CN115403724A - Main chain type benzoxazine resin, preparation method thereof, and bisphthalonitrile-based composite material and composite cured resin containing same - Google Patents

Abstract

The invention discloses a main chain type benzoxazine resin, a preparation method thereof, a bisphthalonitrile-based composite material containing the same and a composite cured resin, wherein the main chain type benzoxazine resin is a polymer, and the middle of a molecular chain of the main chain type benzoxazine resin contains at least one of repeating units shown in the following formula:

Description

Main chain type benzoxazine resin, preparation method thereof, bisphthalonitrile-based composite material containing main chain type benzoxazine resin and composite curing resin

Technical Field

The invention relates to the field of benzoxazine, in particular to a main chain type benzoxazine resin, a composite curing resin containing the same and a preparation method of the main chain type benzoxazine resin.

Background

With the development of modern society, people have increasingly strict requirements on materials, and both the aerospace industry, the automobile industry and the wind power industry face opportunities and challenges in the technical field of recycling and reusing composite material wastes, so that the recycling and reusing of the composite material wastes are beneficial to the sustainability and sustainable development of an industrial production process, are necessary requirements on environmental protection and resource protection, and have important social significance.

With the development of new industries such as big airplanes, new energy, rail transit and the like in China, the application field of the thermosetting resin-based composite material is continuously expanded, and the recovery problem is more and more prominent. Various research institutions at home and abroad put forward related problems, and research on the recovery problem is carried out [ the green recovery research of the composite material of the Xin-Ningbo material is advanced [ J ]. The novel chemical material, 2013 (2): 168-168 ].

At present, comprehensive treatment becomes a new direction of a composite material recycling technology, and is mainly reflected in two aspects: (1) Waste recovery and reuse are considered in design and manufacture. If the blades are made of thermoplastic composite materials, bamboo fiber reinforced composite materials are adopted for research, and bio-based adhesives are adopted for research to replace epoxy resin; research new manufacturing technology, reduce the discharge of waste in the manufacturing process, and the like. (2) Various processing technologies are integrated, and the full utilization of resources is realized. At present, the advanced treatment technology in foreign countries tends to utilize other industrial foundations, comprehensively uses the methods, fully utilizes the characteristics of wastes, simultaneously recovers energy and substances, and realizes the recovery and utilization of the wastes to the maximum extent. Such as cement kiln treatment technology [ Guojun, composite material waste recovery technology and development status [ J ] scientific and technological innovation guide, 2011 (33): 99-100 ]. The main research direction is roughly divided into two aspects: the method is a new technology for processing non-renewable thermosetting composite material waste; the second is the development of renewable and degradable new materials [ segment Shijun, segment Tanchun, zhang Rui Qing, the current situation of recycling and reusing composite materials at home and abroad [ J ] plastics industry, 2011, 39 (1): 14-18 ].

For the degradation and recovery of thermosetting resin, many experts and scholars at home and abroad have conducted relevant research, and the main methods include a physical method and a chemical method, wherein the physical method mainly adopts mechanical pulverization and recovery, and the chemical method mainly includes a pyrolysis method and a solvent method [ Xuping, mu Li Juan, li Xiao, li Qian ] research progress on recovery method of thermosetting resin-based composite material [ J]Engineering plastics applications, 2013, 41 (1): 100-104.]. The Shanxi coal chemical institute Hou-Xiang forest team selectively breaks the carbon-nitrogen bond of the epoxy resin by utilizing the coordination unsaturated zinc ions, so that the high-efficiency degradation and cyclic utilization of the carbon fiber reinforced epoxy resin are realized; the degradation and recovery of glass fiber reinforced unsaturated polyester resin [ Deng T S, liu Y, cui X J, et al, cleavage of C-N bonds in carbon fiber/epoxy resin ] are realized by utilizing weakly coordinated aluminum ions to selectively break ester bondsosites.Green Chemistry,2015,17,2141-2145.]. T, iwaya, etc. in a solvent of diethylene glycol monomethyl ether and phenethyl alcohol, in K ₃ PO ₄ Under the catalysis of (3), the reaction lasts for 1-8 h at 190-350 ℃, the unsaturated polyester can be degraded, and long glass fiber is obtained by recycling and polymerization by solvent catalysis in Iwaya T, et al.Recycling of fiber reinforced plastics, 2008,43 (7): 2452-2456.]。

China mainly adopts landfill and incineration to treat thermosetting composite wastes, and the landfill method occupies land resources and causes soil damage. Land waste cannot be caused by burning, but secondary pollution can be caused due to the generation of a large amount of toxic gas in burning, and potential and unknown dangers exist [ Huaxin, ningbo material composite material green recycling research advances [ J ]. Novel chemical materials, 2013 (2): 168-168.].

