Phosphorus-containing flame retardant curing agent, its preparation method and application

Abstract

The present invention provides a phosphorus-containing flame-retardant curing agent, its preparation method and application. The phosphorus-containing flame-retardant curing agent is obtained by a substitution reaction of an organophosphorus chloride and 2,4,6-tris(dimethylaminomethyl)phenol (DMP-30). In the present invention, a tertiary amine group with curing activity and a phosphorus-containing group with good flame-retardant effect are constructed in one molecule to obtain a class of epoxy curing agents with flame-retardant effect. They have good curing activity for epoxy resins, and the cured epoxy products have excellent flame-retardant properties and mechanical properties.

Description

Technical Field

[0001] The present invention belongs to the technical field of intrinsically flame - retardant epoxy resin materials, and particularly relates to a phosphorus - containing flame - retardant curing agent, its preparation method and application. Background Art

[0002] Epoxy resins have excellent comprehensive properties and are widely used in the fields of electronics industry, automobiles, rail transit, ships, aerospace, etc. However, epoxy resins are flammable materials, which limits their scope of application. Adding phosphorus - based flame retardants to the epoxy resin system is an effective method to improve the flame - retardant performance of epoxy resin materials. Phosphorus - based flame retardants refer to flame retardants containing phosphate groups, mainly including tributyl phosphate, diphenyl ether and antimony pentoxide. There are a large number of hydroxyl groups in the molecules of phosphorus - based flame retardants, which can react with halogen - containing materials to form unstable complexes, reducing the flammability of the materials; at the same time, due to the small hygroscopicity and low smoke generation of phosphorus, it has good water resistance and moisture resistance.

[0003] However, at present, most phosphorus - based flame retardants are additive type and do not participate in the curing reaction of epoxy resins. Although they can effectively improve the flame - retardant performance, they have a greater negative impact on other properties of the materials, such as thermal properties and mechanical properties. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a kind of phosphorus - containing flame - retardant curing agent, its preparation method and application aiming at the deficiencies of the above - mentioned existing technologies. It has good curing activity for epoxy resins, and the cured epoxy resin has excellent flame - retardant performance and mechanical properties.

[0005] The technical solution adopted by the present invention to solve the above - mentioned problems is as follows:

[0006] The present invention provides a phosphorus - containing flame - retardant curing agent, which is obtained by the substitution reaction of organophosphorus chloride and 2,4,6 - tris(dimethylaminomethyl)phenol (DMP - 30).

[0007] As a preferred embodiment of the above - mentioned scheme, the organophosphorus chloride is mainly selected from one of diphenylphosphinous chloride, diphenylphosphine chloride, diphenyl phosphorochloridate, 6 - chloro - 6H - dibenzo[c,e][1,2]oxaphosphinine - 6 - oxide, phenylphosphonic dichloride or phenoxyphosphoryl dichloride, etc.

[0008] The present invention also provides a preparation method of the phosphorus - containing flame - retardant curing agent, including the following steps:

[0009] Mix 2,4,6-tris(dimethylaminomethyl)phenol (DMP-30), an acid-binding agent, and a reaction solvent uniformly in a reaction kettle, and continuously introduce a protective gas. Then, dropwise add an organic solution of organophosphorus chloride to the reaction kettle under the conditions of 25-70°C, a protective gas, and stirring; after the dropwise addition of the organic solution containing organophosphorus chloride is completed, stir and react at 50-80°C for 2-8 h; after the reaction is completed, obtain a phosphorus-containing flame retardant curing agent through purification operations.

[0010] As a preferred embodiment of the above solution, the molar ratio of the organophosphorus chloride, 2,4,6-tris(dimethylaminomethyl)phenol (DMP-30), and the acid-binding agent is 1:1-2.1:1-2.1.

[0011] As a preferred embodiment of the above solution, the acid-binding agent is mainly selected from one of triethylamine, pyridine, sodium hydroxide, sodium carbonate, etc.

[0012] As a preferred embodiment of the above solution, the reaction solvent is mainly selected from one of tetrahydrofuran, dichloromethane, chloroform, toluene, N,N-dimethylformamide, N,N-dimethylacetamide, etc. The amount of the reaction solvent can be appropriately adjusted according to the amount of the synthetic product, and the present invention does not make specific limitations.

[0013] As a preferred embodiment of the above solution, the organophosphorus chloride is mainly selected from one of diphenylphosphinous chloride, diphenylphosphorus chloride, diphenyl phosphorochloridate, 6-chloro-6H-dibenzo[c,e][1,2]phosphaphenanthrene-oxide, phenylphosphonic dichloride, or phenoxyphosphoryl dichloride, etc.

[0014] The present invention further provides an application of the phosphorus-containing flame retardant curing agent in curing epoxy resin.

