1. The preparation method of the phosphazene and imine composite flame retardant is characterized by comprising the following steps: the method comprises the following steps:

reacting hydroxybenzaldehyde, triethylamine, hexachlorocyclotriphosphazene and a first part of 1, 4-dioxane at 85-95 ℃ for 11-13 hours to obtain an aldehyde end-capped intermediate product with hexafunctionality;

the compound flame retardant is obtained by continuously reacting p-phenylenediamine, a second part of 1, 4-dioxane and the intermediate product at 85-95 ℃ for 11-13 h.

2. The method of claim 1, wherein: wherein, include: 130 parts of parahydroxybenzaldehyde 125-one, 90-105 parts of triethylamine and 50-60 parts of hexachlorocyclotriphosphazene; and/or 70-80 parts by mass of p-phenylenediamine and 10-12 parts by mass of intermediate product.

3. The method of claim 2, wherein: preferably, the method comprises the following steps: 130 parts of p-hydroxybenzaldehyde, 90 parts of triethylamine and 50 parts of hexachlorocyclotriphosphazene; and/or 75 parts by mass of p-phenylenediamine and 10 parts by mass of intermediate product.

4. The method of claim 1, wherein: the reaction for obtaining the aldehyde-terminated intermediate product with six functionalities is carried out under the protection of inert gas.

5. The method of claim 1, wherein: wherein, the p-phenylenediamine and the second part of 1, 4-dioxane are uniformly mixed, and then the intermediate product is added; and/or the intermediate product and 1, 4-dioxane are firstly prepared into a solution and then added for reaction.

6. The composite flame retardant prepared by the preparation method according to any one of claims 1 to 5.

7. Phosphazene and imine composite flame-retardant epoxy resin material, which is characterized in that: it includes: the composite flame retardant according to claim 6, a bisphenol A epoxy resin and an organic amine curing agent.

8. The epoxy material of claim 7, wherein: the preparation method comprises the following raw materials: the composite flame retardant is not more than 1 part by mass, the bisphenol A type epoxy resin is 100-110 parts by mass, and the organic amine curing agent is 4,4' -diaminodiphenylmethane is 18-26 parts by mass.

9. The method for preparing an epoxy resin material according to claim 7 or 8, characterized in that: the method comprises the following steps: and uniformly mixing the composite flame retardant, the bisphenol A type epoxy resin and the 4,4' -diaminodiphenylmethane, and heating and curing at the temperature of 100-150 ℃ to obtain the epoxy resin material.

10. The method of claim 9, wherein: the curing comprises the following steps: curing at 100 ℃ for 1h and then at 150 ℃ for 2 h.

Background

Epoxy resin is a thermosetting resin material with good comprehensive performance, and is widely applied to various aspects such as adhesives, electrical insulation, coatings, composite materials and the like. However, epoxy resin is extremely easy to burn and can continuously and violently spontaneously combust after leaving fire, and the performance defect needs modification optimization.

At present, the most common way for modifying flame retardance is to add sufficient additive flame retardant into a matrix, but the traditional flame retardant needs a large addition amount to ensure an ideal flame retardant effect, so that the compatibility of the flame retardant and the resin matrix is poor, the flame retardant effect of the material is influenced, and the mechanical property of the material is also deteriorated due to the introduction of a weak chemical bond in a system.

On the other hand, the synergistic flame-retardant system can effectively improve the thermal stability, flame-retardant property and mechanical property of matrix resin, but the problems of high cost, difficult dispersion and the like still exist in practical application.

Disclosure of Invention

The invention aims to provide a composite flame-retardant epoxy resin which has good compatibility of a composite system, excellent flame-retardant property, thermal stability and mechanical property of a material and a synergistic flame-retardant effect, and a preparation method thereof.