Therefore, the development of a decomposable thermosetting resin system is an effective way for realizing recycling of waste thermosetting resin and adhesives, coating materials and composite materials thereof, and is also one of important directions for the development of the field of thermosetting resin.

The benzoxazine resin (BZ) is a novel thermosetting resin, is a material obtained by curing, namely, the benzoxazine resin, except for having good heat resistance and flame retardance of the traditional phenolic resin, has no volatile small molecules released in the ring-opening curing process, has nearly zero thermosetting shrinkage, lower porosity and almost no internal stress and cracks, is beneficial to processing and forming of finished products and maintaining the size of the products, simultaneously has almost no free aldehyde and phenol in the benzoxazine resin, can be used as a flame retardant material of an engine room, and is widely applied to various fields of construction, transportation, aviation, spaceflight, electronics, ships, energy sources and the like [ military, domestic and foreign composite material waste recovery technology and development [ J ]. Scientific and technological innovation instruction, 2011 (33): 99-100 ].

Meanwhile, some defects of benzoxazine still exist, such as high curing temperature, which generally reaches 200 ℃; the curing time is long; the benzoxazine resin obtained after the traditional benzoxazine polymerization is brittle and has not very high mechanical property; the processing process is complicated, most benzoxazine monomers are solid, and the benzoxazine monomers are difficult to use conveniently like liquid thermosetting resin prepolymers in the processing process; the prepolymer has a low molecular weight and is difficult to process into a film. In order to overcome the above disadvantages, researchers have developed a benzoxazine with a novel structure, namely, a synthetic monomer or a copolymer thereof containing a benzoxazine ring in the main chain, which is called main chain type benzoxazine (MCBP), by using the flexible molecular design of benzoxazine. The main chain type benzoxazine monomer tends to be crosslinked to obtain excellent strength and flexibility, and the benzoxazine monomer can be dissolved in a solvent and also can be processed in a molten state, and the material after being heated and cured is still a thermosetting polymer. The main chain type benzoxazine resin has the advantages of both thermosetting resin and thermoplastic resin, has good application prospect, and can be used as electronic packaging, printed circuit boards, aviation and film materials. [ Zenzing, zenzbijun, yinwei, et al. Preparation and performance study of low dielectric main chain type benzoxazine resin [ J ] copper clad laminate information, 2016 (05): 31-36 ].

The crosslinked network structure of the benzoxazine resin after curing is insoluble and infusible, which greatly limits the application of the benzoxazine resin in the aspects of recycling and degradability. How to degrade and recycle the cured benzoxazine is a real problem. Under the guidance of national policies, the industrial recycling and reusing process of thermosetting carbon fiber composite wastes with low energy consumption and good recycling effect is developed vigorously to realize resource recycling and reusing of the composite wastes, and has important significance for building resource-saving and environment-friendly harmonious society, responding to calls of environment protection, energy conservation, emission reduction and sustainable development at home and abroad [ Liujian leaves, song Jinmei, pengyugan, and the like ] the current situation of recycling and reusing of thermosetting carbon fiber composite wastes [ J ] novel chemical materials, 2014 (8): 216-218 ].

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides a main chain type benzoxazine resin, a composite cured resin containing the same and a preparation method of the main chain type benzoxazine resin, wherein the main chain type benzoxazine resin contains a spiro acetal structure, so that the benzoxazine resin and a composite material or a cured product containing the same can be degraded under acidity or high temperature, and after separation and recovery of degradation products, the recycling of materials can be realized, thereby completing the invention.

One of the purposes of the invention is to provide a main chain type benzoxazine resin which is a polymer, wherein the molecular chain of the polymer contains at least one of the repeating units shown in the formulas (I-1) to (I-3):

in formula (I), each R is independently selected from at least one of aliphatic group and its derivatives, alicyclic group and its derivatives, aromatic group and its derivatives.