[0015] As a preferred embodiment of the above solution, the application fields of the epoxy resin cured by the phosphorus-containing flame retardant curing agent include adhesives, coatings, electronic packaging materials, composite materials, etc.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] Using organophosphorus chloride and 2,4,6-tris(dimethylaminomethyl)phenol (DMP-30) as raw materials, through substitution reactions, construct a tertiary amine group with curing activity and a phosphorus-containing group with good flame retardant effect in one molecule to synthesize a class of phosphorus-containing flame retardant curing agents, which have good curing activity for epoxy resin, and the intrinsically flame-retardant epoxy resin materials obtained after curing have excellent flame retardant properties and mechanical properties. Specific Embodiments

[0018] To better understand the present invention, the content of the present invention will be further clarified below in conjunction with embodiments, but the present invention is not limited only to the following embodiments.

[0019] In the following examples, nitrogen is used as the protective gas. Other inert gases can also be used, and the present invention does not make specific limitations. Without special instructions, the experimental operations during the reaction (such as dropping, stirring, filtering, rotary evaporation, etc.) can be achieved by conventional technical means, and those skilled in the art can adjust according to actual needs.

[0020] Example 1

[0021] 0.1 mol of 2,4,6-tris(dimethylaminomethyl)phenol (DMP-30), 0.1 mol of triethylamine and 150 ml of tetrahydrofuran were mixed evenly in a reaction kettle, and nitrogen was continuously introduced; 0.1 mol of diphenylphosphinous chloride was dissolved in 100 ml of tetrahydrofuran, and then it was dropped into the reaction kettle at 25 °C under nitrogen and stirring conditions; after the dropping was completed, the reaction was stirred at 50 °C for 2 h; after the reaction was completed, through purification operations such as filtration and rotary evaporation, a phosphorus-containing flame retardant curing agent (No.: A) was obtained.

[0022] Example 2

[0023] 0.1 mol of 2,4,6-tris(dimethylaminomethyl)phenol (DMP-30), 0.1 mol of triethylamine and 150 ml of tetrahydrofuran were mixed evenly in a reaction kettle, and nitrogen was continuously introduced; 0.1 mol of diphenylphosphinous chloride was dissolved in 100 ml of tetrahydrofuran, and then it was dropped into the reaction kettle at 40 °C under nitrogen and stirring conditions; after the dropping was completed, the reaction was stirred at 65 °C for 5 h; after the reaction was completed, through purification operations such as filtration and rotary evaporation, a phosphorus-containing flame retardant curing agent (No.: B) was obtained.

[0024] Example 3

[0025] 0.1 mol of 2,4,6-tris(dimethylaminomethyl)phenol (DMP-30), 0.1 mol of triethylamine and 150 ml of tetrahydrofuran were mixed evenly in a reaction kettle, and nitrogen was continuously introduced; 0.1 mol of 6-chloro-6H-dibenz[c,e][1,2]oxaphosphinine 6-oxide was dissolved in 200 ml of tetrahydrofuran, and then it was dropped into the reaction kettle at 50 °C under nitrogen and stirring conditions; after the dropping was completed, the reaction was stirred at 80 °C for 8 h; after the reaction was completed, through purification operations such as filtration and rotary evaporation, a phosphorus-containing flame retardant curing agent (No.: C) was obtained.

[0026] Example 4

[0027] Mix 0.1 mol of 2,4,6-tris(dimethylaminomethyl)phenol (DMP-30), 0.1 mol of triethylamine and 150 ml of tetrahydrofuran evenly in a reaction kettle, and continuously introduce nitrogen; dissolve 0.1 mol of diphenyl phosphorochloridate in 100 ml of tetrahydrofuran, and then add it dropwise to the reaction kettle at 35 °C under nitrogen and stirring conditions; after the dropping is completed, stir and react at 70 °C for 6 h; after the reaction is completed, through purification operations such as filtration and rotary evaporation, a phosphorus-containing flame retardant curing agent (No.: D) is obtained.

[0028] Example 5

[0029] Mix 0.1 mol of 2,4,6-tris(dimethylaminomethyl)phenol (DMP-30), 0.1 mol of triethylamine and 150 ml of tetrahydrofuran evenly in a reaction kettle, and continuously introduce nitrogen; dissolve 0.05 mol of phenylphosphonic dichloride in 100 ml of tetrahydrofuran, and then add it dropwise to the reaction kettle at 45 °C under nitrogen and stirring conditions; after the dropping is completed, stir and react at 65 °C for 5 h; after the reaction is completed, through purification operations such as filtration and rotary evaporation, a phosphorus-containing flame retardant curing agent (No.: E) is obtained.

[0030] Example 6

[0031] Mix 0.1 mol of 2,4,6-tris(dimethylaminomethyl)phenol (DMP-30), 0.1 mol of triethylamine and 150 ml of tetrahydrofuran evenly in a reaction kettle, and continuously introduce nitrogen; dissolve 0.05 mol of phenoxyphosphoryl chloride in 100 ml of tetrahydrofuran, and then add it dropwise to the reaction kettle at 55 °C under nitrogen and stirring conditions; after the dropping is completed, stir and react at 70 °C for 6 h; after the reaction is completed, through purification operations such as filtration and rotary evaporation, a phosphorus-containing flame retardant curing agent (No.: F) is obtained.