The invention firstly provides the following technical scheme:

the preparation method of the phosphazene and imine composite flame retardant comprises the following steps:

reacting hydroxybenzaldehyde, triethylamine, hexachlorocyclotriphosphazene and a first part of 1, 4-dioxane at 85-95 ℃ for 11-13 hours to obtain an aldehyde end-capped intermediate product with hexafunctionality;

the compound flame retardant is obtained by continuously reacting p-phenylenediamine, a second part of 1, 4-dioxane and the intermediate product at 85-95 ℃ for 11-13 h.

According to some preferred embodiments of the invention, the preparation method comprises: 130 parts of parahydroxybenzaldehyde 125, 90-105 parts of triethylamine and 50-60 parts of hexachlorocyclotriphosphazene.

According to some preferred embodiments of the invention, the preparation method comprises: 70-80 parts of p-phenylenediamine and 10-12 parts of intermediate product.

According to some preferred embodiments of the invention, the preparation method comprises: 130 parts of p-hydroxybenzaldehyde, 90 parts of triethylamine and 50 parts of hexachlorocyclotriphosphazene.

According to some preferred embodiments of the invention, the preparation method comprises: 75 parts by mass of p-phenylenediamine and 10 parts by mass of the intermediate product.

According to some preferred embodiments of the present invention, the obtaining reaction of the hexa-functional aldehyde-terminated intermediate product is carried out under an inert gas atmosphere.

According to some preferred embodiments of the present invention, in the preparation method, the p-phenylenediamine and the second part of 1, 4-dioxane are uniformly mixed, and then the intermediate product is added.

According to some preferred embodiments of the present invention, in the preparation method, the intermediate product is prepared as a solution with 1, 4-dioxane and then added for reaction.

The invention further provides the composite flame retardant prepared by the preparation method.

According to specific embodiments, the composite flame retardant is a novel polyaminophosphazene derivative.

The invention further provides a composite flame-retardant epoxy resin material containing the composite flame retardant, which comprises the following components: the composite flame retardant, bisphenol A epoxy resin and organic amine curing agent.

According to some preferred embodiments of the present invention, the epoxy material further comprises the following raw materials: the composite flame retardant is not more than 1 part by mass, the bisphenol A type epoxy resin is 100-110 parts by mass, and the organic amine curing agent is 4,4' -diaminodiphenylmethane is 18-26 parts by mass.

The invention further provides a preparation method of the composite flame-retardant epoxy resin material, which comprises the following steps: and uniformly mixing the composite flame retardant, the bisphenol A type epoxy resin and the 4,4' -diaminodiphenylmethane, and heating and curing at the temperature of 100-150 ℃ to obtain the epoxy resin material.

According to some preferred embodiments of the invention, the curing comprises: curing at 100 ℃ for 1h and then at 150 ℃ for 2 h.

The composite flame retardant is a reactive flame retardant with a phosphazene/aromatic imine composite structure, the tail end of which contains polyfunctional active amino, wherein C ═ N bonds and phosphazene ring structures contain P, N flame retardant elements, the purpose of high-efficiency flame retardance can be realized under the synergistic flame retardant effect, and the composite flame retardant has a particularly excellent flame retardant effect on bisphenol A epoxy resin; meanwhile, the flame retardant can directly participate in forming a polymer network through reactive grafting of terminal active amino groups, so that the flame retardant has good compatibility and excellent intrinsic flame retardant property with an epoxy resin matrix.

The preparation method adopts hexachlorocyclotriphosphazene, p-hydroxybenzaldehyde and p-phenylenediamine as raw materials, synthesizes a novel polyamino phosphazene derivative as a target flame retardant of epoxy resin through a series of nucleophilic substitution and condensation reactions, compounds the derivative with the epoxy resin, and then carries out thermosetting by using an organic amine curing agent DDM (dichloro-diphenyl-methane), and a series of flame-retardant epoxy resin composite materials can be prepared by controlling the proportion.

Compared with the addition type phosphazene flame retardant in the prior art, the phosphazene/imine reaction type composite flame retardant has better compatibility with an epoxy resin matrix, better mechanical property of a product and better flame retardant effect.