The main chain type benzoxazine resin contains an acetal structure, so that the acid sensitivity of the material can be endowed, the degradation is realized under an acidic condition, the cyclic utilization of the material is facilitated, and the environment benefit is good. Furthermore, the acetal structure adopted by the invention is a spiro acetal which is a closed six-membered ring structure and has certain rigidity, so that the benzoxazine resin is endowed with better heat resistance in a curing process, and the cured resin is endowed with heat resistance and rigidity.

In a preferred embodiment, the molecular chain of the polymer has two terminals, one terminal is represented by one of formulas (II-1) to (II-3), and the other terminal is represented by one of formulas (III-1) to (III-3):

in the formulae (II-1) to (II-3) and the formulae (III-1) to (III-3), R has the same meaning as that of R in the formulae (I-1) to (I-3).

Wherein N in formula (II-1) is connected with R in one of formulas (I-1) to (I-3), N in formula (II-2) is connected with R in one of formulas (I-1) to (I-3), and N in formula (II-3) is connected with R in one of formulas (I-1) to (I-3); r in the formula (III-1) is connected with N in one of the formulas (I-1) to (I-3), R in the formula (III-2) is connected with N in one of the formulas (I-1) to (I-3), and R in the formula (III-2) is connected with N in one of the formulas (I-1) to (I-3).

Preferably, the main chain benzoxazine resin is at least one selected from the group consisting of polymers of formulas (i-1) to (i-3):

in the formulae (i-1) to (i-3), n is 2 to 20, preferably 4 to 14, for example 2,3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20.

In a preferred embodiment, in the formulas (I-1) to (I-3), each R is independently selected from at least one of C2-C20 alkyl and derivatives thereof, C6-C20 aryl and derivatives thereof, and C6-C20 alicyclic group and derivatives thereof.

In a further preferred embodiment, in the formulae (I-1) to (I-3), each R is independently at least one selected from the group consisting of C2-C10 alkyl groups, C6-C10 aryl groups and derivatives thereof, and C6-C10 cyclohexyl groups and derivatives thereof.

For example, in formula (I), R is selected from: C2-C10 alkyl, phenyl,

The other purpose of the invention is to provide a method for preparing the main chain type benzoxazine resin according to the first purpose of the invention, which comprises the step of reacting raw materials including a bisphenol compound containing a spiro acetal structure, a diamine compound and an aldehyde compound to obtain the main chain type benzoxazine resin.

Wherein, the method can be carried out by adopting a solution method, a solvent-free method and a suspension method disclosed in the prior art, and the solution method is preferred.

In a preferred embodiment, the bisphenol compound containing a spiro acetal structure is at least one selected from the group consisting of pentaerythritol bis (p-hydroxybenzaldehyde) represented by formula (IV-1), pentaerythritol bis (m-SQ) represented by formula (IV-2), pentaerythritol bis (o-hydroxybenzaldehyde) represented by formula (IV-3), and derivatives thereof:

in a preferred embodiment, the diamine compound is at least one selected from the group consisting of an aliphatic diamine and a derivative thereof, an aromatic diamine and a derivative thereof, and an alicyclic diamine and a derivative thereof.

In a further preferred embodiment, the diamine compound is at least one selected from the group consisting of C2 to C20 aliphatic diamines and derivatives thereof, C6 to C20 aryl diamines and derivatives thereof, and C6 to C20 alicyclic diamines and derivatives thereof.

In a further preferred embodiment, the diamine compound is at least one selected from the group consisting of C2 to C10 aliphatic diamines and derivatives thereof, C6 to C10 aryl diamines and derivatives thereof, and C6 to C10 alicyclic diamines and derivatives thereof.

For example, the diamine compound is at least one selected from the group consisting of ethylenediamine, butanediamine, hexanediamine, octanediamine, decanediamine, 1, 12-diaminododecane, p-phenylenediamine, 4 '-diaminodiphenylmethane, diaminodiphenylsulfone, and 4,4' -methylenebis (2-methylcyclohexylamine).

In a preferred embodiment, the aldehyde compound is selected from paraformaldehyde and/or an aqueous formaldehyde solution, preferably paraformaldehyde.

Wherein, when the aqueous solution of formaldehyde is selected, the concentration is 37%.

In a preferred embodiment, the ratio of the bisphenol compound containing a spiro acetal structure, the diamine compound and the aldehyde compound is 1: (2-5).

