CN115948024A - Preparation method of a new type of low-cost biobasic flame-retardant epoxy resin material - Google Patents

Abstract

The invention discloses a preparation method of a novel low-cost biological basic flame-retardant epoxy resin material. And then, reacting the nitrogen-containing compound with the white precipitate to prepare the bio-based flame retardant PPM-MEL. The flame retardant can effectively improve the flame retardant property and the smoke suppression property of the material. And greatly improves the mechanical property of the material; compared with pure epoxy resin, the peak heat release rate, the total heat release amount, the smoke release rate and the carbon monoxide release rate of the epoxy resin are respectively reduced by 70.2%, 36.4%, 65.7% and 51.4% after the flame retardant is added, and the flexural modulus, the flexural strength and the limiting oxygen index of the material are respectively improved by 117.5%, 138.2% and 33.7%. The addition of the flame retardant greatly improves the smoke suppression and flame retardant properties and mechanical properties of the material, and the raw material has simple acquisition mode, low price, environmental protection and no pollution.

Description

Preparation method of a new type of low-cost biobasic flame-retardant epoxy resin material

technical field

The invention belongs to the technical fields of flame-retardant materials and polymer materials, and relates to a preparation method of a novel low-cost biobasic flame-retardant epoxy resin material.

Background technique

Epoxy resin (EP) is a widely used thermosetting polymer material, which is the polycondensation product of epichlorohydrin and bisphenol A or polyol. Due to its excellent chemical resistance, thermal stability, adhesive properties, mechanical properties and dimensional stability, it is widely used in construction, machinery, transportation, electronics industry and aerospace industry. However, while utilizing the excellent properties of this material, its flammability disadvantage also brings fire hazards, which limits its application in many aspects. With the development of social economy, people have put forward higher requirements for the flame retardancy and mechanical properties of EP. Therefore, endowing EP with higher flame retardancy and mechanical properties has long-term and profound significance.

Flame retardants are functional additives that endow flammable polymers with flame retardancy, mainly for the flame retardancy of polymer materials. Conventional flame retardants are halogen-containing flame retardants, but EP containing halogen elements will produce toxic gases when burned, which poses a threat to human life, health and safety. Therefore, halogen-containing flame retardants have become less and less. At present, more and more various halogen-free flame retardants have been developed and applied. DOPO and its derivatives, ammonium polyphosphate (APP) are common halogen-free flame retardants, which have been used to improve the flame retardancy of epoxy resins. performance. However, compared with these flame retardants, bio-based flame retardants are more environmentally friendly. They are extracted from green raw materials, with low cost and no pollution.

In recent years, inorganic flame retardants have been used more and more, such as magnesium hydroxide, aluminum hydroxide and calcium hydroxide, which are not only cheap, but also do not release smoke or produce harmful gases when burned. However, since such inorganic flame retardants are often added in large amounts and have poor compatibility with the polymer matrix, this will reduce the mechanical properties of the matrix. Therefore, it is necessary to organically modify the inorganic flame retardant to improve its dispersion in the polymer matrix, and to further enhance the flame retardancy, smoke suppression and mechanical properties of the polymer matrix.

Contents of the invention

Aiming at the above-mentioned defects existing in the prior art, the present invention provides a novel low-cost biobasic flame-retardant epoxy resin material preparation method, the purpose of which is to achieve simple preparation method, low cost, environmental protection, wide application, and good Flame retardant and smoke suppression properties, while improving mechanical properties.

In order to achieve the above object, the technical scheme adopted in the present invention is:

A kind of preparation method of novel low-cost biobasic flame retardant epoxy resin material, specifically comprises the following steps:

(1) Preparation of biobasic flame retardant:

S1. After anhydrous piperazine and bio-based organic acid were stirred and reacted at 80-100°C for 3-4h, metal hydroxide was added, refluxed at 80-100°C for 5-7h, filtered, washed and dried to obtain a preliminary improvement sexual product.

S2. Dissolve the nitrogen-containing compound in distilled water, adjust the pH to 5-6 with hydrochloric acid, add the preliminary modified product, react at 80-100°C for 6-10 hours, filter while hot, wash and dry to obtain a bio-based flame retardant PPM-MEL.

Wherein, the bio-based organic acid is one of alginic acid, diphenolic acid, tartaric acid and phytic acid.

Further, the metal hydroxide is one of magnesium hydroxide, aluminum hydroxide, and calcium hydroxide with a particle size of 100-500 nm.

Further, the nitrogen-containing compound is one of melamine, urea, and N-aminoethylpiperazine.

