A halogen-free low-smoke composite flame retardant and preparation method thereof

Abstract

The present invention discloses a halogen-free low-smoke composite flame retardant and a preparation method thereof, and belongs to the technical field of flame retardants. The halogen-free low-smoke composite flame retardant of the present invention is prepared by Michael addition reaction, nucleophilic substitution reaction and esterification reaction, and the composite flame retardant of the present invention contains rich halogen-free flame retardant elements such as nitrogen, phosphorus, silicon and multiple long carbon chains. The composite flame retardant of the present invention contains lipophilic ester groups, benzene rings and long carbon chains, and has good compatibility with polymer resins, and the flame retardant has silaneoxy groups grafted on inorganic materials such as fillers. Therefore, the flame retardant of the present invention can exert efficient, safe and long-lasting and stable flame retardant and smoke suppression effects through the synergistic effect of nitrogen, phosphorus and silicon halogen-free flame retardant elements, and can also improve the mechanical properties of the material.

Description

Technical Field

[0001] The invention belongs to the technical field of flame retardants, and in particular relates to a halogen-free and low-smoke composite flame retardant and a preparation method thereof. Background Art

[0002] Flame retardants are mainly divided into two categories according to the way polymers obtain flame retardant properties, one is additive flame retardants and the other is reactive flame retardants. Additive flame retardants are mainly compounded with polymer materials by physical methods, which improves the flame retardant properties of polymers without affecting the properties of the materials, so that they can be applied to related fields. Due to the characteristics of easy preparation, low cost and simple processing of additive flame retardants with polymers, it has become the most economical and rapid method to improve the flame retardancy of materials and is widely used in the field of flame retardant polymers. Reactive flame retardants mainly refer to polymers that are designed and prepared to be flame retardant themselves, or flame retardants are grafted into polymer chains through copolymerization or grafting modification to make polymers have flame retardant properties.

[0003] The use of flame retardants has effectively reduced the combustion performance of polymers in many aspects, effectively reducing the occurrence of fires. However, most traditional flame retardants contain halogens, and when thermally decomposed, they mostly release a large amount of smoke and halogen-containing toxic gases, which greatly limits their application. Therefore, it is particularly necessary to synthesize and prepare new halogen-free and low-smoke flame retardants using new principles and methods. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects of the prior art and provide a halogen-free low-smoke composite flame retardant and a preparation method thereof.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A method for preparing a halogen-free low-smoke composite flame retardant comprises the following steps:

[0007] S1. Blow nitrogen gas into a dry brown three-necked flask for 30 minutes to drive away the air in the flask, then add piperazine, hydroxyethyl methacrylate, DBU (1,8-diazobispiro[5.4.0]undec-7-ene) and acetonitrile, stir evenly and place in an oil bath for stirring and reaction for 1 hour. After the reaction is completed, wash the reaction product with saturated brine for 3 times, take the organic phase, dry it with anhydrous sodium sulfate, filter it, and distill the filtrate under reduced pressure to obtain intermediate 1; the amount ratio of piperazine, hydroxyethyl methacrylate, DBU and acetonitrile is 5.1g:6.7mL:1.9mL:100mL;

[0008] Under the catalytic action of DBU, the molar ratio of piperazine to hydroxyethyl methacrylate is controlled to be 1.05-1.1:1, and piperazine and hydroxyethyl methacrylate undergo Michael addition reaction. The reaction process is as follows:

[0009]

[0010] S2. Blow nitrogen gas into a dry three-necked flask for 30 minutes to drive away the air in the flask, then add 1,3-bis(chloromethyl)-1,1,3,3-tetramethyldisiloxane, triethylamine and DMSO (dimethyl sulfoxide), stir and dissolve, slowly add a mixed solution of intermediate 1 and DMSO, heat and react for 3 hours, cool to room temperature after the reaction, and distill under reduced pressure to obtain intermediate 2; the amount ratio of intermediate 1, 1,3-bis(chloromethyl)-1,1,3,3-tetramethyldisiloxane, triethylamine and DMSO is 10.4 g:11.3 mL:10 mL:120 mL;

