CN109678880B - A kind of trifunctional benzoxazine monomer based on resveratrol and preparation method thereof - Google Patents

Abstract

The invention belongs to the technical field of thermosetting resin, and provides a trifunctional benzoxazine monomer based on resveratrol and a preparation method thereof, wherein the preparation method comprises the following steps: mixing resveratrol, amine compounds and paraformaldehyde, adding a low-polarity solvent as a reaction solvent, reacting at 80-130 ℃ for 2-6 hours, filtering after the reaction, washing the filtrate with water, and then carrying out rotary evaporation and drying to obtain the product. The invention has the advantages that the bio-based phenol is used, the synthetic target product is the trifunctional benzoxazine monomer, the synthetic steps are simple, the yield is high, the cured benzoxazine resin has excellent thermal and mechanical properties, the flame retardance is excellent, the synthetic process is simple, the requirement on equipment is low, and the invention is suitable for large-scale production.

Description

A kind of trifunctional benzoxazine monomer based on resveratrol and preparation method thereof

technical field

The invention belongs to the technical field of thermosetting resins, in particular to a bio-based resveratrol-based trifunctional benzoxazine monomer and a preparation method thereof.

Background technique

Benzoxazine polymers are a class of thermosetting polymers developed in recent years, which have attracted attention due to their obvious advantages over traditional thermosetting resins. Benzoxazine resins have excellent heat resistance, good mechanical properties, close to zero polymerization shrinkage, very flexible molecular design, high coke yield, and low surface energy. After complete curing, the glass transition temperature is high, and it has good heat resistance; benzoxazine has a similar structure to phenolic resin after ring-opening polymerization, which makes its electrical insulation performance good; At a certain temperature, the oxazine resin can be cured without any catalyst. Benzoxazine is widely used in some molding processes such as mold pressing, lamination and resin transfer modeling; as well as burn-resistant and corrosion-resistant materials, electronic packaging, mechanical manufacturing parts, aerospace materials, adhesives, circuit boards, Vacuum pump rotary vane, insulating materials and other related production fields.

With the development of society, people have higher and higher requirements for high-performance materials, which is also the research direction of many researchers and entrepreneurs. Secondly, the phenolic compounds for synthesizing benzoxazine resins are mainly derived from petroleum, and their decomposition products have some environmental hazards. In terms of available petrochemical raw materials and costs, benzoxazine resins are faced with the commercialization of many other Same challenges for polymers. At the same time, the extensive use of petrochemical-based polymer materials will release potentially toxic waste, resulting in subsequent environmental pollution. The use of bio-based raw materials can solve this problem well and is in line with the concept of green chemistry. The benzoxazine prepared by the patent number (CN108250382A) uses the bio-based material bisphenolic acid, but its heat resistance is not good enough, and the residual carbon rate only reaches 50%. Patent No. (CN107459512A), the reaction time for synthesizing biological benzoxazine is too long, it needs to consume a lot of thermal energy, and the thermal performance is not excellent enough.

SUMMARY OF THE INVENTION

In view of some deficiencies existing in bio-based resins, the present invention uses bio-based resveratrol as a phenol source in the molecular design of benzoxazine monomers to synthesize novel trifunctional benzoxazine monomers, and the cured benzene The oxazine resin material has excellent heat resistance and flame retardancy. When the inert gas atmosphere is 800 ℃, the residual carbon rate is as high as 65-80%, and the combustion heat release energy is 30-100Jg ^-1 K ^-1 . The obtained resin material has very excellent thermal and mechanical properties; the synthesis process is simple, the yield is high, the equipment requirements are low, and it is suitable for large-scale production.

The object of the present invention is to improve the cross-linking degree of benzoxazine resin by preparing trifunctional benzoxazine, thereby improving its heat resistance and flame retardancy, and providing a kind of bio-based resveratrol as phenol source. Trifunctional benzoxazine and preparation method thereof.

The purpose of this invention is to realize through the following technical solutions:

One of the objects of the present invention is to provide a kind of trifunctional benzoxazine monomer based on resveratrol, and its molecular chemical structural formula is as follows:

为以下结构之一：in,

is one of the following structures:

The second object of the present invention is to provide a kind of preparation method of the trifunctional benzoxazine monomer based on resveratrol, specifically comprises the steps:

Add resveratrol, amine compounds, and paraformaldehyde into the flask, add a low-polarity solvent, react at 80-130 ° C for 2-6 hours, stop the reaction, filter the reactant, and wash the filtrate with water 1-3 times After rotary steaming and drying, a solid product is obtained, which is a trifunctional benzoxazine monomer based on resveratrol.

