CN109678880B

CN109678880B - Tri-functional benzoxazine monomer based on resveratrol and preparation method thereof

Info

Publication number: CN109678880B
Application number: CN201910016163.1A
Authority: CN
Inventors: 张侃; 韩梦超; 刘宇奇
Original assignee: Jiangsu University
Current assignee: CHENGDU KEYI POLYMER TECHNOLOGY Co.,Ltd.
Priority date: 2019-01-08
Filing date: 2019-01-08
Publication date: 2021-05-25
Anticipated expiration: 2039-01-08
Also published as: CN109678880A

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

Tri-functional benzoxazine monomer based on resveratrol and preparation method thereof

Technical Field

The invention belongs to the technical field of thermosetting resin, and particularly relates to a trifunctional benzoxazine monomer based on bio-based resveratrol and a preparation method thereof.

Background

Benzoxazine polymers are a class of thermoset polymers developed in recent years and have received attention because of their significant advantages over traditional thermoset resins. The benzoxazine resin has excellent heat resistance, good mechanical property, polymerization shrinkage close to zero, very flexible molecular design, high coke yield, lower surface energy and other excellent characteristics. After the curing is completely carried out, the glass transition temperature is high, and the heat resistance is good; after ring-opening polymerization, benzoxazine has a structure similar to that of phenolic resin, so that the benzoxazine has good electrical insulation performance; the benzoxazine resin can be cured without any catalyst at a certain temperature. Benzoxazine is widely used in some molding processes such as mold pressing, lamination, resin transfer molding, and the like; and the related production fields of burning-resistant and corrosion-resistant materials, electronic packaging, parts in the mechanical manufacturing industry, aerospace materials, adhesives, circuit boards, vacuum pump rotary sheets, insulating materials and the like.

With the development of society, people have higher and higher requirements on high-performance materials, which is also the research direction of many researchers and entrepreneurs. Secondly, the phenolic compounds that synthesize benzoxazine resins are mainly derived from petroleum, and their decomposition products are somewhat harmful to the environment, and benzoxazine resins face the same challenges as many other commercial polymers in terms of available petrochemical raw materials and costs. Meanwhile, a great amount of polymer materials based on petrochemical products release potential toxic wastes, subsequent environmental pollution is caused, the problem can be well solved by using bio-based raw materials, and the concept of green chemistry is met. The benzoxazine prepared by the patent number (CN108250382A) uses bio-based material diphenolic acid, but the heat resistance is not excellent enough, and the carbon residue rate only reaches 50%. The reaction time of the synthetic biological benzoxazine of the patent number (CN107459512A) is too long, much heat energy is consumed, and the thermal property is not excellent enough.

Disclosure of Invention

In view of some defects of the existing bio-based resin, the invention takes bio-based resveratrol as a phenol source in the molecular design of benzoxazine monomer to synthesize novel trifunctional benzoxazine monomer, the cured benzoxazine resin material has excellent heat resistance and flame retardance, the carbon residue rate is as high as 65-80% at 800 ℃ in an inert gas atmosphere, and the heat release energy during combustion is 30-100Jg^-1K^-1. The obtained resin material has excellent thermal and mechanical properties; the synthesis process is simple, the yield is high, the requirement on equipment is low, and the method is suitable for large-scale production.

The invention aims to improve the crosslinking degree of benzoxazine resin by preparing trifunctional benzoxazine, thereby improving the heat resistance and the flame retardance of the benzoxazine resin, and provides the trifunctional benzoxazine taking bio-based resveratrol as a phenol source and a preparation method thereof.

The purpose of the invention is realized by the following technical scheme:

one of the purposes of the invention is to provide a trifunctional benzoxazine monomer based on resveratrol, the molecular chemical structural formula of which is shown as follows:

wherein the content of the first and second substances,

is one of the following structures:

the invention also aims to provide a preparation method of a trifunctional benzoxazine monomer based on resveratrol, which comprises the following steps:

adding resveratrol, an amine compound 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, washing the filtrate with water for 1-3 times, then carrying out rotary evaporation, and drying to obtain a solid product, namely the trifunctional benzoxazine monomer based on resveratrol.

The reaction equation is:

the structural formula of the amine compound is R-NH₂Is one of the following structures:

the resveratrol, the amine compound and the paraformaldehyde are mixed according to a molar ratio of 1: 3: 6-1: 3: 9.

the optimal molar ratio of the resveratrol to the amine compound to the paraformaldehyde is 1: 3: 6.6.