[0011] Under the action of triethylamine, the molar ratio of intermediate 1 to 1,3-bis(chloromethyl)-1,1,3,3-tetramethyldisiloxane is controlled to be 1:1.05-1.1, and the -NH- of intermediate 1 and a -Cl of 1,3-bis(chloromethyl)-1,1,3,3-tetramethyldisiloxane undergo nucleophilic substitution reaction. The reaction process is as follows:

[0012]

[0013] S3, nitrogen was blown into a dry three-necked flask for 30 minutes to drive away the air in the flask, and then intermediate 2, octadecylamine, pyridine and DMSO were added, stirred and dissolved, and then heated to react for 3 hours. After the reaction was completed, it was cooled to room temperature and distilled under reduced pressure to obtain intermediate 3; the amount ratio of intermediate 2, octadecylamine, pyridine and DMSO was 9.5g:6.7g:2.8mL:160mL;

[0014] Under the condition that pyridine is used as an acid-binding agent, the molar ratio of intermediate 2 to octadecylamine is controlled to be 1:1.05-1.1, and the -Cl of intermediate 2 and the -NH2 of octadecylamine undergo a nucleophilic substitution reaction. The reaction process is as follows:

[0015]

[0016] S4, nitrogen was blown into a dry three-necked flask for 30 minutes to drive away the air in the flask, and then intermediate 3, triethylamine and DMF (N,N-dimethylformamide) were added, and after stirring and dissolving, 3-chloropropyltrimethoxysilane was slowly added, and the temperature was raised to react for 3 hours. After the reaction was completed, it was cooled to room temperature and distilled under reduced pressure to obtain intermediate 4; the amount ratio of intermediate 3, 3-chloropropyltrimethoxysilane, triethylamine and DMF was 12.9 g:3.7 mL:2.9 mL:130 mL;

[0017] Under the action of triethylamine, -NH- of intermediate 3 and -Cl of 3-chloropropyltrimethoxysilane undergo nucleophilic substitution reaction. The reaction process is as follows:

[0018]

[0019] S5. Blow nitrogen through a dry three-necked flask for 30 minutes to drive away the air in the flask, then add phenylphosphonic acid dichloride, triethylamine and DMF, cool to 15°C with ice brine, slowly add intermediate 4 while stirring, keep the temperature at 15°C with ice brine, and keep the reaction for 1.5 hours. After the reaction, perform vacuum distillation and column chromatography purification at 50°C and 4-4.7kPa (mixed solvent of eluent benzene and ethyl acetate, volume ratio of benzene and ethyl acetate is 8:2), and vacuum distillation to obtain a halogen-free and low-smoke composite flame retardant. The dosage ratio of phenylphosphonic acid dichloride, intermediate 4, triethylamine and DMF is 3.0g:25.3g:6.4mL:180mL.

[0020] Under the action of triethylamine, the molar ratio of phenylphosphonyl dichloride and intermediate 4 is controlled to be 1:2 and intermediate 4 is slightly excessive, and phenylphosphonyl dichloride and intermediate 4 can undergo esterification reaction. The reaction process is as follows:

[0021]

[0022] The phosphorus element in the composite flame retardant provides an acid source, which can react with the polymer resin to promote the formation of carbonized products; the nitrogen element provides a gas source to expand and foam the system, and at the same time promotes the formation of a carbonized layer to form porous foamed carbon; the silicon element generates an inorganic heat-insulating and insulating protective layer containing -Si-O bonds and -Si-C- bonds during combustion, which not only prevents the decomposition products generated by combustion from escaping, but also inhibits the thermal decomposition of the polymer material, achieving the purpose of high flame retardancy, low smoke emission, and low harmfulness. The composite flame retardant of the present invention exerts an efficient and safe flame retardant effect and smoke suppression effect through the synergistic effect of nitrogen, phosphorus, and silicon halogen-free flame retardant elements.