The reaction equation is:

The structural formula of the amine compound is R-NH ₂ , which is one of the following structures:

The molar ratio of the resveratrol, the amine compound, and the paraformaldehyde is 1:3:6-1:3:9.

The optimal molar ratio of resveratrol, amine compound and paraformaldehyde is 1:3:6.6.

The low-polarity solvent is one or several mixtures of toluene, xylene and dioxane.

The trifunctional benzoxazine monomer based on cucurbitol prepared by the present invention is further cured and cross-linked to obtain a polybenzoxazine resin, and the temperature of the polybenzoxazine resin is 350-350-5% when the thermal weight loss is 5% under the protection of nitrogen. At 450℃ and 800℃, the residual carbon rate is 60-80%. The combustion heat release energy is 30-100Jg ^-1 K ^-1 .

Compared with the prior art, the advantages of the present invention are:

Using bio-based resveratrol as the phenol source, the raw material reduces the pollution to the environment, and the trifunctional benzoxazine is synthesized, which has excellent heat resistance and resistance compared with the traditional monofunctional or bifunctional benzoxazine. Flammability, when the inert gas atmosphere is 800 ℃, the residual carbon rate is 65-80%, and the combustion heat release energy is 30-100Jg ^-1 K ^-1 . The obtained resin material has very excellent thermal and mechanical properties; the synthesis process is simple, the yield is high, the equipment requirements are low, and it is suitable for large-scale production.

Description of drawings

The hydrogen nuclear magnetic resonance spectrogram of the benzoxazine resin that Fig. 1 embodiment 1 obtains;

The infrared spectrogram of the benzoxazine resin that Fig. 2 embodiment 1 obtains;

The DSC spectrogram of the benzoxazine resin that Fig. 3 embodiment 1 obtains;

Fig. 4 TGA spectrum of the cured benzoxazine resin obtained in Example 1.

Detailed ways

Specific embodiments of a resveratrol-based trifunctional benzoxazine monomer and a preparation method thereof of the present invention are provided below. It is necessary to point out that the following examples are only used to describe the present invention in more detail, rather than to narrow the protection scope of the present invention. Improvements and adjustments made by those skilled in the art after reading the present invention without departing from the concept of the present invention are all within the scope of protection of the present invention.

Example 1

2-Furanmethylamine was used as the amine source.

Add 1 g (0.0044 mol) of resveratrol, 1.276 (0.0132 mol) of 2-furan methylamine, 0.868 g (0.0289 mol) of paraformaldehyde to the flask, add 50 ml of toluene solution, connect a condenser tube, and stir at 110°C And react for 4h. The filtrate after the reaction was rotary-evaporated to remove the solvent to obtain 1.8 g of benzoxazine monomer with a yield of 68%. The chemical reaction equation is as follows:

In the present embodiment, the oxazine product structure obtained is:

The proton nuclear magnetic resonance spectrum, Fourier infrared transform spectrum, DSC curve and thermogravimetric curve of the product are shown in Figure 1, Figure 2, Figure 3 and Figure 4.

Accompanying drawing 1 hydrogen nuclear magnetic resonance spectrum. The chemical shifts around 4.8ppm and 3.9ppm are characteristic peaks of methylene on the oxazine ring. Figure 2 is an infrared spectrogram, wherein 920 and 1227 cm ^-1 are characteristic absorption peaks of the benzoxazine ring. Figure 3 is a DSC curve diagram, the curing exothermic peak temperature of the benzoxazine monomer is 229°C. Figure 4 is a TGA curve diagram of the cured resin material. It can be seen that the temperature of the benzoxazine resin when the thermal weight loss is 10% is 354°C, and the carbon residue rate at 800°C is 68%. In addition, the heat release energy of the benzoxazine resin obtained in this example after curing is 55Jg ^-1 K ^-1 as a result of the flame retardant test.

Example 2

The amine source compound 2-furanmethylamine in Example 1 was replaced with aniline. Other steps are the same as those in Example 1.