In a further preferred embodiment, the molar ratio of the bisphenol compound containing a spiro acetal structure, the diamine compound and the aldehyde compound is 1 (2-3).

Wherein the molar amount of the bisphenol compound containing the spirocyclic acetal structure is calculated by the molar amount of phenolic hydroxyl groups, the molar amount of the diamine compound is calculated by the molar amount of amine groups, and the molar amount of the aldehyde compound is calculated by the molar amount of aldehyde groups.

In a preferred embodiment, the method comprises the steps of:

step 1, mixing the aldehyde compound, the bisphenol compound containing the spiro acetal structure and the diamine compound with a solvent, and stirring;

and 2, heating to react, and performing post-treatment after the reaction is finished to obtain the main chain type benzoxazine resin.

In a preferred embodiment, in step 1, the solvent is selected from one or more (e.g., one or two) of ethanol, methanol, isopropanol, butanol, isobutanol, tetrahydrofuran, dioxane, toluene, dimethylformamide, dimethylsulfoxide, and N-methylpyrrolidone.

In a further preferred embodiment, in step 1, the solvent is selected from one or more (e.g., one or two) of isopropanol, tetrahydrofuran, dioxane, toluene, dimethylformamide, dimethylsulfoxide, and N-methylpyrrolidone.

In a still further preferred embodiment, in step 1, the solvent is selected from one or more (e.g. one or two) of isopropanol, dioxane, dimethylformamide.

In a preferred embodiment, in step 2, the temperature of the reaction is between 80 and 150 ℃, preferably between 90 and 130 ℃, such as 80 ℃, 90 ℃, 100 ℃, 110 ℃, 120 ℃, 130 ℃,140 ℃ or 150 ℃.

In a further preferred embodiment, in step 2, the reaction is carried out under reflux.

In a preferred embodiment, in step 2, the reaction is carried out for 15 to 35h, preferably 20 to 30h, for example 15h, 16h, 17h, 18h, 19h, 20h, 21h, 22h, 23h, 24h, 25h, 26h, 27h, 28h, 29h, 30h, 31h, 32h, 33h, 34h or 35h.

In a preferred embodiment, in step 2, the post-treatment comprises alkaline washing, water washing and solvent removal treatment.

In a further preferred embodiment, the washing with lye is carried out to neutrality, preferably the concentration of the lye is in the range of 0.1 to 5mol/L (preferably 0.5 to 2 mol/L), for example the concentration of the lye is 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5 or 5mol/L.

The alkali solution may be at least one selected from alkaline aqueous solutions such as sodium hydroxide aqueous solution and potassium hydroxide aqueous solution.

In a further preferred embodiment, the solvent is removed by means of vacuum drying.

The third object of the present invention is to provide a main chain type benzoxazine resin obtained by the second object of the present invention.

Wherein the main chain type benzoxazine resin is subjected to ring-opening curing to obtain the cured resin.

In a preferred embodiment, the ring-opening curing is carried out at 120 to 240 ℃, preferably 140 to 240 ℃.

In a further preferred embodiment, the ring-opening curing is performed as follows: the temperature was raised from 140 ℃ to 240 ℃ in one temperature step per 20 ℃ and the reaction was carried out for 2h per temperature step.

Specifically, the temperature ranges from 140 ℃ (2 h) to 160 ℃ (2 h) to 180 ℃ (2 h) to 200 ℃ (2 h) to 220 ℃ (2 h) to 240 ℃ (2 h).

The main chain type benzoxazine resin cured product can be degraded in an acid solution, preferably, the benzoxazine resin cured product is soaked in the acid solution and reacts for 8-48 hours to realize degradation, wherein the stronger the acidity, the longer the time and the higher the chemical degradation degree of the cured product.

Preferably, the acid used in the acidic solution is selected from the group consisting of organic acids (e.g., at least one of formic acid, acetic acid, triflic acid, trichloroacetic acid) and inorganic acids (e.g., at least one of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid).