Preferably, the molar ratio of the anhydrous piperazine, bio-based organic acid and metal hydroxide is 4:1:1˜2:1:2.

Preferably, the mass ratio of the preliminary modified product to the nitrogen-containing compound is 1:0.5˜1:2.5.

(2) Preparation of biobasic flame retardant epoxy resin material:

S3. Disperse the above flame retardant PPM-MEL in absolute ethanol, add bisphenol A epoxy resin and curing agent diethylenetriamine and mix evenly, stir in a water bath at 50-80°C to remove air bubbles, and evaporate in a vacuum After the solvent is removed, the reaction mixture is pre-cured at 60-80°C for 1-2 hours, and cured at 100-120°C for 3-5 hours to prepare a novel biobasic flame-retardant epoxy resin material.

Preferably, the amount of the flame retardant PPM-MEL is 5-25% of the mass of the bisphenol A epoxy resin.

Preferably, the amount of the curing agent diethylenetriamine is 5-20% of the mass of the bisphenol A epoxy resin.

The structure and performance characterization of the new low-cost bio-basic flame-retardant epoxy resin material of the present invention:

Taking magnesium hydroxide as an example for the metal hydroxide being prepared, and melamine as an example for the nitrogen-containing compound, the structure and performance of the new low-cost biobasic flame-retardant epoxy resin material of the present invention are analyzed and explained.

Fig. 1 is the infrared spectrogram of the novel biobasic flame retardant prepared by the present invention. Compared with the PPM spectrum of MH (magnesium hydroxide) and the primary modified product, the characteristic peak of OH ^- at 3698cm ^-1 in MH disappeared. In the spectrum of PPM, the characteristic peak at 1087cm ^-1 comes from the CN bond stretching vibration of piperazine. The characteristic peak at 1467cm ^-1 is due to the bending vibration of -NH ₂ ⁺ . The broad peak at 3368 ^cm belongs to -OH in phytic acid. In the spectrum of MEL (melamine), the characteristic peaks at 3468cm ^-1 , 3417cm ^-1 , and 3130cm ^-1 belong to the amino group of MEL. However, in PPM-MEL, these peaks are shifted to 3411 cm ^-1 and 3123 cm ^-1 , and the peak at 3123 cm ^-1 is broadened due to the formation of -NH ₃ ⁺ -O- ionic bonds; -NH ₂ groups The ionic interaction between them causes the characteristic absorption peak of the triazine ring in MEL to shift from 1653cm ^-1 to 1668cm ^-1 . And protonation of the ring nitrogen causes the MEL peak at 816cm ^-1 to shift to 780cm ^-1 . It can be judged that the novel bio-based flame retardant of the present invention has been successfully prepared.

Fig. 2 is the oxygen index diagram of the novel low-cost biobasic flame-retardant epoxy resin composite material prepared by the present invention. It can be seen from Figure 2 that the limiting oxygen index of pure epoxy resin a is 19.0%, and b, c, d, and e in the figure are the intrinsic resistance of the flame retardant content of 5%, 10%, 15%, and 20%, respectively. The limiting oxygen index of the flame retardant epoxy resin composite increases with the increase of the amount of flame retardant; the limiting oxygen index of e is 25.4%, which is 33.7% higher than that of pure epoxy resin.

Fig. 3 is a carbon monoxide release rate diagram of a novel low-cost biobasic flame-retardant epoxy resin material prepared by the present invention. In the figure, a, b, c, d, and e are new low-cost biological products with the dosage of flame retardant PPM-MEL being 0%, 5%, 10%, 15%, and 20% of the mass of bisphenol A epoxy resin, respectively. Carbon monoxide release rate curves of fundamentally flame-retardant epoxy resin composites. Curve a represents the peak carbon monoxide release rate of pure epoxy resin at 0.035g/s, while in curves b, c, d, and e, the carbon monoxide release rate of the new low-cost biobasic flame-retardant epoxy resin material is significantly reduced. The peak carbon monoxide release rate of curve e is reduced to 0.017 g/s. The peak carbon monoxide release rate was reduced by 51.4%.

Figure 4 is a graph of the smoke release rate of the novel low-cost biobasic flame-retardant epoxy resin material prepared by the present invention. In the figure, a, b, c, d, and e are new low-cost bio-basic flame retardants whose dosages are 0%, 5%, 10%, 15%, and 20% of the mass of bisphenol A epoxy resin, respectively. Smoke release rate curves of epoxy resin composites. Curve a shows that the peak smoke release rate of pure epoxy resin is as high as 0.335m2/s. The peak smoke release rate decreased significantly with the increase of flame retardant content. Curve e shows the lowest peak smoke release rate of 0.115 m2/s. Compared with pure epoxy resin, the peak smoke release rate was reduced by 65.7%. The decrease of the smoke release rate means that the material has better smoke suppression performance.