[0023] The composite flame retardant contains a plurality of long carbon chains, and the methylene long chains that can rotate and stretch freely can enhance toughness and impact strength; the lipophilic ester group, benzene ring and long carbon chain in the composite flame retardant make the composite flame retardant have good compatibility with the polymer resin; the composite flame retardant contains a plurality of silaneoxy groups, which can form chemical bonds with inorganic materials such as fillers, so that the flame retardant of the present invention can be applied to certain polymer materials to increase the dispersion of the filler, and at the same time can also improve its own dispersion uniformity, so that the flame retardant can fully and stably exert the flame retardant effect and improve the mechanical properties of the material.

[0024] Furthermore, in step S1, the temperature of the oil bath is 30-40°C.

[0025] Furthermore, in step S1, the temperature of the oil bath is 30°C.

[0026] Furthermore, the reaction temperature in step S2 is 65-90°C.

[0027] Furthermore, the reaction temperature in step S2 is 75°C.

[0028] Furthermore, the reaction temperature in step S3 is 70-90°C.

[0029] Furthermore, the reaction temperature in step S3 is 80°C.

[0030] Furthermore, the reaction temperature in step S4 is 80-100°C.

[0031] Furthermore, the reaction temperature in step S4 is 90°C.

[0032] The invention also discloses a halogen-free and low-smoke composite flame retardant, which is prepared according to the preparation method of the halogen-free and low-smoke composite flame retardant.

[0033] Beneficial effects of the present invention: The composite flame retardant of the present invention contains lipophilic ester groups, benzene rings and long carbon chains, has good compatibility with polymer resins, and the flame retardant has silaneoxy groups grafted on inorganic materials such as fillers. Therefore, the flame retardant of the present invention can exert efficient, safe and long-lasting and stable flame retardant and smoke suppression effects through the synergistic effect of nitrogen, phosphorus and silicon halogen-free flame retardant elements, while also improving the mechanical properties of the material. DETAILED DESCRIPTION

[0034] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] Example 1

[0036] The flame retardant is prepared in the following steps:

[0037] S1, nitrogen was blown into a dry 250mL brown three-necked flask for 30min to drive away the air in the flask, and then 5.1g piperazine, 6.7mL hydroxyethyl methacrylate, 1.9mL DBU and 100mL acetonitrile were added, stirred evenly and placed in a 30°C oil bath for stirring and reaction for 1h. After the reaction was completed, the reaction product was washed 3 times with saturated brine, and the organic phase was dried with anhydrous sodium sulfate, filtered, and the filtrate was distilled under reduced pressure to obtain intermediate 1;

[0038] S2, nitrogen was blown into a dry 250 mL three-necked flask for 30 min to drive away the air in the flask, then 11.3 mL 1,3-bis(chloromethyl)-1,1,3,3-tetramethyldisiloxane, 10 mL triethylamine and 20 mL DMSO were added, and after stirring and dissolving, a mixed solution of 10.4 g intermediate 1 and 100 mL DMSO was slowly added, and the temperature was raised to 75 ° C for 3 h. After the reaction was completed, it was cooled to room temperature and distilled under reduced pressure to obtain intermediate 2;

[0039] S3, nitrogen was blown into a dry 500 mL three-necked flask for 30 min to drive away the air in the flask, and then 9.5 g of intermediate 2, 6.7 g of octadecylamine, 2.8 mL of pyridine and 160 mL of DMSO were added, stirred to dissolve, and then heated to 80 ° C for 4 h. After the reaction was completed, it was cooled to room temperature and distilled under reduced pressure to obtain intermediate 3;

[0040] S4, nitrogen was blown into a dry 250 mL three-necked flask for 30 min to drive away the air in the flask, then 12.9 g of intermediate 3, 2.9 mL of triethylamine and 130 mL of DMF were added, and after stirring and dissolving, 3.7 mL of 3-chloropropyltrimethoxysilane was slowly added, and the temperature was raised to 90 ° C for 4 h. After the reaction was completed, it was cooled to room temperature and distilled under reduced pressure to obtain intermediate 4;