Preferably, the solvent used in the acidic solution is a common polar solvent, and is at least one selected from water, alcohol compounds, ketone compounds, ether compounds and amide compounds; more preferably, the alcoholic solvent is selected from ethanol, methanol, isopropanol, butanol, isobutanol, phenethyl alcohol, benzyl alcohol, ethylene glycol, butylene glycol, 1, 3-propylene glycol, 1, 2-propylene glycol, glycerol, ethylene glycol monomethyl ether, diethylene glycol, triethylene glycol, dipropylene glycol, furfuryl alcohol, tetrahydrofurfuryl alcohol; the ketone compound is selected from at least one of butanone and cyclohexanone; the ether compound is selected from THF, 1, 4-dioxane; the amide compound is at least one selected from DMF, DMSO, sulfolane, N-methylpyrrolidone, morpholine and N-methylmorpholine.

The fourth purpose of the invention is to provide a bisphthalonitrile-based composite material, which comprises a main chain type benzoxazine resin and a bisphthalonitrile-based compound containing a spiro acetal structure, wherein the main chain type benzoxazine resin is selected from the main chain type benzoxazine resin in the first purpose of the invention or the main chain type benzoxazine obtained by the method in the second purpose of the invention.

Among them, the bisphthalonitrile compound containing spiro acetal structure contains spiro acetal structure, and the compound can be the bisphthalonitrile compound containing spiro acetal structure disclosed in the prior art, for example, but not limited to, patent CN112010833A and literature "Ke Li, hua Yin, kun Yang, pei Dai, ling Han and Riwei xu.synthesis and properties of phthalic-basic resin synthesis chiral acetic acid.high Performance Polymers 2020", which are incorporated herein in their entirety by CN112010833A and this literature.

The curing temperature of the bis-phthalonitrile compound purely containing the spiro acetal structure is high, the maximum curing temperature is higher than 250 ℃, and even can reach 300-400 ℃, for example, the maximum curing temperature reaches 375 ℃ in an embodiment in patent CN 112010833A. However, the inventors have found through a large number of experiments that when a mixture of a bisphthalonitrile-type compound containing a spiro acetal structure and the main chain-type benzoxazine of the present invention is cured, the presence of the main chain-type benzoxazine can lower the curing temperature of the bisphthalonitrile-type compound containing a spiro acetal structure in the mixture, and particularly, the mixture can be cured at a temperature lower than 250 ℃.

In addition, the spiro acetal structure is destroyed at high temperature (for example, 250 ℃ and above), when the bis-phthalonitrile compound containing the spiro acetal structure is solidified, the highest solidification temperature is obviously higher than 250 ℃, so that the spiro acetal bond in the compound is destroyed at high temperature, and the obtained solidified product loses degradability under acidic conditions. Therefore, the cured product of the bis-phthalonitrile compound generally containing a spiro acetal structure cannot be degraded by acid.

In the invention, the inventor finds out through a large number of experiments that the curing temperature of the bisphthalonitrile compound containing the spirocyclic acetal structure is reduced by introducing the main chain type benzoxazine into the bisphthalonitrile compound containing the spirocyclic acetal structure, and particularly, the curing can be realized at the temperature lower than 250 ℃, so that the spirocyclic acetal bond in the bisphthalonitrile compound containing the spirocyclic acetal structure is not damaged, and the acidic degradability of the bisphthalonitrile compound containing the spirocyclic acetal structure is reserved.

In a preferred embodiment, the benzoxazine accounts for 10-90 wt% and the bisphthalonitrile compound containing the spiro acetal structure accounts for 10-90 wt% of the total weight of the bisphthalonitrile-based composite material 100 wt%.

In a further preferred embodiment, the proportion of the main chain benzoxazine is 10-50 wt%, and the proportion of the bisphthalonitrile compound containing a spiro acetal structure is 50-90 wt%, based on 100wt% of the total weight of the bisphthalonitrile-based composite material.

For example, the main chain type benzoxazine accounts for 10, 20, 30, 40 or 50wt% and the bisphthalonitrile series compound containing spiro acetal structure accounts for 50, 60, 70, 80 or 90wt% based on 100wt% of the total weight of the bisphthalonitrile series composite material.

The fifth purpose of the invention is to provide a bisphthalonitrile-based composite curing resin which is a ring-opening curing product of the bisphthalonitrile-based composite material.

In a preferred embodiment, the ring-opening curing is carried out at 120 to 240 ℃; preferably, the temperature is increased from 120 ℃ to 240 ℃, each temperature gradient is 10-30 ℃, and each temperature gradient is reacted for 1-3 hours.