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

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

Compared with the prior art, the invention has the advantages that:

the bio-based resveratrol is used as a phenol source, so that the pollution to the environment is reduced from the raw material, and the trifunctional benzene is synthesizedCompared with the traditional monofunctional or bifunctional benzoxazine, the benzoxazine has excellent heat resistance and flame retardance, the carbon residue rate is 65-80% at the temperature of 800 ℃ in the inert gas atmosphere, and the heat release energy during combustion is 30-100Jg^-1K^-1. The obtained resin material has excellent thermal and mechanical properties; the synthesis process is simple, the yield is high, the requirement on equipment is low, and the method is suitable for large-scale production.

Drawings

FIG. 1 nuclear magnetic resonance hydrogen spectrum of benzoxazine resin obtained in example 1;

FIG. 2 is an infrared spectrum of the benzoxazine resin obtained in example 1;

FIG. 3 DSC spectrum of benzoxazine resin obtained in example 1;

FIG. 4 TGA spectrum of cured benzoxazine resin obtained in example 1.

Detailed Description

The following provides a specific embodiment of a trifunctional benzoxazine monomer based on resveratrol and a preparation method thereof. It is to be noted that: the following examples are intended only to illustrate the present invention in more detail, and do not narrow the scope of the present invention. Modifications and adaptations of the present invention may occur to those skilled in the art after reading the present invention and may be made without departing from the spirit and scope of the present invention as defined by the appended claims.

Example 1

2-furanmethanamine is used as an amine source.

1g (0.0044mol) of resveratrol, 1.276(0.0132mol) of 2-furanmethanamine and 0.868g (0.0289mol) of paraformaldehyde were put into a flask, 50ml of a toluene solution was added, a condenser tube was connected, and stirring and reaction were carried out at 110 ℃ for 4 hours. And (3) removing the solvent from the reacted filtrate by rotary evaporation to obtain 1.8g of benzoxazine monomer with the yield of 68%. The chemical reaction equation is as follows:

in this example, the structure of the obtained oxazine product is:

the nuclear magnetic resonance hydrogen spectrogram, Fourier infrared transform spectrogram, DSC curve chart and thermogravimetry curve chart of the product are shown in figure 1, figure 2, figure 3 and figure 4.

FIG. 1 shows a NMR chart. Chemical shifts of about 4.8ppm and 3.9ppm are characteristic peaks of methylene on the oxazine ring. FIG. 2 is an infrared spectrum of 920 and 1227cm^-1The position is a characteristic absorption peak of the benzoxazine ring. FIG. 3 is a DSC graph showing the peak temperature of the benzoxazine monomer curing exotherm at 229 ℃. FIG. 4 is a TGA graph of the cured resin material, and it can be seen that the temperature of the benzoxazine resin is 354% when the thermal weight loss is 10%, and the carbon residue rate is 68% at 800 ℃. In addition, the benzoxazine resin obtained in the example had a heat release energy of 55Jg as a result of a flame retardancy test after curing^-1K^-1。

Example 2

The amine source compound 2-furanmethanamine in example 1 was replaced with aniline. The other steps were the same as in example 1.

Wherein the specific chemical structural formula of the aniline is as follows:

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

The curing exothermic peak temperature of the trifunctional benzoxazine monomer obtained in the embodiment is 230 ℃, after further curing and crosslinking, the polybenzoxazine resin has 353 ℃ of temperature when the thermal weight loss is 5%, 61% of carbon residue rate when the temperature is 800 ℃ in an inert gas atmosphere, and 79Jg of heat release energy according to a flame retardant test result^-1K^-1。

Example 3

The amine source compound 2-furanmethanamine in example 1 was replaced with 4-chloroaniline. The other steps were the same as in example 1.

Wherein the specific chemical structural formula of the 4-chloroaniline is as follows:

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

The peak temperature of the heat release of the benzoxazine obtained in the embodiment is 233 ℃, after further curing and crosslinking, the temperature of the polybenzoxazine resin is 357 ℃ when the thermal weight loss is 5%, the carbon residue rate is 62% when the polybenzoxazine resin is in an inert gas atmosphere of 800 ℃, and the heat release energy of the flame retardant test result is 73Jg^-1K^-1。

Example 4

The amine source compound 2-furanmethanamine in example 1 was replaced with m-alkynylaniline. The other steps were the same as in example 1.

The specific chemical structural formula of the intermediate alkynylaniline is as follows:

the amounts of reactants were changed to: 1.14g (0.005mol) of resveratrol, 1.76g (0.015mol) of m-alkynylaniline and 0.99g (0.033mol) of paraformaldehyde are weighed. The yield thereof was found to be 82%.

The curing exothermic peak temperature of the benzoxazine monomer obtained in the embodiment is 189 ℃, after further curing and crosslinking, the polybenzoxazine resin has a temperature of 420% when the thermal weight loss is 5%, a carbon residue rate of 75% when the temperature is 800 ℃ in an inert gas atmosphere, and a heat release energy of 30Jg according to a flame retardant test result^-1K^-1。

Claims

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

wherein the content of the first and second substances,

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.