[0041] S5. Blow nitrogen gas into a dry 500mL three-necked flask for 30 minutes to drive away the air in the flask, then add 3.0g of phenylphosphonic dichloride, 6.4mL of triethylamine and 180mL of DMF, cool to 15°C with ice brine, slowly add 25.3g of intermediate 4 while stirring, and keep the temperature at 15°C with ice brine. Keep the reaction for 1.5 hours. After the reaction is completed, perform vacuum distillation at 50°C and 4-4.7kPa, column chromatography purification (the eluent is a mixed solvent of benzene and ethyl acetate, and the volume ratio of benzene to ethyl acetate is 8:2), and vacuum distillation to obtain a halogen-free and low-smoke composite flame retardant.

[0042] Example 2

[0043] The flame retardant is prepared in the following steps:

[0044] S1, nitrogen was blown into a dry 250mL three-necked flask for 30 minutes to drive away the air in the flask, and then 5.1g piperazine, 6.7mL hydroxyethyl methacrylate, 1.9mL DBU and 100mL acetonitrile were added, stirred evenly and placed in a 40°C oil bath for stirring and reaction for 1h. After the reaction was completed, the reaction product was washed 3 times with saturated brine, and the organic phase was dried over anhydrous sodium sulfate, filtered, and the filtrate was distilled under reduced pressure to obtain intermediate 1;

[0045] S2, nitrogen was blown into a dry 250 mL three-necked flask for 30 min to drive away the air in the flask, then 11.3 mL 1,3-bis(chloromethyl)-1,1,3,3-tetramethyldisiloxane, 10 mL triethylamine and 20 mL DMSO were added, and after stirring and dissolving, a mixed solution of 10.4 g intermediate 1 and 100 mL DMSO was slowly added, and the temperature was raised to 90 ° C for reaction for 3 h. After the reaction was completed, it was cooled to room temperature and distilled under reduced pressure to obtain intermediate 2;

[0046] S3, nitrogen was blown into a dry 500 mL three-necked flask for 30 min to drive away the air in the flask, and then 9.5 g of intermediate 2, 6.7 g of octadecylamine, 2.8 mL of pyridine and 160 mL of DMSO were added, and the mixture was stirred and dissolved, and then heated to 90 °C for 4 h. After the reaction was completed, the mixture was cooled to room temperature and distilled under reduced pressure to obtain intermediate 3;

[0047] S4, nitrogen was blown into a dry 250 mL three-necked flask for 30 min to drive away the air in the flask, then 12.9 g of intermediate 3, 2.9 mL of triethylamine and 130 mL of DMF were added, and after stirring and dissolving, 3.7 mL of 3-chloropropyltrimethoxysilane was slowly added, and the temperature was raised to 100 ° C for 4 h. After the reaction was completed, it was cooled to room temperature and distilled under reduced pressure to obtain intermediate 4;

[0048] S5. Blow nitrogen gas into a dry 500mL three-necked flask for 30 minutes to drive away the air in the flask, then add 3.0g of phenylphosphonic dichloride, 6.4mL of triethylamine and 180mL of DMF, cool to 15°C with ice brine, slowly add 25.3g of intermediate 4 while stirring, and keep the temperature at 15°C with ice brine. Keep the reaction for 1.5 hours. After the reaction is completed, perform vacuum distillation at 50°C and 4-4.7kPa, column chromatography purification (the eluent is a mixed solvent of benzene and ethyl acetate, and the volume ratio of benzene to ethyl acetate is 8:2), and vacuum distillation to obtain a halogen-free and low-smoke composite flame retardant.