Fig. 5 is a graph of the heat release rate of the novel low-cost biobasic flame-retardant epoxy resin material prepared by the present invention. In the figure, a, b, c, d, and e are new low-cost bio-basic flame retardants whose dosages are 0%, 5%, 10%, 15%, and 20% of the mass of bisphenol A epoxy resin, respectively. Heat release rate curves of epoxy resin composites. In curve a, the peak heat release rate of pure epoxy resin material is 1180.49Kw/m2. The peak heat release rate in curve e is reduced to 351.20Kw/m2, which is 70.2% lower. A decrease in the rate of heat release represents a decrease in the intensity of the combustion flame.

Fig. 6 is the total heat release of the novel low-cost biobasic flame-retardant epoxy resin material prepared by the present invention. In the figure, a, b, c, d, and e are new low-cost bio-basic flame retardants whose dosages are 0%, 5%, 10%, 15%, and 20% of the mass of bisphenol A epoxy resin, respectively. Total heat release from burning epoxy resin composites. In curve a, the total heat release of pure epoxy resin material is 88.26MJ/m2. The total heat release in curve e is reduced to 56.09MJ/m2, a decrease of 36.4%. The reduction of total heat release greatly reduces the harm caused by the burning of epoxy resin materials.

Fig. 7 is a diagram of the mechanical properties of the novel low-cost biobasic flame-retardant epoxy resin material prepared by the present invention. In the figure a, b, c, d, e are the bending strength and flexural modulus. The flexural modulus and flexural strength of the epoxy resin material a without flame retardant are 1.6±0.6GPa and 26.8±4MPa, respectively. Adding 20% flame retardant PPM-MEL epoxy resin material e had the highest flexural modulus and flexural strength, which were increased by 117.5% and 138.2%, respectively. The increase in bending strength means that the flame retardant has excellent compatibility with the epoxy resin matrix, which improves the mechanical properties of the epoxy resin material and can further broaden the scope of application of the epoxy resin.

Compared with prior art, the beneficial effect of the present invention is:

In the invention, the anhydrous piperazine is reacted with a bio-based organic acid, and the obtained product is subjected to an acid-base neutralization reaction with a metal hydroxide to obtain a preliminary modified product. A bio-based flame retardant, PPM-MEL, was prepared by reacting nitrogen-containing compounds with preliminary modified products. Anhydrous piperazine with low cost and high carbon content makes it have efficient char-forming ability. In the present invention, a low-cost bio-basic flame-retardant epoxy resin composite material is prepared by cross-linking a flame retardant with an epoxy resin. The flame retardant can effectively improve the flame-retardant performance and smoke suppression performance of the material, and greatly improve the the mechanical properties of the material. Compared with pure epoxy resin, the peak heat release rate, total heat release, smoke release rate, and carbon monoxide release rate of epoxy resin were reduced by 70.2%, 36.4%, 65.7%, and 51.4% after adding flame retardants. The flexural modulus, flexural strength and limiting oxygen index were increased by 117.5%, 138.2% and 33.7%, respectively. The addition of flame retardant greatly improves the smoke suppression, flame retardancy and mechanical properties of the material. In addition, bio-based raw materials are easy to obtain, cheap, environmentally friendly and pollution-free, and can be produced on a large scale.

Description of drawings

Fig. 1 is the infrared spectrogram of the novel low-cost biobasic flame retardant prepared by the present invention;

Fig. 2 is the oxygen index figure of the novel low-cost bio-basic flame-retardant epoxy resin material prepared by the present invention;

Fig. 3 is the carbon monoxide release rate figure of the novel low-cost biobasic flame-retardant epoxy resin material prepared by the present invention;

Fig. 4 is the smoke release rate figure of the novel low-cost biobasic flame-retardant epoxy resin material prepared by the present invention;

Fig. 5 is the heat release rate diagram of the novel low-cost biobasic flame-retardant epoxy resin material prepared by the present invention;

Fig. 6 is the total heat release figure of the novel low-cost biobasic flame-retardant epoxy resin material prepared by the present invention;

Fig. 7 is a diagram of the mechanical properties of the novel low-cost biobasic flame-retardant epoxy resin material prepared by the present invention.

