WO2021139651A1

WO2021139651A1 - Biomass intrinsic flame-retardant high-temperature-resistant epoxy resin and preparation method therefor

Info

Publication number: WO2021139651A1
Application number: PCT/CN2021/070327
Authority: WO
Inventors: 戴李宗; 彭超华; 陈婷; 陈国荣; 何凯斌; 曾碧榕; 许一婷; 袁丛辉; 罗伟昂
Original assignee: 厦门大学
Priority date: 2020-01-07
Filing date: 2021-01-05
Publication date: 2021-07-15
Also published as: CN111138633B; CN111138633A

Abstract

Disclosed are a biomass intrinsic flame-retardant high-temperature-resistant epoxy resin and a preparation method therefor. The structural formula of a monomer of the epoxy resin is formula (I). In the present invention, a benzimidazole-like structure is introduced, which itself has an efficient solid-phase flame retardant effect, and which can promote the formation of a carbon layer, which improves the flame retardant performance of the epoxy resin; by introducing the benzimidazole-like structure into the epoxy resin, the benzimidazole-like structure is rigid and a nitrogen atom of a heterocyclic ring can form a hydrogen bond with a side hydroxyl group of the epoxy resin, which will greatly improve the heat resistance of the epoxy resin; and phosphorus-containing and halogen-containing elements are not introduced, and the selected raw material is a biomass platform product, such that the finally obtained epoxy resin is green and environmentally friendly.

Description

Biomass intrinsic flame-retardant and high-temperature resistant epoxy resin and preparation method thereof

Technical field

The invention belongs to the technical field of epoxy resins, and specifically relates to a biomass intrinsic flame-retardant and high-temperature resistant epoxy resin and a preparation method thereof.

Background technique

Epoxy resin is widely used in coatings, composite materials, electronic packaging, adhesives and other fields due to its outstanding comprehensive properties. And its flammable shortcomings greatly limit its popularization and application in some fields. At present, there are two main methods for flame retardant epoxy. One is to add flame retardant to epoxy resin. However, this method often causes flame retardant migration to cause flame retardant performance failure, or due to excessive addition. Unfavorable phenomena such as deterioration of mechanical properties of epoxy matrix. In order to avoid the above problems, the second method of flame retardant epoxy came into being. That is, by introducing flame-retardant elements into the epoxy monomer or curing agent, the intrinsic flame-retardant epoxy resin is synthesized. However, the existing monomers or curing agents containing flame-retardant elements are prepared from petrochemical products. In addition, flame retardant elements often contain phosphorus, but the combustion of such flame retardants will release a large amount of toxic smoke. With the depletion of petroleum resources, bio-based materials have attracted more and more attention from researchers. How to use biological materials to synthesize intrinsically high thermal stability and flame retardant epoxy resin is an urgent problem to be solved.

Summary of the invention

The purpose of the present invention is to overcome the defects of the prior art and provide a biomass intrinsic flame-retardant and high-temperature resistant epoxy resin.

Another object of the present invention is to provide a method for preparing the above biomass intrinsic flame-retardant and high-temperature resistant epoxy resin.

The technical scheme of the present invention is as follows:

A kind of biomass intrinsic flame-retardant and high-temperature resistant epoxy resin, the structural formula of its monomer is

Where R is

The preparation method of the above-mentioned biomass intrinsic flame-retardant and high-temperature resistant epoxy resin includes the following steps:

(1) Add o-phenylenediamine and aromatic aldehyde compounds to the organic solvent, then add sodium metabisulfite to the reactor, stir and react at 60～140℃ for 4～8h, precipitate with excess ice water, filter the precipitate, Washing and drying under reduced pressure to obtain a benzimidazole intermediate; the above aromatic aldehyde compound is o-vanillin, ethyl vanillin, vanillin, syringaldehyde or p-hydroxybenzaldehyde;

(2) The above-mentioned benzimidazole intermediate and epichlorohydrin are added to a mixed solvent composed of ethanol and water in a volume ratio of 2-4:1-3, and the ring-opening reaction is carried out at 50-100°C. 2- 8h, add excess acetone to stop the ring-opening reaction;

(3) Add sodium hydroxide solution dropwise to the material obtained in step (2), carry out the ring-closing reaction at 60-90°C for 2-8 hours, separate and remove the brine, use deionized water fully, and then use anhydrous sulfuric acid After removing water from manganese, the solvent is removed by rotary evaporation under reduced pressure to obtain the monomer;

(4) The above monomers are cured at 110-125°C for 1.5-2.5 hours, and post-cured at 175-185°C for 1.5-2.5 hours to obtain the biomass intrinsic flame-retardant and high-temperature resistant epoxy resin.

In a preferred embodiment of the present invention, the organic solvent is at least one of ethanol, N,N-dimethylformamide, acetonitrile and methanol.

Further preferably, the ratio of the organic solvent to the solute therein is 9-11 mL:1g.

In a preferred embodiment of the present invention, the ratio of the mixed solvent to the solute therein is 9-11 mL:1g.