[0049] Example 3

[0050] The flame retardant is prepared in the following steps:

[0051] S1, nitrogen was blown into a dry 250mL three-necked flask for 30 minutes to drive away the air in the flask, and then 5.1g piperazine, 6.7mL hydroxyethyl methacrylate, 1.9mL DBU and 100mL acetonitrile were added, stirred evenly and placed in a 35°C oil bath for stirring and reaction for 1h. After the reaction was completed, the reaction product was washed 3 times with saturated brine, and the organic phase was dried over anhydrous sodium sulfate, filtered, and the filtrate was distilled under reduced pressure to obtain intermediate 1;

[0052] S2, nitrogen was blown into a dry 250mL three-necked flask for 30 minutes to drive away the air in the flask, and then 11.3mL 1,3-bis(chloromethyl)-1,1,3,3-tetramethyldisiloxane, 10mL triethylamine and 20mL DMSO were added, and after stirring and dissolving, a mixed solution of 10.4g intermediate 1 and 100mL DMSO was slowly added, and the temperature was raised to 65°C for reaction for 3h. After the reaction was completed, it was cooled to room temperature and distilled under reduced pressure to obtain intermediate 2;

[0053] S3, nitrogen was blown into a dry 500 mL three-necked flask for 30 min to drive away the air in the flask, and then 9.5 g of intermediate 2, 6.7 g of octadecylamine, 2.8 mL of pyridine and 160 mL of DMSO were added, stirred to dissolve, and then heated to 70 ° C for 3 h. After the reaction was completed, it was cooled to room temperature and distilled under reduced pressure to obtain intermediate 3;

[0054] S4, nitrogen was blown into a dry 250 mL three-necked flask for 30 min to drive away the air in the flask, then 12.9 g of intermediate 3, 2.9 mL of triethylamine and 130 mL of DMF were added, and after stirring and dissolving, 3.7 mL of 3-chloropropyltrimethoxysilane was slowly added, and the temperature was raised to 80 ° C for 3 h. After the reaction was completed, it was cooled to room temperature and distilled under reduced pressure to obtain intermediate 4;

[0055] S5. Blow nitrogen gas into a dry 500mL three-necked flask for 30 minutes to drive away the air in the flask, then add 3.0g of phenylphosphonic dichloride, 6.4mL of triethylamine and 180mL of DMF, cool to 15°C with ice brine, slowly add 25.3g of intermediate 4 while stirring, and keep the temperature at 15°C with ice brine. Keep the reaction for 1.5 hours. After the reaction is completed, perform vacuum distillation at 50°C and 4-4.7kPa, column chromatography purification (the eluent is a mixed solvent of benzene and ethyl acetate, and the volume ratio of benzene to ethyl acetate is 8:2), and vacuum distillation to obtain a halogen-free and low-smoke composite flame retardant.

[0056] Comparative Example 1

[0057] The remaining steps remain unchanged, only step S5 of Example 1 is removed to prepare the composite flame retardant.

[0058] Comparative Example 2

[0059] The remaining steps remain unchanged, only step S4 and step S5 of Example 1 are removed to prepare a composite flame retardant.

[0060] Comparative Example 3

[0061] Prepare flame retardant Doher992 of equal quality from Dongguan Doher New Material Technology Co., Ltd.

[0062] Performance Testing

[0063] Table 1 below shows the flame retardant properties of the flame retardants obtained in Examples 1-3 and Comparative Examples 1-3:

[0064] Table 1

[0065] Test items Limiting oxygen index % Test items Limiting oxygen index % Example 1 39.9 Comparative Example 1 37.5 Example 2 39.7 Comparative Example 2 36.4 Example 3 39.8 Comparative Example 3 34.7

[0066] It can be seen from the test results in Table 1 that the composite flame retardants prepared in Examples 1-3 of the present invention have a more excellent flame retardant effect.

[0067] A silicone rubber material comprises, by mass, 100 parts of silicone rubber, 20 parts of white carbon black, 3 parts of hydroxy silicone oil, 2 parts of dipentadienyl vulcanizer, and 8 parts of flame retardant; wherein the flame retardant is respectively taken from the flame retardants prepared in Examples 1-3 and Comparative Examples 1-3.