Detailed ways

The preparation method and performance of the novel low-cost bio-basic flame-retardant epoxy resin material of the present invention will be further described below through specific examples.

Example 1

A kind of preparation method of novel low-cost biobasic flame retardant epoxy resin material, specifically comprises the following steps:

(1) Preparation of biobasic flame retardant:

Add 0.01mol phytic acid and 0.04mol anhydrous piperazine into a 500mL round-bottomed flask, raise the temperature to 90°C and keep it, and magnetically stir for 3h; when the temperature drops to 85°C, add deionized water as a solvent, stir for 5min, weigh Add 0.01mol magnesium hydroxide to it, react for 5 hours under stirring conditions, and obtain a white precipitate, filter and wash, and dry to obtain a preliminary modified product; dissolve 8g of melamine in boiling deionized water, adjust the pH to 5-6 with hydrochloric acid, and add 5.2g of the preliminary modified product was stirred and reacted at 90°C for 5h, filtered hot, washed three times, and dried in a vacuum oven at 80°C for 12h to obtain a white solid powder which was the flame retardant.

(2) Preparation of biobasic flame retardant epoxy resin material:

Disperse 3.0g of flame retardant in 20mL of absolute ethanol, add 25.22g of bisphenol A epoxy resin and 1.78g of diethylenetriamine in sequence, and stir the mixture in a water bath at 70°C under vacuum to remove bubbles. After evaporating the solvent in a vacuum, the reaction mixture was pre-cured in a mold at 80°C for 1 hour and cured at 120°C for 6 hours to obtain a flame-retardant epoxy resin material.

The performance test of embodiment 1 gained flame-retardant epoxy resin material:

Flame retardant performance: peak heat release rate is 731.22Kw/m ² , smoke release rate is 0.197m ² /s, total heat release is 70.75MJ/m ² , total smoke release is 19.33m ² , carbon monoxide release rate is 0.043 g/s;

Mechanical properties: the flexural modulus is 2.32±0.5GPa, and the flexural strength is 38.34±15.5MPa.

Example 2

A kind of preparation method of novel low-cost biobasic flame retardant epoxy resin material, specifically comprises the following steps:

(1) Preparation of biobasic flame retardant:

Add 0.01mol phytic acid and 0.02mol anhydrous piperazine into a 500mL round-bottomed flask, raise the temperature to 90°C and keep it, and magnetically stir for 3h; when the temperature drops to 85°C, add deionized water as a solvent, stir for 5min, weigh Add 0.02mol of magnesium hydroxide to it, react for 5 hours under stirring conditions, and obtain a white precipitate, filter and wash, and dry to obtain a preliminary modified product; dissolve 11g of melamine in boiling deionized water, adjust the pH to 5-6 with hydrochloric acid, and add 5.6g of the preliminary modified product was stirred and reacted at 90°C for 5h, filtered hot, washed 3 times, and dried in a vacuum oven at 80°C for 12h to obtain a white solid powder which was the flame retardant.

(2) Preparation of biobasic flame retardant epoxy resin material:

Disperse 4.5g of flame retardant in 20mL of absolute ethanol, add 23.72g of bisphenol-A epoxy resin and 1.78g of diethylenetriamine in sequence, and stir the mixture in a water bath at 70°C under vacuum to defoam. After evaporating the solvent in a vacuum, the reaction mixture was pre-cured in a mold at 80°C for 1 hour and cured at 120°C for 6 hours to obtain a flame-retardant epoxy resin material.

The performance test of embodiment 2 gained flame-retardant epoxy resin material:

Flame retardant performance: peak heat release rate is 513.58Kw/m ² , smoke release rate is 0.195m ² /s, total heat release is 55.78MJ/m ² , total smoke release is 15.72m ² , carbon monoxide release rate is 0.041 g/s;

Mechanical properties: the flexural modulus is 3.08±0.8GPa, and the flexural strength is 50.88±12.8MPa.

Example 3

A kind of preparation method of novel low-cost biobasic flame retardant epoxy resin material, specifically comprises the following steps:

(1) Preparation of biobasic flame retardant:

Add 0.01mol phytic acid and 0.04mol anhydrous piperazine into a 500mL round-bottomed flask, raise the temperature to 90°C and keep it, and magnetically stir for 3h; when the temperature drops to 85°C, add deionized water as a solvent, stir for 5min, weigh Add 0.02mol of magnesium hydroxide to it, react for 5 hours under stirring conditions, and obtain a white precipitate, filter and wash, and dry to obtain a preliminary modified product; dissolve 13g of melamine in boiling deionized water, adjust the pH to 5-6 with hydrochloric acid, and add 6.4g of the preliminary modified product was stirred and reacted at 90°C for 5h, filtered hot, washed three times, and dried in a vacuum oven at 80°C for 12h to obtain a white solid powder which was the flame retardant.