Drawings

FIG. 1 is an IR comparison spectrum of the intermediates PZ-CHO and PAA described in the examples.

FIG. 2 shows PAA of the embodiment¹H-NMR and³¹P-NMR comparison spectrum.

Detailed Description

The present invention is described in detail below with reference to the following embodiments and the attached drawings, but it should be understood that the embodiments and the attached drawings are only used for the illustrative description of the present invention and do not limit the protection scope of the present invention in any way. All reasonable variations and combinations that fall within the spirit of the invention are intended to be within the scope of the invention.

According to the technical scheme of the invention, a specific implementation mode comprises the following steps:

(1) taking 130 parts by mass of p-hydroxybenzaldehyde 125-one, 90-105 parts by mass of triethylamine, 50-60 parts by mass of hexachlorocyclotriphosphazene and a proper amount of 1, 4-dioxane to react in a three-neck flask at 85-95 ℃ for 11-13 hours to obtain a hexa-functionality aldehyde end-capped intermediate product PZ-CHO, wherein the reaction formula is as follows:

(2) taking 70-80 parts by mass of p-phenylenediamine and a proper amount of 1, 4-dioxane to be put in a three-neck flask, adding 10-12 parts by mass of an intermediate product PZ-CHO, and continuously reacting for 11-13h at 85-95 ℃ to obtain a flame retardant PAA, wherein the further reaction formula is as follows:

(3) taking 0-1 part by mass of the obtained flame retardant (PAA) and 100-110 parts by mass of bisphenol A epoxy resin, fully mixing in a three-neck flask, then adding 18-26 parts of 4,4' -diaminodiphenylmethane (DDM), uniformly mixing, transferring into a mold, and heating and curing to obtain a product;

further, nitrogen can be used for protection during the reaction in the step (1);

furthermore, the dosage of the 1, 4-dioxane is twice of that of the p-hydroxybenzaldehyde.

Further, after the reaction in the step (1) is finished, filtering and drying an intermediate product PZ-CHO, and then performing the step (2);

further, in the step (2), p-phenylenediamine and 1, 4-dioxane can be uniformly mixed, and then PZ-CHO is added;

further, in the step (2), PZ-CHO and 1, 4-dioxane can be prepared into a solution and then added;

further, after the reaction in the step (2) is finished, the product can be filtered and washed by ethanol.

Further, in the step (3), when the product is poured into a mold, the mold can be preheated at 100 ℃;

further, the curing conditions in the step (3) are preferably 1 hour at 100 ℃ and 2 hours at 150 ℃.

The invention further provides the following examples (in which parts are parts by mass) and the resulting products were tested as follows:

and (3) testing tensile property:

the tensile properties of the materials were measured by an Instron 5967 Universal Material testing machine using ASTM D638-14 with a test environment temperature of 20. + -. 5 ℃ and humidity of 30. + -. 5% and a tensile load rate set at 5 mm/min. The tensile sample strips are dumbbell-shaped strips, the thickness of the middle parallel section is 2.5mm, and the number of the samples in each group is 10.

LOI test:

according to the GB/T2406-80, ASTM D2863-97 and other standards, igniting the sample bar by using a methane igniter under a stable nitrogen and oxygen atmosphere, quickly removing the sample bar, regulating the oxygen flow in the nitrogen-oxygen mixed flow by observing the stable combustion of the sample bar for 3min or the combustion length of the sample bar for 50mm, and repeating the operation until the limit oxygen index value of the sample bar is finally determined.

And (3) infrared testing:

structural change is tested by a VERTEX 70 Fourier infrared spectrometer, samples are prepared by a potassium bromide tabletting method, the resolution is 4cm < -1 >, the scanning range is 4000-400 cm < -1 >, and the scanning times are 32 times.

