CN109776518B

CN109776518B - Novel AB type benzoxazine monomer and preparation method thereof

Info

Publication number: CN109776518B
Application number: CN201910039109.9A
Authority: CN
Inventors: 张侃; 刘宇奇; 韩梦超; 王雨亭; 胡杰
Original assignee: Jiangsu University
Current assignee: CHENGDU KEYI POLYMER TECHNOLOGY Co.,Ltd.
Priority date: 2019-01-16
Filing date: 2019-01-16
Publication date: 2021-05-25
Anticipated expiration: 2039-01-16
Also published as: CN109776518A

Abstract

The invention belongs to the technical field of high-performance thermosetting resin, and discloses a novel AB type benzoxazine monomer and a preparation method thereof. Synthesizing 4-maleimide phenol by maleic anhydride and p-aminophenol; and synthesizing a benzoxazine monomer by using 4-maleimide phenol, 2-furanmethanamine and paraformaldehyde as raw materials. The maleimide and furan groups in the AB type benzoxazine monomer can generate Diels-Alder reaction after the AB type benzoxazine monomer is melted to generate main chain type benzoxazine, and the resin material is formed through heating and curing, and the unique mechanism enables the resin to have good thermal property. The residual carbon rate of the material after monomer curing at 800 ℃ is 57 percent, and T_d5At 357 ℃ and T_d10The temperature was 401 ℃. The material obtained by the AB type benzoxazine monomer has excellent thermal and mechanical properties, good processability and low production cost, and is suitable for large-scale production.

Description

Novel AB type benzoxazine monomer and preparation method thereof

Technical Field

The invention belongs to the technical field of high-performance thermosetting resin, and particularly relates to a preparation method of a novel AB type benzoxazine monomer containing maleimide groups and furan groups.

Background

Benzoxazine is a new type of thermosetting resin which can be polymerized by a ring-opening reaction, and the benzoxazine resin exhibits many specific properties such as zero volume shrinkage during heat curing, no by-product generation, low water absorption, excellent dielectric properties, good thermal stability, and the like. It has therefore attracted increasing attention from researchers and industries. Furthermore, benzoxazines also have a very flexible molecular design.

Maleimide-functionalized benzoxazine resin is a high performance resin, and patent No. (CN101235033A) discloses a maleimide and allyl ether benzoxazine, which has good heat resistance, but the resin is a monofunctional monomer, and the material is brittle and is not easy to process into a film. The benzoxazine can be used as a matrix to be blended with other resins, so as to achieve the purpose of improving certain properties. For example, the ring-opening polymerized phenolic resin and fiber reinforced composite material disclosed in patent No. (CN94111852) has good preparation and molding processability, excellent physical and mechanical properties, and is suitable for being used as a high-temperature resistant structural material and an electrical insulating material for a long time, but the thermal properties of the composite material need to be further improved. The maleimide internal chain extension modified benzoxazine resin disclosed in the patent number (CN108359069A) has the same and insufficient excellent thermal property. Due to the development of modern science and technology, people have higher and higher requirements on high-performance materials, and the performance of benzoxazine needs to be further improved so as to meet the application of benzoxazine in various fields, such as improving the heat resistance of benzoxazine to meet the use requirements of benzoxazine in certain high-temperature environments.

Disclosure of Invention

The invention mainly aims to overcome the defects of the prior art and provide a preparation method of a novel AB type benzoxazine monomer. The purpose of the invention and the technical problem to be solved are realized by adopting the following technical scheme. The novel AB type benzoxazine monomer provided by the invention has the following molecular structural formula:

the AB type benzoxazine monomer has the curing peak temperature of 213.85 ℃, the carbon residue rate of the cured resin material at 800 ℃ of 57 percent and T_d5At 357 ℃ and T_d10The temperature was 401 ℃.

The preparation method of the novel AB type benzoxazine monomer comprises the following steps:

(1) synthesis of 4-maleimidophenol

Mixing maleic anhydride and p-aminophenol in proportion, adding a catalyst, taking DMF as a solvent, reacting for 1h in an ice bath, then reacting for 3h at 70 ℃, pouring a reaction solution into a large amount of water, filtering a precipitated solid by suction, and drying to obtain the 4-maleimide phenol. The reaction equation is as follows:

in the step (1), the molar ratio of the maleic anhydride to the p-aminophenol is 1.1: 1.

in the step (1), the catalyst is concentrated sulfuric acid and phosphorus pentoxide, the mass of the phosphorus pentoxide accounts for 20-40% of the total mass of the p-aminophenol and the maleic anhydride, and the concentrated sulfuric acid accounts for 10-20% of the total mass of the aminophenol and the maleic anhydride.