In a preferred embodiment of the present invention, in the step (1), the molar ratio of o-phenylenediamine to aromatic aldehyde compound is 1:1-2.

In a preferred embodiment of the present invention, in the step (1), the sodium metabisulfite and o-phenylenediamine are equimolar.

In a preferred embodiment of the present invention, in the step (2), the molar ratio of the benzimidazole intermediate to epichlorohydrin is 1:5-10.

In a preferred embodiment of the present invention, in the step (3), the molar ratio of the sodium hydroxide to the benzimidazole intermediate is 5-10:1.

Further preferably, the concentration of the sodium hydroxide solution is 8-11%.

The beneficial effects of the present invention are:

1. The present invention introduces a benzimidazole-like structure, which itself has a high-efficiency solid-phase flame-retardant effect, which can promote the formation of a carbon layer and improve the flame-retardant performance of epoxy resin.

2. The present invention introduces the benzimidazole-like structure into the epoxy resin. The rigid structure of the benzimidazole-like structure and the heterocyclic nitrogen atoms can form hydrogen bonds with the epoxy resin side hydroxyl groups, which will greatly improve the epoxy resin Heat resistance.

3. The present invention does not introduce phosphorus and halogen elements, and the selected raw materials are biomass platform products, and the finally obtained epoxy resin is green and environmentally friendly.

Description of the drawings

Figure 1 is a hydrogen NMR spectrum of the benzimidazole intermediate obtained in Example 1 of the present invention.

2 is a hydrogen nuclear magnetic spectrum of the monomer of the biomass intrinsic flame-retardant and high-temperature resistant epoxy resin prepared in Example 1 of the present invention.

Fig. 3 is a graph showing the thermogravimetric curve of the resin obtained after curing the biomass intrinsic flame-retardant high-temperature resistant epoxy resin and bisphenol A epoxy resin prepared in Example 1 of the present invention through diaminodiphenylmethane under a nitrogen atmosphere.

Detailed ways

The technical solutions of the present invention will be further illustrated and described below through specific implementations in conjunction with the accompanying drawings.

Example 1

(1) Add o-phthalamide and o-vanillin to N,N-dimethylformamide at a molar ratio of 1:1, and then add sodium metabisulfite equimolar to o-phthalamide into the reactor, The ratio of N,N-dimethylformamide to the solute in it is 10mL:1g, stirred at 130℃ for 6h, precipitated with excess ice water, filtered the precipitate, washed and dried under reduced pressure to obtain the result as shown in Figure 1. The benzimidazole intermediate of the hydrogen NMR spectrum;

(2) Add the above-mentioned benzimidazole intermediate and epichlorohydrin in a molar ratio of 1:5 to a mixed solvent composed of ethanol and water in a volume ratio of 3:2 (the ratio of the mixed solvent to the solute in it is 10mL:1g), carry out the ring-opening reaction at 80°C for 6h, and then add excess acetone to terminate the ring-opening reaction;

(3) Add dropwise a 10% sodium hydroxide solution with a molar ratio of 5:1 to the above-mentioned benzimidazole intermediate into the material obtained in step (2), carry out ring-closing reaction at 80°C for 6h, and separate and remove The brine is washed thoroughly with deionized water, and then the water is removed with anhydrous manganese sulfate, and then the solvent is removed by rotary evaporation under reduced pressure to obtain the monomer of the hydrogen nuclear magnetic spectrum as shown in Figure 2. Its structural formula is:

(4) Curing the obtained monomer at 120°C for 2h and post-curing at 180°C for 2h to obtain the biomass intrinsic flame-retardant and high-temperature resistant epoxy resin.

The biomass intrinsic flame-retardant and high-temperature resistant epoxy resin prepared in this example and the resin obtained after curing of bisphenol A epoxy resin with diaminodiphenylmethane were analyzed and compared by thermogravimetric curve under nitrogen atmosphere, and the results are as follows Shown in Figure 3.

Example 2

(1) Add phthalamide and ethyl vanillin to N,N-dimethylformamide at a molar ratio of 1:1, and then add sodium metabisulfite equimolar to phthalamide to the reactor The ratio of N,N-dimethylformamide to the solute in it is 10mL:1g, stirred at 130℃ for 6h, precipitated with excess ice water, filtered the precipitate, washed and dried under reduced pressure to obtain the benzimidazole intermediate ；

(3) Add dropwise a 10% sodium hydroxide solution with a molar ratio of 5:1 to the above-mentioned benzimidazole intermediate into the material obtained in step (2), carry out ring-closing reaction at 80°C for 6h, and separate and remove The brine is thoroughly washed with deionized water, and then the water is removed with anhydrous manganese sulfate, and then the solvent is removed by rotary evaporation under reduced pressure to obtain the biomass intrinsic flame-retardant and high-temperature resistant epoxy monomer. Its structural formula is:

Example 3

(1) Add phthalic diamine and vanillin to N,N-dimethylformamide at a molar ratio of 1:1, and then add sodium metabisulfite equimolar to phthalic acid to the reactor, N, The ratio of N-dimethylformamide to the solute therein is 10mL:1g, the reaction is stirred at 130°C for 6h, precipitated with excess ice water, the precipitate is filtered, washed and dried under reduced pressure to obtain the benzimidazole intermediate;

Example 4

(1) Add phthalic diamine and syringaldehyde to N,N-dimethylformamide at a molar ratio of 1:1, and then add sodium metabisulfite equimolar to phthalic acid to the reactor, N, The ratio of N-dimethylformamide to the solute therein is 10mL:1g, the reaction is stirred at 130°C for 6h, precipitated with excess ice water, the precipitate is filtered, washed and dried under reduced pressure to obtain the benzimidazole intermediate;

Example 5

(1) Add phthalic diamine and p-hydroxybenzaldehyde to N,N-dimethylformamide at a molar ratio of 1:1, and then add sodium metabisulfite equimolar to phthalic acid to the reactor, The ratio of N,N-dimethylformamide to the solute therein is 10mL:1g, stirred at 130°C for 6h, precipitated with excess ice water, filtered the precipitate, washed and dried under reduced pressure to obtain the benzimidazole intermediate;

The above are only the preferred embodiments of the present invention, so the scope of implementation of the present invention cannot be limited accordingly. That is, equivalent changes and modifications made according to the scope of the patent of the present invention and the contents of the specification should still be covered by the present invention. In the range.

Industrial applicability

The invention discloses a biomass intrinsic flame-retardant and high-temperature resistant epoxy resin and a preparation method thereof. The structural formula of the monomer is

The present invention introduces a benzimidazole-like structure, which has high-efficiency solid-phase flame retardant effect, can promote the formation of carbon layer and improve the flame-retardant performance of epoxy resin; introduce the benzimidazole-like structure into the epoxy resin, The rigid structure of benzimidazole and heterocyclic nitrogen atoms can form hydrogen bonds with epoxy resin side hydroxyl groups, which will greatly improve the heat resistance of epoxy resin; no phosphorus or halogen elements are introduced, and the selected raw materials are Biomass platform product, and finally obtained epoxy resin is green and environmentally friendly, with industrial applicability.

Claims

A biomass intrinsic flame-retardant and high-temperature resistant epoxy resin, which is characterized in that the structural formula of its monomer is
Where R is
The preparation method of a biomass intrinsic flame-retardant and high-temperature resistant epoxy resin according to claim 1, characterized in that it comprises the following steps:

(1) Add o-phenylenediamine and aromatic aldehyde compounds to the organic solvent, then add sodium metabisulfite to the reactor, stir and react at 60～140℃ for 4～8h, precipitate with excess ice water, filter the precipitate, Washing and drying under reduced pressure to obtain a benzimidazole intermediate; the above aromatic aldehyde compound is o-vanillin, ethyl vanillin, vanillin, syringaldehyde or p-hydroxybenzaldehyde;

(2) The above-mentioned benzimidazole intermediate and epichlorohydrin are added to a mixed solvent composed of ethanol and water in a volume ratio of 2-4:1-3, and the ring-opening reaction is carried out at 50-100°C. 2- 8h, add excess acetone to stop the ring-opening reaction;

(3) Add sodium hydroxide solution dropwise to the material obtained in step (2), carry out the ring-closing reaction at 60-90°C for 2-8 hours, separate and remove the brine, wash with deionized water, and then use anhydrous sulfuric acid After removing water from manganese, the solvent is removed by rotary evaporation under reduced pressure to obtain the monomer;

(4) The above monomers are cured at 110-125°C for 1.5-2.5 hours, and post-cured at 175-185°C for 1.5-2.5 hours to obtain the biomass intrinsic flame-retardant and high-temperature resistant epoxy resin.
The preparation method according to claim 2, wherein the organic solvent is at least one of ethanol, N,N-dimethylformamide, acetonitrile and methanol.
The preparation method according to claim 2 or 3, wherein the ratio of the organic solvent to the solute in the step (1) is 9-11 mL:1g.
The preparation method according to claim 2, wherein the ratio of the mixed solvent to the solute in the mixed solvent in the step (2) is 9-11 mL:1g.
The preparation method according to any one of claims 2 to 5, characterized in that: in the step (1), the molar ratio of o-phenylenediamine to aromatic aldehyde compound is 1:1-2.
The preparation method according to any one of claims 2 to 5, characterized in that: in the step (1), the sodium metabisulfite and o-phenylenediamine are equimolar.
The preparation method according to any one of claims 2 to 5, wherein in the step (2), the molar ratio of the benzimidazole intermediate to the epichlorohydrin is 1:5-10.
The preparation method according to any one of claims 2 to 5, wherein in the step (3), the molar ratio of the sodium hydroxide to the benzimidazole intermediate is 5-10:1.
9. The preparation method of claim 9, wherein the concentration of the sodium hydroxide solution is 8-11%.