GB2599976A

GB2599976A - Reactive flame retardant containing phosphoryl benzimidazole and preparation method

Info

Publication number: GB2599976A
Application number: GB2105885.4A
Authority: GB
Inventors: Zhong Steve; Lan Jiashui; Zhu Weiming; Shi Yongyou; Zhang Zhixin
Original assignee: XIAMEN WAEXIM RUBBER CO Ltd
Current assignee: XIAMEN WAEXIM RUBBER CO Ltd
Priority date: 2020-10-13
Filing date: 2021-04-26
Publication date: 2022-04-20
Anticipated expiration: 2041-04-26
Also published as: GB202105885D0; CN112250903A; CN112250903B; GB2599976B

Abstract

A reactive flame retardant containing phosphoryl benzimidazole, with a general formula: is prepared by the reaction of 2-aminobenzimidazole and phosphoryl dichloride in a one-step process. The reactive flame retardant containing phosphoryl benzimidazole provided in this disclosure can be widely used in epoxy resins in the fields of electronic, building materials, and has broad application prospects.

Description

DESCRIPTION

Reactive Flame Retardant Containing Phosphoryl Benzimidazole and Preparation Method thereof

TECHICAL FIELD

[0001] The disclosure relates to the technical field of flame retardants, especially to a reactive flame retardant containing phosphoryl benzimidazole and preparation method.

BACKGROUND

[0002] Epoxy resin is one of the most extensively used thermosetting resins for various industrial fields such as surface coatings, composite materials, semiconductor packaging, electronics, etc. However, the epoxy resin is very flammable that restricts its application in many fields including electronics and chemistry and chemical engineering. Accordingly, the development of flame-retardant epoxy resins is of great significance for broadening the application and development of epoxy resins.

[0003] In present, halogen-containing flame retardants have been widely used for epoxy resins because of their excellent flame retardancy and being outstanding cost-effective. However, in consideration of environmental and security issues, the application of halogen-containing flame retardants is restricted. Phosphorus-containing or nitrogen-containing flame retardants have become one of the important substitutes for halogen flame retardants because of their non-toxicity and high flame retardancy. Phosphorus-containing flame retardants can inhibit combustion by capturing free radicals and promoting the formation of carbon layers. Nitrogen-containing flame retardants can generate non-inflammable gases during the combustion process. Therefore, a design to synthesize flame retardants containing both phosphorus and nitrogen at the same time may give epoxy resin excellent flame retardant properties through the synergistic effect of phosphorus and nitrogen. For example, the flame retardant performance of epoxy resin modified with ammonium polyphosphate has been improved to a certain extent. However, the addition of flame retardants reduces the heat resistance of the epoxy resins (Zong-Min Zhu, etc. "Influence of a novel P/N-containing oligomer on flame retardancy and thermal degradation of intumescent flame-retardant epoxy resin," Polymer Degradation and Stability, 2019, 162, 129-137). Therefore, it is of great significance in research and practice to develop a new flame retardant with both flame retardancy and heat resistance.

SUMMARY OF THIS INVENTION

[0004] The object of the present disclosure is to provide a reactive flame retardant containing phosphoryl benzimidazole and a preparation method thereof.

[0005] The reactive flame retardant containing phosphoryl benzimidazole is specified herein. The general formula of the flame retardant is as follows: where, [0006] The preparation method for the reactive flame retardant containing phosphoryl benzimidazole comprises the following steps: step 1, adding 2-aminobenzimidazole, organic solvent and triethylamine to a three-necked flask successively under the protection of inert gas; after stirring to dissolve, adding a mixture of phosphoryl dichloride and organic solvent dropwise to a flask through a constant pressure dropping funnel; after the dropwisc addition is completed, keeping the flask at a temperature for a time for reaction; step 2, cooling, filtering, washing and drying the solution obtained by the reaction to obtain the reactive flame retardant containing phosphoryl benzimidazole, the reaction equation thereof is specified as follows: 0..------iy-N u, u..,,,,ix *--,.." Cl.P Cl -, 14 N t ;I ;------- *-...,-,--)-- n ----- --' n ---,..---H 14 where, [0007] In step 1, the molar ratio of phosphor0 dichloride to 2-aminobenzimidazole is 1: (2-3). [0008] In step 1, the molar ratio of 2-aininobenzimidazole to triethylamine is 1:(1-1.5).

[0009] In step 1, the temperature for the reaction is 60°C-70°C, and the time for the reaction is 4h-8h.

[0010] In step 1, the organic solvent is one or more mixtures selected from the group consisting of tetrahydrofuran, dithloroethane and chloroform.

[0011] The advantages of the present disclosure is specified as follows.

[0012] I. The present disclosure uses "one-step method" synthesis, which has simple preparation process, controllable reaction conditions, and is easy for large-scale production. Flame retardant elements, including P (phosphorus) and N (nitrogen), and benzimidazole are introduced into the structure of the reactive flame retardant, and therefore improving the flame retardancy and heat resistance of epoxy resins.

[0013] 2. The general formula of the flame retardant in the present disclosure contains reactive groups such as secondary amines and tertiary amines which may participate in the curing reaction of the epoxy resin to improve the compatibility of the flame retardant and the matrix, thereby enhancing mechanical properties of the prepared flame-retardant epoxy resin.

DETAILED DESCRIPTION OF THE DISCLOSURE

[0014] The present disclosure will be further specified below. However, the protection scope of the present disclosure shall not be limited to this context.

[0015] For the sake of clarity, not all the features of the actual embodiments are described. In the following description, well-known fiinctions and structures are not described in detail, because they may confuse the present disclosure due to unnecessary details, but they should be considered that it is necessary to make a lot of implementation details to achieve the developer's specific goals, such as modifying from one embodiment to another in accordance with the relevant system or business restrictions, during the development of any actual embodiments. Additionally, it should be considered that such development work may be complicated and time-consuming, but it is just routine work for those skilled in the art.