(2) Synthesis of benzoxazine monomers

Mixing the 4-maleimide phenol prepared in the step (1), 2-furanmethanamine and paraformaldehyde, adding into a flask, adding a low-polarity solvent, stirring and reacting in an oil bath kettle, slowly heating the temperature from room temperature to 100 ℃ and reacting for 4-6h, purifying substances in a reaction solution, and drying in a 50 ℃ vacuum drying oven for 24h to obtain the AB type benzoxazine monomer.

The reaction equation is as follows:

in the step (2), the low-polarity solvent is one or more of toluene, xylene or 1, 4-dioxane.

In the step (2), the molar ratio of the 4-maleimide phenol to the 2-furanmethanamine to the paraformaldehyde is 1:1: 2-1: 1: 2.4, preferably in a ratio of 1:1: 2.2.

The novel AB type benzoxazine monomer prepared by the invention is used as matrix resin to be applied to the fields of fiber reinforced materials, brake pads and aerospace.

The invention has the beneficial effects that:

(1) aiming at the brittleness defect of benzoxazine monomer resin, through the design of an AB type monomer, a reactive maleimide group and a furan group are simultaneously introduced into benzoxazine, before solidification, the reactive maleimide group and the furan group are subjected to intermolecular Diels-Alder reaction through melting, linear high molecules with high molecular weight are firstly formed, and then the crosslinked resin material is obtained through thermal solidification, so that the performance of the benzoxazine is improved to a certain extent.

(2) The resin monomer prepared by the invention is proved by methods such as nuclear magnetic resonance, infrared, differential scanning calorimetry, comprehensive thermal analysis and the like, and the novel AB type benzoxazine monomer synthesized by the method has the carbon residue rate of 57 percent at 800 ℃ and the T percent at the temperature of 800 ℃ after being cured_d5At 357 ℃ and T_d10The temperature was 401 ℃.

Drawings

FIG. 1 is an infrared spectrum of an AB type benzoxazine monomer obtained in example 1;

FIG. 2 nuclear magnetic resonance hydrogen spectrum of AB type benzoxazine monomer obtained in example 1;

FIG. 3 nuclear magnetic resonance carbon spectrum of AB type benzoxazine monomer obtained in example 1;

FIG. 4 DSC spectrum of AB type benzoxazine monomer obtained in example 1;

FIG. 5 TGA spectrum of cured AB type benzoxazine monomer obtained in example 1.

Detailed Description

To further illustrate the technical means and effects of the present invention adopted to achieve the predetermined objects, the present invention provides a novel AB-type benzoxazine monomer and its preparation method, and the specific embodiments and features thereof. As will be described in detail below.

The first embodiment is as follows:

the first step is as follows: 5g of maleic anhydride and 5.102g of p-aminophenol are mixed, 1.5g of concentrated sulfuric acid and 3g of phosphorus pentoxide are added, 30ml of DMF is added, the mixture is aged for 1 hour in an ice bath, then the mixture reacts for 3 hours at the temperature of 70 ℃, reaction liquid is poured into a large amount of water, and precipitated solid is filtered by suction and dried to obtain 7g of 4-maleimide phenol.

The second step is that: adding 2g of 4-maleimide phenol obtained in the first step, 1.026g of 2-furanmethanamine and 0.679g of paraformaldehyde into a flask, adding 50ml of toluene solution, stirring and reacting in an oil bath kettle, slowly raising the temperature from room temperature to 110 ℃, reacting for 6h, purifying substances in the reaction solution, and drying in a 50 ℃ vacuum drying oven for 24h to obtain 2.156gAB type benzoxazine, wherein the yield is 72.5%.

FIG. 1 is an infrared spectrum of an AB type benzoxazine monomer, wherein 964 and 1230cm-1 are characteristic peaks of oxazine ring.

FIG. 2 is a nuclear magnetic resonance hydrogen spectrogram of an AB type benzoxazine monomer, and chemical shifts of about 4.9ppm and 4.1ppm are characteristic peaks of methylene on an oxazine ring.

FIG. 3 is a nuclear magnetic carbon spectrum of an AB type benzoxazine monomer, and characteristic peaks of methylene carbon atoms on oxazine rings are at chemical shifts of 48 and 82 ppm.