For example, the temperature is increased from 120 ℃ to 240 ℃, each temperature gradient is formed at 20 ℃, and each temperature gradient is reacted for 2 hours to obtain a solidified product.

Wherein the bisphthalonitrile-based composite curing resin can be degraded under an acidic condition.

Description about the incapability of degrading the phthalonitrile compound curing resin containing a spiro acetal structure: reference may be made to the document "Ke Li, hua Yin, kun Yang, pei Dai, ling Han and Riwei xu, synthesis and properties of phthalic-based resins stabilizing spiro acetic acid, high Performance Polymers 2020", where it is well established that phthalonitrile based cured resins containing a spiro acetal structure alone lose degradability, since some reaction of the spiro acetal structure may occur during high temperature curing, leading to the destruction of the spiro acetal structure to other structures, as can be explained from FTIR (FIG. 8 in the document).

Compared with the prior art, the invention has the following beneficial effects:

(1) The acetal structure is introduced into the main chain type benzoxazine resin, so that the resin can be endowed with degradability, and the recycling is facilitated; (2) The acetal introduced into the main chain type benzoxazine resin is spiro acetal, has certain rigidity, and endows the benzoxazine resin with better heat resistance in the curing process and heat resistance and rigidity of the cured resin; (3) The main chain type benzoxazine resin can reduce the curing temperature of a bisphthalonitrile compound containing an acetal structure; (4) The bi-phthalonitrile-based composite curing resin can be degraded under an acidic condition.

Drawings

Fig. 1 to 16 show DSC curves of the main chain benzoxazines obtained in comparative example 2, example 1, and examples 8 to 21 in this order. Fig. 17 to 32 show nuclear magnetic spectra of the main chain benzoxazines obtained in comparative example 2, example 1, and examples 8 to 21 in this order.

Detailed Description

While the present invention will be described in detail with reference to the following examples, it should be understood that the following examples are illustrative of the present invention and are not to be construed as limiting the scope of the present invention. Unless otherwise specified, reagents and equipment used in the following examples are commercially available products.

Preparation of pentaerythritol bis-m-hydroxyphthalimide reference is made to patent CN112010833A or to the literature "Ke Li, hua Yin, kun Yang, pei Dai, ling Han and Riwei xu. Synthesis and properties of phthalonitrile-based reacting carbonyl acid. High Performance Polymers 2020".

Test methods used in examples and comparative examples:

FTIR: IS-5 Fourier Infrared Spectroscopy, KBr pellet method;

H-NMR: bruker Avance 400MHz,25 ℃, deuterated chloroform; the possible n value is obtained by converting the integral area of H in the group R and H in the terminal hydroxyl in the nuclear magnetism result.

DSC: TQ100, 10 ℃/min, nitrogen atmosphere.

In the present invention, the degree (%) of degradation of the cured resin and the composite cured resin is calculated as shown in the following equation:

degree of degradation% = [1- (W1-W2)/W1 ]. Times.100%

Wherein W1 represents the initial weight of the cured resin and W2 represents the weight of the degraded and insoluble residue.

Comparative example 1

According to the ratio of phenolic hydroxyl group: amino group: aldehyde group =1:1:2.1 Weighing raw materials according to a molar ratio, and adding 2.28g (0.01 mol) of bisphenol A,1.83mL (0.02 mol) of aniline, 1.261g (0.042 mol) of paraformaldehyde and 50mL of toluene in a 100mL three-neck flask in sequence, wherein the paraformaldehyde is added in 2-4 times; the three-mouth bottle is firstly placed in a low-temperature constant-temperature reaction bath to be stirred for 30min, and then the temperature is gradually increased to 95 ℃ to react for 10h. After the reaction was completed, the product was washed with an aqueous sodium hydroxide solution (1M), filtered, washed with deionized water to neutrality, filtered, and dried under vacuum to a constant weight (50 ℃ C.), and then weighed to give a yield of 75.2%. Heating bisphenol A-aniline benzoxazine resin according to the temperature programming of 140,160,180 and 200 ℃, keeping each temperature for 1 hour, finally cooling to room temperature for curing, and using the obtained cured product for the subsequent chemical degradation comparative example; degradation experiments were carried out under the conditions of ethanol: water: acetic acid (0.1M) =4. The molecular structure of the product is shown below.