Nuclear magnetic resonance analysis:

the samples were tested for hydrogen (1H-NMR) and phosphorus (31P-NMR) spectra by AVANCE Digital 400 superconducting NMR spectrometer using deuterated dimethyl sulfoxide (DMSO-d6) as solvent, and Tetramethylsilane (TMS) was selected as internal standard.

Example 1

(1) Taking 130 parts of p-hydroxybenzaldehyde, 90 parts of triethylamine, 50 parts of hexachlorocyclotriphosphazene and 130 parts of 1, 4-dioxane to react in a three-neck flask at 90 ℃ for 12 hours to obtain an aldehyde-terminated intermediate product PZ-CHO with six functionality;

(2) taking 70 parts of p-phenylenediamine and 50 parts of 1, 4-dioxane into a three-neck flask, adding 10 parts of intermediate product PZ-CHO, and continuing to react for 12 hours to obtain a flame retardant PAA;

(3) 0.2 part of fire retardant PAA and 100 parts of bisphenol A epoxy resin with the model number of E-44(6101) are taken to be fully mixed in a three-neck flask, 20 parts of 4,4' -diaminodiphenylmethane (DDM) are added to be uniformly mixed, and then the mixture is moved into a mould to be heated and cured, thus obtaining the product.

Example 2

(1) Taking 130 parts of p-hydroxybenzaldehyde, 90 parts of triethylamine, 50 parts of hexachlorocyclotriphosphazene and 130 parts of 1, 4-dioxane to react for 12 hours at 90 ℃ in a three-neck flask to obtain an aldehyde-terminated intermediate product PZ-CHO with six functionality;

(2) taking 70 parts of p-phenylenediamine and 50 parts of 1, 4-dioxane into a three-neck flask, adding 10 parts of intermediate product PZ-CHO, and continuing to react for 12 hours to obtain a flame retardant PAA;

(3) 0.4 part of PAA and 100 parts of bisphenol A epoxy resin with the model number of E-44(6101) are taken to be fully mixed in a three-neck flask, then 20 parts of 4,4' -diaminodiphenylmethane are added, and after being uniformly mixed, the mixture is moved into a mould to be heated and cured, thus obtaining the product.

Example 3

(1) Taking 130 parts of p-hydroxybenzaldehyde, 90 parts of triethylamine, 50 parts of hexachlorocyclotriphosphazene and 130 parts of 1, 4-dioxane to react for 12 hours at 90 ℃ in a three-neck flask to obtain an aldehyde-terminated intermediate product PZ-CHO with six functionality;

(2) taking 70 parts of p-phenylenediamine and 50 parts of 1, 4-dioxane into a three-neck flask, adding 10 parts of intermediate product PZ-CHO, and continuing to react for 12 hours to obtain a flame retardant PAA;

(3) 0.6 part of flame retardant (PAA) and 100 parts of bisphenol A epoxy resin with the model number of E-44(6101) are taken and fully mixed in a three-neck flask, 20 parts of 4,4' -diaminodiphenylmethane (DDM) are added and evenly mixed, and then the mixture is moved into a mould to be heated and cured, thus obtaining the product.

Comparative example 1

And (2) taking 100 parts of bisphenol A epoxy resin, fully mixing in a three-neck flask, adding 20 parts of 4,4' -diaminodiphenylmethane (DDM), uniformly mixing, transferring into a mold, and heating and curing to obtain the epoxy resin material.

The products and intermediates of examples 1-3 and comparative example 1 were tested and the results are as follows:

in the infrared spectra of the intermediate PZ-CHO and PAA shown in the attached FIG. 1, the infrared spectra of the intermediate PZ-CHO and the flame retardant PAA are 3500cm at 3300-^-1In the middle ofA broader peak, corresponding to the characteristic absorption of hydroxyl (-OH), at 2800 and 3000cm^-1In the range of CH₂CH absorption of stretching vibration at 1270cm^-1、1178cm^-1The left and right peaks are from the absorption response of the phosphazene ring (P-N, P ═ N), 1042cm^-1The stronger peak at this position is the absorption peak of P-O-Ar, and the peak at 1720cm for PZ-CHO can be seen by comparing the characteristic peaks of PZ-CHO and PAA before and after the reaction^-1Disappearance of characteristic absorption peak of carbonyl (C ═ O) corresponding thereto, and 1619cm in PAA^-1The peak of stretching vibration of imine bond (C ═ N) appears at 1600-1500 cm^-1The obvious bifurcation peak is the respiratory vibration of the skeleton of the benzene ring (Ar), and the out-of-plane bending vibration of the skeleton is expressed in 800cm^-1The strong absorption bands at the left and right sides can be judged as para-disubstituted, the bending vibration of aromatic primary amine group (N-H) in PAA and the skeleton vibration of benzene ring are overlapped, but the peak is 3300cm^-1The presence of amine groups can be demonstrated by the presence of multiple absorption peaks before and after.

Of PAA shown in FIG. 2¹H-NMR and³¹in the P-NMR spectrum, the characteristic peaks are as follows:

¹HNMR(DMSO-d6)：8.7-8.5ppm(s，1H，-CH＝N-)，6.4-7.8ppm(m，8H，Ph-H)，5.4-5.1ppm(s，2H，-NH2-)；

³¹P NMR(DMSO-d6)：8.7ppm(s)；

in that¹In the H-NMR spectrum, the strong peak between 8.7-8.5ppm represents the hydrogen atom directly connected to the imine bond, the multiple peaks at 6.4-7.8ppm are due to the proton resonance at different positions on the benzene ring, while the chemical shift of the amine group with larger polarity is in the range of 5.4-5.1ppm biased to the high field direction³¹In the spectrum of P-NMR, a strong single resonance peak of one phosphorus atom appears only at δ ═ 8.7ppm, which indicates that the phosphorus atoms in PAA are all in the same chemical environment.

By FTIR,¹H-NMR and³¹the comprehensive analysis of the P-NMR result can obtain that the invention successfully prepares the fire retardant PAA with a target structure.

The tensile strength and limiting oxygen index of the product obtained in each example are shown in the following table:

table-product test data comparison

	Tensile strength (Mpa)	LOI(％)
			Example 1	79.4	23.0
Example 2	80.9	24.9
			Example 3	81.2	26.7
Comparative example 1	62.3	16.2

Comparing the limiting oxygen index values of examples 1, 2 and 3 and comparative example 1, it can be seen that the epoxy resin without the flame retardant has extremely poor flame retardant performance, the epoxy resin can be burnt when the oxygen concentration is 16.2%, and the LOI of the epoxy resin is remarkably improved after the flame retardant is added; in addition, the LOI value of the epoxy resin is increased along with the increase of the content of the flame retardant, and is increased from 23.0 percent to 26.7 percent; and the oxygen index of the PAA epoxy resin which is not added is only 20.8 percent, and the flame retardance is poor, which reflects the good flame retardance of the flame retardant PAA.

By comparing the tensile strengths of examples 1, 2, 3 and comparative example 1, it can be seen that the tensile strength was lower without the addition of the epoxy resin. After the flame retardant is added, the strength of the epoxy resin pull rope is greatly improved and is increased along with the increase of the addition amount of the PAA, because the flame retardant PAA has larger molecular weight and contains more rigid structures such as benzene rings, phosphazene rings and the like to participate in curing to form a cross-linked network, the content of the PAA is increased, the more benzene rings and phosphazene structures are, the larger the steric hindrance is, the movement of a molecular chain segment is blocked, and the breaking strength is increased.

The above examples are merely preferred embodiments of the present invention, and the scope of the present invention is not limited to the above examples. All technical schemes belonging to the idea of the invention belong to the protection scope of the invention. It should be noted that modifications and embellishments within the scope of the invention may be made by those skilled in the art without departing from the principle of the invention, and such modifications and embellishments should also be considered as within the scope of the invention.