[0032] Application Example: The phosphorus-containing flame retardant curing agents A-F prepared in Examples 1-6 are respectively mixed with bisphenol A epoxy resin (E-51 epoxy resin, brand CYD-128, Yueyang Baling Huaxing Petrochemical Co., Ltd.) in a mass ratio of 25:100. The limiting oxygen index (LOI) of the epoxy resin cured product is measured according to the ASTM D2863 standard, and the vertical burning test of the epoxy resin cured product is carried out according to the UL-94 test standard, as shown in Table 1. The mechanical properties of the epoxy resin cured product are measured according to the ASTM D3039 standard, as shown in Table 2.

[0033] Comparative example: 2,4,6-Tris(dimethylaminomethyl)phenol (DMP-30) and bisphenol A epoxy resin (E-51 epoxy resin, grade CYD-128, Yueyang Baling Huaxing Petrochemical Co., Ltd.) were mixed at a mass ratio of 15:100. The limiting oxygen index (LOI) of the epoxy resin cured product was measured according to the ASTM D2863 standard, and the vertical burning test of the epoxy resin cured product was carried out with reference to the UL-94 test standard, as shown in Table 1. The mechanical properties of the epoxy resin cured product were measured according to the ASTM D3039 standard, as shown in Table 2.

[0034] Table 1 Flame retardant performance parameters of epoxy resin cured products

[0035] Curing agent LOI (%) UL94 flame retardant rating DMP-30 20.5 No rating A 34.2 V-0 B 32.5 V-0 C 31.3 V-0 D 35.6 V-0 E 30.5 V-0 F 32.8 V-0

[0036] Table 2 Mechanical property parameters of epoxy resin cured products

[0037]

[0038] As can be seen from Table 1, the cured product obtained by curing epoxy resin with DMP-30 in the comparative example is a flammable material with poor flame retardant performance, while the cured product obtained by curing epoxy resin with curing agents A-F prepared in the present invention has excellent flame retardant performance. As can be seen from Table 2, the mechanical properties of the cured product obtained by curing epoxy resin with curing agents A-F prepared in the present invention not only do not decrease, but also have a significant improvement, and the mechanical properties are good.

[0039] The above are only the preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the inventive concept of the present invention, several improvements and transformations can be made, and these all belong to the protection scope of the present invention.

Claims

1. A phosphorus-containing flame retardant curing agent is obtained by a substitution reaction of an organophosphorus chloride and 2, 4, 6-tris(dimethylaminomethyl)phenol, and the substitution reaction includes: Mix 2,4,6-tris(dimethylaminomethyl)phenol, an acid-binding agent and a reaction solvent uniformly in a reaction kettle, and continuously introduce a protective gas. Then, dropwise add an organic solution of an organophosphorus chloride to the reaction kettle under the conditions of 25-70 °C, a protective gas and stirring. After the dropwise addition of the organic solution containing the organophosphorus chloride is completed, stir and react for 2-8 h under the condition of 50-80 °C. After the reaction is completed, a phosphorus-containing flame retardant curing agent is obtained through a purification operation. The organophosphorus chloride is selected from one of diphenylphosphinous chloride, diphenylphosphine chloride, diphenyl phosphorochloridate, 6-chloro-6H-dibenzo[c,e][1,2]phosphinine 6-oxide, phenylphosphonic dichloride or phenoxyphosphoryl dichloride.

2. A preparation method of a phosphorus-containing flame retardant curing agent, comprising: Mix 2,4,6-tris(dimethylaminomethyl)phenol, an acid-binding agent and a reaction solvent uniformly in a reaction kettle, and continuously introduce a protective gas. Then, dropwise add an organic solution of an organophosphorus chloride to the reaction kettle under the conditions of 25-70 °C, a protective gas and stirring. After the dropwise addition of the organic solution containing the organophosphorus chloride is completed, stir and react for 2-8 h under the condition of 50-80 °C. After the reaction is completed, a phosphorus-containing flame retardant curing agent is obtained through a purification operation. The organophosphorus chloride is selected from one of diphenylphosphinous chloride, diphenylphosphine chloride, diphenyl phosphorochloridate, 6-chloro-6H-dibenzo[c,e][1,2]phosphinine 6-oxide, phenylphosphonic dichloride or phenoxyphosphoryl dichloride.

3. The preparation method according to claim 2, wherein The molar ratio of the organophosphorus chloride, 2,4,6-tris(dimethylaminomethyl)phenol and the acid-binding agent is 1:1-2.1:1-2.

1.

4. The preparation method according to claim 2 or 3, characterized in that, The acid-binding agent is selected from one of triethylamine, pyridine, sodium hydroxide or sodium carbonate.

5. The preparation method according to claim 2, characterized in that, The reaction solvent is selected from one of tetrahydrofuran, dichloromethane, chloroform, toluene, N,N-dimethylformamide or N,N-dimethylacetamide.

6. Application of the phosphorus-containing flame retardant curing agent according to claim 1 in curing epoxy resin.

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