Example 1

According to the ratio of phenolic hydroxyl group: amino group: aldehyde group =1 (mole ratio) 2, and 3.44g (0.01 mol) of pentaerythritol bis-p-hydroxybenzaldehyde, 1.72g (0.01 mol) of decamethylene diamine, 1.20g (0.04 mol) of paraformaldehyde and 50mL of DMF were sequentially added to a 100mL three-necked flask, wherein the paraformaldehyde was added at one time; the reaction temperature was set at 115 ℃ and the reaction was carried out for 24h. After the reaction, the product was washed with aqueous sodium hydroxide (1M), filtered, washed with deionized water to neutrality, filtered, and dried under vacuum to constant weight (50 ℃), and weighed to yield 50.1%. The molecular structure of the product is shown below.

Example 2

According to the phenolic hydroxyl group: amino group: aldehyde =1 (molar ratio) in the following 2, the synthesis procedure was the same as in example 1 except that n-butanol was used as the solvent, the reaction temperature was 95 ℃, and the yield was 42.0%.

Example 3

According to the phenolic hydroxyl group: amino group: aldehyde group =1 (molar ratio).

Example 4

According to the ratio of phenolic hydroxyl group: amino group: aldehyde group = 1.2 (molar ratio) and raw materials were weighed, and the synthesis procedure was the same as in example 1, and the yield was 43.1%.

Example 5

According to the ratio of phenolic hydroxyl group: amino group: aldehyde =1, 2.4 (molar ratio) raw materials were weighed, and the synthesis procedure was the same as in example 1 except that the amount of paraformaldehyde was 1.441g (0.048 mol) and the yield was 48.6%.

Example 6

The synthesis procedure was the same as in example 1, except that the reaction time was 48h and the yield was 55.0%.

Example 7

The synthesis procedure was the same as in example 3, except that the reaction time was 12h and the yield was 35.3%.

Example 8

According to the phenolic hydroxyl group: amino group: aldehyde group = 1; the reaction temperature was set at 115 ℃ and the reaction was carried out for 24h. After the reaction was completed, the product was washed with an aqueous sodium hydroxide solution (1M), filtered, washed with deionized water to neutrality, filtered, and vacuum-dried to a constant weight (50 ℃ C.), and weighed to give a yield of 52.2%. The molecular structure of the product is shown below.

Example 9

According to the ratio of phenolic hydroxyl group: amino group: aldehyde group = 1; the reaction temperature was set at 115 ℃ and the reaction was carried out for 24h. After the reaction was completed, the product was washed with an aqueous sodium bicarbonate solution (0.5M), filtered, washed with deionized water to neutrality, filtered, and vacuum-dried to a constant weight (50 ℃ C.), and weighed to give a yield of 54.3%. The molecular structure of the product is shown below.

Example 10

The procedure was as in example 9 except that 0.60g (0.01 mol) of ethylenediamine was used instead of butanediamine, giving a yield of 56.3%. The molecular structure of the product is shown below.

Example 11

The procedure was the same as in example 9 except that 1.44g (0.01 mol) of octanediamine was used instead of butanediamine, and the yield was 52.8%. The molecular structure of the product is shown below.

Example 12

The procedure was as in example 9, except that 2.00g (0.01 mol) of 1, 12-diaminododecane was used in place of butanediamine, in 42.3% yield. The molecular structure of the product is shown below.

Example 13

The synthesis procedure was the same as in example 9 except that 1.98g (0.01 mol) of 4,4' -diaminodiphenylmethane was used instead of butanediamine, in a yield of 31.0%. The molecular structure of the product is shown below.

Example 14

The synthesis was identical to example 9, except that 2.48g (0.01 mol) of diaminodiphenyl sulfone was used instead of butanediamine, in a yield of 35.1%.

The molecular structure of the product is shown below.

Example 15

The synthesis was carried out in the same manner as in example 9 except that 2.38g (0.01 mol) of 4,4' -methylenebis (2-methylcyclohexylamine) was used in place of butanediamine, giving a yield of 65.0%. The molecular structure of the product is shown below.

Example 16

According to the ratio of phenolic hydroxyl group: amino group: aldehyde group = 1; the reaction temperature was set at 115 ℃ and the reaction was carried out for 24h. After the reaction was completed, the product was washed with an aqueous sodium bicarbonate solution (0.5M), filtered, washed with deionized water to neutrality, filtered, and vacuum-dried to a constant weight (50 ℃), and weighed to yield 49.3%. The molecular structure of the product is shown below.

