fire retardant time, indicating that they have better fire retardant properties.

[0026] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A flame retardant coating, characterized in that: The invention comprises the following components by weight: 40-80 parts by weight of phenolic resin, 15-25 parts by weight of polycarbonate, 10-20 parts by weight of phosphorus-modified phenolic resin, 5-12 parts by weight of boric acid-containing benzoxazine, 1-2 parts by weight of silicone resin defoamer, 2-3 parts by weight of propylene glycol film-forming agent, and 8-14 parts by weight of water; The preparation method of the boric acid-containing benzoxazine comprises the following steps: S1. Add 4-aminophenylboronic acid, phenol and formaldehyde to 1,4-dioxane solvent, stir evenly, carry out cyclization reaction, reflux reaction at 90-120° C. for 18-25 hours, and after the reaction, perform vacuum distillation, wash and recrystallize to obtain boric acid-containing benzoxazine.

2. The flame retardant coating according to claim 1, characterized in that: The preparation method of the phosphorus-modified phenolic resin is as follows: (1) Phenol, formaldehyde and cardanol are added to the reactor in sequence, stirred evenly, and then oxalic acid is added, the temperature is raised to 80-100°C and refluxed for reaction for 3-5 hours, and dehydrated after the reaction to obtain cardanol-modified phenolic resin; (2) mixing the cardanol-modified phenolic resin and epichlorohydrin uniformly, wherein the mass ratio of the cardanol-modified phenolic resin to epichlorohydrin is 1:1.1-1.3, reacting at 75-90° C. for 8-14 hours, and then concentrating under reduced pressure and washing to obtain an epoxidized phenolic resin; (3) adding triallyl phosphate to N,N-dimethylformamide solvent, stirring to dissolve, and then adding 3-(dimethylamino)-1-propanethiol and benzoin dimethyl ether initiator, irradiating with 365 nm ultraviolet light at 40-50 °C for 2-4 h, centrifuging, washing and drying to obtain intermediate 1; (4) adding the intermediate 1, sodium 3-chloro-2-hydroxypropanesulfonate to a reactor filled with N,N-dimethylformamide solvent, introducing nitrogen protection, reacting at 50-80°C for 6-10 hours, and then removing the solvent by rotary evaporation and drying to obtain a hydroxylated phosphate; (5) Add the epoxidized phenolic resin and hexamethylene diisocyanate into a reactor containing N,N-dimethylformamide solvent, stir evenly, continue to add tetramethylammonium chloride catalyst, react at 60-90°C for 15-18h, then add hydroxylated phosphate, react at 90-110°C for 12-16h, and then distill under reduced pressure, filter and dry to obtain phosphorus-modified phenolic resin.

3. The flame retardant coating according to claim 2, characterized in that: The mass ratio of phenol, formaldehyde, cardanol and oxalic acid in (1) is 1:1.1-1.2:0.8-1.0:0.02-0.

05.

4. The flame retardant coating according to claim 2, characterized in that: The mass ratio of triallyl phosphate, 3-(dimethylamino)-1-propanethiol and benzoin dimethyl ether initiator in (3) is 1:1.2-1.6:0.01-0.

02.

5. The flame retardant coating according to claim 2, characterized in that: The mass ratio of the intermediate 1 and sodium 3-chloro-2-hydroxypropanesulfonate in (4) is 1:1.5-2.

2.

6. The flame retardant coating according to claim 2, characterized in that: The mass ratio of the epoxidized phenolic resin, hexamethylene diisocyanate, tetramethylammonium chloride catalyst and hydroxylated phosphate in (5) is 1.2-1.4:1:0.02-0.03:1.1-1.

3.

7. The flame retardant coating according to claim 1, characterized in that: The mass ratio of 4-aminophenylboronic acid, phenol and formaldehyde in S1 is 1:1.2-1.3:0.8-1.

5.

8. A method for preparing a flame retardant coating according to any one of claims 1 to 7, characterized in that: The preparation method of the flame retardant coating comprises the following steps: adding phenolic resin, polycarbonate, phosphorus-modified phenolic resin, boric acid-containing benzoxazine, silicone resin defoamer, propylene glycol film-forming agent and water into a stirrer, and then stirring at 900-1000 r / min for 15-18 minutes to obtain the flame retardant coating.