FIG. 4 is a DSC graph of AB type benzoxazine monomer with a curing exothermic peak temperature of 213.85 ℃.

FIG. 5 is a TGA graph of the resin material after the AB type benzoxazine monomer is cured, and it can be seen that the temperature of the benzoxazine resin with 10% thermal weight loss is 401 ℃, and the carbon residue rate at 800 ℃ is 57%.

Example two:

the first step is the same as in example 1.

The second step is that: adding 2g of 4-maleimide phenol, 0.770g of 2-furanmethanamine and 0.509g of paraformaldehyde into a flask, adding 50ml of xylene solution, stirring and reacting in an oil bath kettle, slowly raising the temperature from room temperature to 120 ℃, reacting for 5h, purifying substances in the reaction solution, and drying in a 50 ℃ vacuum drying oven for 24h to obtain 1.950gAB type benzoxazine, wherein the yield is 65.6%.

Example three:

the first step is the same as in example 1.

The second step is that: 1g of 4-maleimide phenol, 0.513g of 2-furanmethanamine and 0.339g of paraformaldehyde are added into a flask, 40ml of toluene solution is added, stirring and reaction are carried out in an oil bath kettle, the temperature is slowly increased to 100 ℃ from room temperature, reaction is carried out for 6h, substances in the reaction solution are purified, and drying is carried out in a 50 ℃ vacuum drying oven for 24h, so that 1.125gAB type benzoxazine is obtained, and the yield is 75.7%.

Although the present invention has been described with reference to the above embodiments, it should be understood that the present invention is not limited to the above embodiments, but rather, the present invention is capable of other modifications and variations, and it will be apparent to those skilled in the art that the invention can be practiced without departing from the spirit and scope of the appended claims.

Claims

1. A novel AB type benzoxazine monomer is characterized in that the molecular structural formula is as follows:

2. a novel AB-type benzoxazine monomer according to claim 1 wherein the curing peak temperature is 213.85 ℃, the char yield of the cured resin material at 800 ℃ is 57%, and T is_d5At 357 ℃ and T_d10The temperature was 401 ℃.

3. A method for preparing a novel AB-type benzoxazine monomer according to claim 1, comprising the steps of:

(1) synthesis of 4-Maleimidophenol:

mixing maleic anhydride and p-aminophenol in proportion, adding a catalyst, taking DMF as a solvent, reacting in ice bath, then reacting at 70 ℃, pouring a reaction solution into a large amount of water, filtering a precipitated solid by suction, and drying to obtain 4-maleimide phenol;

(2) and (3) synthesis of AB type benzoxazine monomer:

mixing the 4-maleimide phenol prepared in the step (1), 2-furanmethanamine and paraformaldehyde, adding into a flask, adding a low-polarity solvent, stirring and reacting in an oil bath kettle, slowly heating the temperature from room temperature to 100 ℃ for 120 ℃, reacting for 4-6h, purifying substances in a reaction liquid, and drying in vacuum to obtain the AB type benzoxazine monomer.

4. The method for preparing novel AB type benzoxazine monomers according to claim 3, wherein in step (1), the molar ratio of maleic anhydride and p-aminophenol is 1.1: 1; the catalyst is concentrated sulfuric acid and phosphorus pentoxide, the mass of the phosphorus pentoxide accounts for 20-40% of the total mass of the p-aminophenol and the maleic anhydride, and the mass of the concentrated sulfuric acid accounts for 10-20% of the total mass of the p-aminophenol and the maleic anhydride.

5. A method for preparing a novel AB-type benzoxazine monomer according to claim 3, wherein in step (1), the reaction time in ice bath is 1h and the reaction time at 70 ℃ is 3 h.

6. A method for preparing a novel AB-type benzoxazine monomer according to claim 3, wherein in step (2), the low-polarity solvent is one or more of toluene, xylene or 1, 4-dioxane, and the molar ratio of 4-maleimidophenol, 2-furanmethanamine and paraformaldehyde is 1:1: 2-1: 1: 2.4.

7. the method for preparing a novel AB type benzoxazine monomer according to claim 6, wherein the molar ratio of 4-maleimidophenol, 2-furanmethanamine, paraformaldehyde is 1:1: 2.2.

8. a method for preparing novel AB-type benzoxazine monomers according to claim 3, wherein in step (2), the temperature of vacuum drying is 50 ℃ for 24 hours.

9. Use of a novel AB-type benzoxazine monomer according to claim 1 as matrix resin in fiber reinforced materials, brake pads and aerospace applications.