(2) Preparation of biobasic flame retardant epoxy resin material:

Disperse 6.0g of flame retardant in 20mL of absolute ethanol, add 22.22g of bisphenol A epoxy resin and 1.78g of diethylenetriamine in sequence, and stir the mixture in a water bath at 70°C under vacuum to defoam. After evaporating the solvent in a vacuum, the reaction mixture was pre-cured in a mold at 80°C for 1 hour and cured at 120°C for 6 hours to obtain a flame-retardant epoxy resin material.

The performance test of embodiment 3 gained flame-retardant epoxy resin material:

Flame retardant performance: peak heat release rate is 351.20Kw/m ² , smoke release rate is 0.124m ² /s, total heat release is 56.08MJ/m ² , total smoke release is 14.23m ² , carbon monoxide release rate is 0.015 g/s;

Mechanical properties: the flexural modulus is 3.48±0.9GPa, and the flexural strength is 63.84±9.1MPa.

Claims (8)

1. A preparation method of a novel low-cost biological basic flame-retardant epoxy resin material is characterized by comprising the following steps: the method comprises the following steps:

(1) Preparation of bio-based intrinsic flame retardant:

s1, stirring anhydrous piperazine and bio-based organic acid at 80-100 ℃ to react for 3-4 h, adding metal hydroxide, refluxing for 5-7 h at 80-100 ℃, filtering, washing and drying to obtain a primary modified product;

s2, dissolving a nitrogen-containing compound in distilled water, adjusting the pH to 5-6 by using hydrochloric acid, adding the primary modified product, reacting at 80-100 ℃ for 6-10 h, filtering while hot, washing and drying to obtain a bio-based flame retardant PPM-MEL;

(2) The preparation of the bio-based intrinsic flame-retardant epoxy resin material comprises the following steps:

s3, dispersing the flame retardant PPM-MEL in absolute ethyl alcohol, adding bisphenol A type epoxy resin and a curing agent diethylenetriamine, uniformly mixing, carrying out vacuum stirring and defoaming in a water bath at 50-80 ℃, carrying out vacuum solvent evaporation, precuring the reaction mixture for 1-2h at 60-80 ℃, and curing for 3-5 h at 100-120 ℃ to obtain the novel low-cost bio-based intrinsic flame-retardant epoxy resin material.

2. The preparation method of the novel low-cost biological basic flame-retardant epoxy resin material as claimed in claim 1, wherein the preparation method comprises the following steps: in the step (1), the bio-based organic acid is one of alginic acid, diphenolic acid, tartaric acid and phytic acid.

3. The preparation method of the novel low-cost biological basic characteristic flame-retardant epoxy resin material according to claim 1 or 2, characterized by comprising the following steps: in the step (1), the metal hydroxide is one of magnesium hydroxide, aluminum hydroxide and calcium hydroxide with the particle size of 100-500 nm.

4. The preparation method of the novel low-cost biological basic characteristic flame-retardant epoxy resin material as claimed in claim 3, characterized in that: in the step (1), the molar ratio of the anhydrous piperazine, the bio-based organic acid and the metal hydroxide is 4.

5. The preparation method of the novel low-cost biological basic characteristic flame-retardant epoxy resin material according to claim 1, 2 or 4, characterized by comprising the following steps: in the step (1), the nitrogen-containing compound is one of melamine, urea and N-aminoethyl piperazine.

6. The preparation method of the novel low-cost biological basic flame retardant epoxy resin material as claimed in claim 5, wherein the preparation method comprises the following steps: in the step (1), the mass ratio of the primary modified product to the nitrogen-containing compound is 1.

7. The preparation method of the novel low-cost biological basic characteristic flame-retardant epoxy resin material according to claim 1 or 6, characterized by comprising the following steps: in S3, the dosage of the flame retardant PPM-MEL is 5-25% of the mass of the bisphenol A type epoxy resin.

8. The preparation method of the novel low-cost biological basic flame retardant epoxy resin material as claimed in claim 7, wherein the preparation method comprises the following steps: in S3, the consumption of the curing agent diethylenetriamine accounts for 5-20% of the mass of the bisphenol A epoxy resin.

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