反应物的量改为：称取白藜芦醇1.14g(0.005mol)，苯胺1.40g(0.015mol)，多聚甲醛0.99g(0.033mol)，收率79％。The specific chemical structural formula of aniline is:

The amounts of the reactants were changed to: 1.14 g (0.005 mol) of resveratrol, 1.40 g (0.015 mol) of aniline, 0.99 g (0.033 mol) of paraformaldehyde were weighed, and the yield was 79%.

The curing exothermic peak temperature of the trifunctional benzoxazine monomer obtained in this example is 230° C. After further curing and crosslinking, the temperature of the polybenzoxazine resin when the thermal weight loss is 5% is 353° C., and the inert gas atmosphere is 800° C. , the residual carbon rate was 61%, and the heat release energy of the flame retardant test results was 79Jg ^-1 K ^-1 .

Example 3

The amine source compound 2-furanmethylamine in Example 1 was replaced with 4-chloroaniline. Other steps are the same as those in Example 1.

反应物的量改为：称取白藜芦醇1.14g(0.005mol)，4-氯苯胺1.91g(0.015mol)，多聚甲醛0.99g(0.033mol)，收率75％。Wherein the specific chemical structural formula of 4-chloroaniline is:

The amount of the reactant was changed to: 1.14 g (0.005 mol) of resveratrol, 1.91 g (0.015 mol) of 4-chloroaniline, 0.99 g (0.033 mol) of paraformaldehyde were weighed, and the yield was 75%.

The benzoxazine curing exothermic peak temperature obtained in this example is 233°C. After further curing and crosslinking, the polybenzoxazine resin has a temperature of 357°C when the thermal weight loss is 5%, and when the inert gas atmosphere is 800°C, the residual carbon The rate is 62%, and the heat release energy of the flame retardant test results is 73Jg ^-1 K ^-1 .

Example 4

The amine source compound 2-furanmethylamine in Example 1 was replaced with m-alkynylaniline. Other steps are the same as those in Example 1.

反应物的量改为：称取白藜芦醇1.14g(0.005mol)，间炔苯胺1.76g(0.015mol)，多聚甲醛0.99g(0.033mol)。收率82％。The specific chemical structural formula of m-alkynyl aniline is:

The amounts of the reactants were changed to: 1.14 g (0.005 mol) of resveratrol, 1.76 g (0.015 mol) of m-alkynyl aniline, and 0.99 g (0.033 mol) of paraformaldehyde were weighed. Yield 82%.

The curing exothermic peak temperature of the benzoxazine monomer obtained in this example is 189°C. After further curing and crosslinking, the polybenzoxazine resin has a temperature of 420°C when the thermal weight loss is 5%, and when the inert gas atmosphere is 800°C, The residual carbon rate was 75%, and the heat release energy of the flame retardant test results was 30Jg ^-1 K ^-1 .

Claims (6)

1. A trifunctional benzoxazine monomer based on resveratrol is characterized in that the molecular formula is as follows:

wherein,

is one of the following structures:

2. the resveratrol-based trifunctional benzoxazine monomer according to claim 1, wherein the trifunctional benzoxazine monomer based on cucurbitol is further cured and crosslinked to obtain polybenzoxazine resin, the polybenzoxazine resin has a thermal weight loss of 5% under nitrogen protection, a temperature of 350-450 ℃, a carbon residue rate of 60-80% at 800 ℃, and a combustion heat release energy of 30-100Jg^-1K^-1。

3. The method for preparing the resveratrol-based trifunctional benzoxazine monomer according to claim 1, specifically comprising the following steps:

adding resveratrol, amine compounds and paraformaldehyde into a flask, adding a low-polarity solvent, reacting at 80-130 ℃ for 2-6 hours, filtering the reactant after the reaction is stopped, and carrying out rotary evaporation on the filtrate after water is used, and drying to obtain a solid product, namely a trifunctional benzoxazine monomer based on resveratrol;

the low-polarity solvent is one or a mixture of toluene, xylene and dioxane.

4. White-based according to claim 3The preparation method of the tri-functional benzoxazine monomer of veratryl alcohol is characterized in that the structural formula of the amine compound is R-NH₂Is one of the following structures:

5. the method for preparing the tri-functional benzoxazine monomer based on resveratrol according to claim 3, wherein the molar ratio of the resveratrol to the amine compound to the paraformaldehyde is 1: 3: 6-1: 3: 9.

6. the method for preparing a trifunctional benzoxazine monomer based on resveratrol according to claim 5, wherein the optimal molar ratio of resveratrol, amine compound and paraformaldehyde is 1: 3: 6.6.

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