[0068] The obtained silicone rubber was made into samples according to the relevant standard requirements and then subjected to performance tests. The test results are shown in Table 2 below:

[0069] Table 2

[0070]

[0071] In the description of the specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0072] The above contents are merely examples and explanations of the present invention. Those skilled in the art 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 invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

Claims

1. A method for preparing a halogen-free low-smoke composite flame retardant, characterized in that: The steps include: S1. After nitrogen is blown into the flask, piperazine, hydroxyethyl methacrylate, DBU and acetonitrile are added, stirred and reacted for 1 hour, washed, dried, filtered, and distilled under reduced pressure to obtain intermediate 1. The structural formula of intermediate 1 is as follows: S2. After nitrogen is blown into the flask, 1,3-bis(chloromethyl)-1,1,3,3-tetramethyldisiloxane, triethylamine and DMSO are added, and after stirring, intermediate 1 and DMSO are added. After reacting for 3 hours, the reaction is carried out by vacuum distillation to obtain intermediate 2. The structural formula of intermediate 2 is as follows: S3, after nitrogen blowing the flask, add intermediate 2, octadecylamine, pyridine and DMSO, stir and react for 3 hours, and distill under reduced pressure to obtain intermediate 3. The structural formula of intermediate 3 is as follows: S4, after nitrogen blowing the flask, add intermediate 3, triethylamine and DMF, stir and add 3-chloropropyltrimethoxysilane, react for 3h, and distill under reduced pressure to obtain intermediate 4. The structural formula of intermediate 4 is as follows: S5. After nitrogen is blown into the flask, phenylphosphonic acid dichloride, triethylamine and DMF are added, cooled to 15°C, stirred and then intermediate 4 is added. The mixture is reacted at 15°C for 1.5 hours, and vacuum distilled and purified by column chromatography. Vacuum distilled to obtain a halogen-free and low-smoke composite flame retardant. The structural formula of the composite flame retardant is as follows:

2. The method for preparing a halogen-free low-smoke composite flame retardant according to claim 1, characterized in that: The usage ratio of piperazine, hydroxyethyl methacrylate, DBU and acetonitrile in step S1 is 5.1 g:6.7 mL:1.9 mL:100 mL.

3. The method for preparing a halogen-free low-smoke composite flame retardant according to claim 1, characterized in that: The usage ratio of the intermediate 1, 1,3-bis(chloromethyl)-1,1,3,3-tetramethyldisiloxane, triethylamine and DMSO in step S2 is 10.4 g:11.3 mL:10 mL:120 mL.

4. The method for preparing a halogen-free low-smoke composite flame retardant according to claim 1, characterized in that: The usage ratio of intermediate 2, octadecylamine, pyridine and DMSO in step S3 is 9.5 g:6.7 g:2.8 mL:160 mL.

5. The method for preparing a halogen-free low-smoke composite flame retardant according to claim 1, characterized in that: The usage ratio of intermediate 3, 3-chloropropyltrimethoxysilane, triethylamine and DMF in step S4 is 12.9 g:3.7 mL:2.9 mL:130 mL.

6. The method for preparing a halogen-free low-smoke composite flame retardant according to claim 1, characterized in that: The usage ratio of phenylphosphonic acid dichloride, intermediate 4, triethylamine and DMF in step S5 is 3.0 g:25.3 g:6.4 mL:180 mL.

7. The method for preparing a halogen-free low-smoke composite flame retardant according to claim 1, characterized in that: The reaction temperature in step S1 is 30-40°C; the reaction temperature in step S2 is 65-90°C; the reaction temperature in step S3 is 70-90°C; and the reaction temperature in step S4 is 80-100°C.

8. The method for preparing a halogen-free low-smoke composite flame retardant according to claim 7, characterized in that: The reaction temperature in step S1 is 30°C; the reaction temperature in step S2 is 75°C; the reaction temperature in step S3 is 80°C; and the reaction temperature in step S4 is 90°C.

9. A halogen-free low-smoke composite flame retardant, characterized in that: The invention discloses a halogen-free low-smoke composite flame retardant prepared according to the preparation method of any one of claims 1 to 8.

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