[0016] Embodiment 1 [0017] Under the protection of inert gas. 40 mmol 2-aminobenzimidazole, 60 mL tetrahydrofuran and 40 mmol triethvlamine are added to a three-necked flask in sequence. After fully stirring to dissolve, a mixture of 20 mmol phenylphosphoryl dichloride and 30 mL tetrahydrofuran is slowly dripped into the three-necked flask. After the dropwise addition is completed, the flask is kept at a temperature of 60°C for 8 hours for reaction. After the reaction is completed, the solution obtained bythe reaction is cooled, filtered, washed, and dried to obtain the reactive flame retardant containing phosphoryl benzimidazole. The flame retardant has the following general formula: Krk-kz+---N H ? H \k> ht e

H

[0018] FT1R: P= 0(1282, 1170cm-1), P-N(962cm-1), C= N(1577cm-1), C-N(1463cm-1), N0(1644cm-1), Ph(1643cm-1), P-C (1438cm-1) [0019] Embodiment 2 [0020] Under the protection of inert gas, 60 mmol 2-aminobenzimidazole, 80 mL tetrahydrofuran and 90 mmol triethylamine are added to a three-necked flask in sequence After fully stirring to dissolve, a mixture of 20 mmol phenylphosphoryl dichloride and 50 nil_. tetrahydrofuran is slowly dripped into the three-necked flask. After the dropwise addition is completed, the flask is kept at a temperature of 70°C for 4 hours for reaction After the reaction is completed, the solution obtained bythe reaction is cooled, filtered, washed, and dried to obtain the reactive flame retardant containing phosphoryl benzimidazolc. The flame retardant has the following general formula:

H II Fi H

[0021] FT1R: P=0(1280. 1172cm-1). P-N(965cm-1), C=N(1573cm-1), C-N(1460cm-1), NH(1622cm-1), Ph(1601cm-1), P-C(1439cm-1) [0022] Embodiment 3 [0023] Under the protection of inert gas, 40 mmol 2-aminobenzimidazole, 60 mL tetrahydrofuran and 40 mmol triethylamine are added to a three-necked flask in sequence. After fully stirring to dissolve, a mixture of 20 mmol phenylphosphoryl dichloride and 30 mL tetrahydrofuran is slowly dripped into the three-necked flask. After the dropwise addition is completed, the flask is kept at a temperature of 60°C for 8 hours for reaction. After the reaction is completed, the solution obtained bythe reaction is cooled, filtered, washed, and dried to obtain the reactive flame retardant containing phosphoryl benzimidazole. The flame retardant has the following general formula: H 4?-11 13/41

--N \

N-

[0024] FT1R: P=0(1280, 1162cm-1), P-N(960cm-1), C=N(1570cm-1), C-N(1460cm-1), NH(1642cm-1), Ph(1603cm-1), P-O-C(1180, 960cm-1).

[0025] Embodiment 4 [0026] Under the protection of inert gas, 60 mmol 2-aminobenzimidazole, 80 mL tetrahydrofuran and 90 mmol triethylamine are added to a three-necked flask in sequence. After fully stirring to dissolve, a mixture of 20 mmol phenylphosphoryl dichloride and 50 mL tetrahydrofuran is slowly dripped into the three-necked flask. After the dropwise addition is completed, the flask is kept at a temperature of 70°C for 4 hours for reaction. After the reaction is completed, the solution obtained bythe reaction is cooled, filtered, washed, and dried to obtain the reactive flame retardant containing phosphoryl benzimidazole. The flame retardant has the following general fonla:

H H

N P N

I -N 0

[0027] FUR: P=0(1281, 1160cm-1), P-N(961cm-1), C=N(1571cm-1), C-N(1462cm-1), NH(1640cm-1), Ph(1597cm-1), P-O-C(1181, 962cm-1).

[0028] Although the present disclosure has been described and enumerated in detail, it should be understood that for those skilled in the art, it is obvious for those skilled in the art to modify the above-mentioned embodiments or adopt equivalent alternatives. Those modifications or improvements made without departing from the spirit of the present disclosure shall be considered to fall within the scope of the present disclosure.

Claims

WHAT IS CLAIMED IS: 1. A reactive flame retardant containing phosphoryl benzimidazole characterized in that the general formula of the flame retardant is as follows: where, 2. A preparation method for a reactive flame retardant containing phosphoryl benzimidazole, charactcrizcd in that the preparation method comprises the following steps: step 1, adding 2-aminoberizimidazole, organic solvent and triethylamine to a three-necked flask successively under the protection of inert gas; after stirring to dissolve, adding a mixture of phosphoryl dichloride and organic solvent dropwise to a flask through a constant pressure dropping funnel; after the dropwise addition is completed, keeping the flask at a temperature for a time for reaction; step 2, cooling, filtering, washing and drying the solution obtained by the reaction to obtain the reactive flame retardant containing phosphoryl benzimidazole.
3. The preparation method according to claim 2, characterized in that in step 1, the molar ratio of phosphoryl dichloride to 2-aminobenzimidazole is 1: (2-3).
4. The preparation method according to claim 2, characterized in that in step 1, the molar ratio of 2 -aminobenzimidazole to triethylamine is 1:0-1.5).
5. The preparation method according to claim 2, characterized in that in step I, the temperature for the reaction is 60°C-70°C. and the time for the reaction is 4h-8h.
6. The preparation method according to claim 2, characterized in that in step 1, the organic solvent is one or more mixtures selected from the group consisting of tetrahydrofuran, dichloroethanc and chloroform.