Example 17

The procedure was carried out in the same manner as in example 16 except that 1.08g (0.01 mol) of p-phenylenediamine was used instead of decamethylenediamine, giving a yield of 48.1%. The molecular structure of the product is shown below.

Example 18

The procedure was followed as in example 16, except that 2.38g (0.01 mol) of 4,4' -methylenebis (2-methylcyclohexylamine) was used instead of decamethylenediamine, and the yield was 58.9%. The molecular structure of the product is shown below.

Example 19

According to the ratio of phenolic hydroxyl group: amino group: aldehyde group =1 (mole ratio) 2, and 3.44g (0.01 mol) of pentaerythritol bis-o-hydroxybenzaldehyde, 1.72g (0.01 mol) of decamethylene diamine, 1.20g (0.04 mol) of paraformaldehyde and 50mL of DMF were sequentially added to a 100mL three-necked flask, wherein the paraformaldehyde was added 1 time; the reaction temperature was set at 115 ℃ and the reaction was carried out for 24h. After the reaction was completed, the product was washed with an aqueous sodium bicarbonate solution (0.5M), filtered, washed with deionized water to neutrality, filtered, dried under vacuum to a constant weight (50 ℃ C.), and weighed to give a yield of 47.1%. The molecular structure of the product is shown below.

Example 20

The procedure was carried out in the same manner as in example 19 except that 1.08g (0.01 mol) of p-phenylenediamine was used instead of decamethylenediamine, giving a yield of 38.1%. The molecular structure of the product is shown below.

Example 21

The synthesis procedure was the same as in example 19 except that 2.38g (0.01 mol) of 4,4' -methylenebis (2-methylcyclohexylamine) was used instead of decamethylenediamine, resulting in a yield of 57.0%. The molecular structure of the product is shown below.

Comparative example 2

According to the phenolic hydroxyl group: amino group: aldehyde =1, 2.1 (molar ratio), weighing raw materials, adding 50mL of DMF,3.44g (0.01 mol) of pentaerythritol bis-p-hydroxybenzaldehyde and 1.83ml (0.02mo 1) of aniline in a 100ml three-neck flask in sequence, and stirring and mixing uniformly; adding 1.261g (0.042 mol) of paraformaldehyde into the three-neck flask for 2-4 times, firstly placing the three-neck flask into a low-temperature constant-temperature reaction bath, stirring for 30min, then gradually heating to 95 ℃, and reacting for 10h at constant temperature. After the reaction is finished, washing a reaction product by using a sodium hydroxide aqueous solution with the concentration of 1mol/L, filtering, washing by using deionized water to be neutral, filtering, and drying in vacuum at 50 ℃ to be constant weight.

Example 22 degradation Performance test of cured product of benzoxazine resin

The degradation performance of the benzoxazine resin containing an acetal structure is illustrated by the degradation of the cured product of pentaerythritol bis-p-hydroxybenzaldehyde-butanediamine main chain type benzoxazine resin.

Curing pentaerythritol bis-p-hydroxybenzaldehyde-butanediamine main chain type benzoxazine resin (the synthesis conditions are shown in example 9), wherein each temperature gradient is a temperature gradient at the temperature of 20 ℃, each temperature gradient reacts for 2 hours, and the temperature is increased from 140 ℃ to 220 ℃ to obtain a cured product. And (3) putting the cured product into different solutions for thermal degradation, filtering after degrading for a certain time, drying the filter paper to constant weight, and testing the degradation degree of the filter paper. The degradation conditions and results are listed in table 1.

TABLE 1 degradation behavior of cross-linked resin after curing of pentaerythritol bis p-hydroxybenzaldehyde-butanediamine main chain type benzoxazine resin

As can be seen from table 1 above, the cured resin cured by the main chain benzoxazine resin of the present invention has acidic degradability. The higher the degradation temperature, the longer the degradation time, and the stronger the acidity of the acidic solution for degradation, the more complete the degradation.

Example 23 Heat stability Properties

TGA measurements were made of the resins obtained in example and comparative example 2, respectively, and the structures are shown in Table 2 below.

Table 2: TGA data

Oxazine classes	T d5％ (℃)	T d10％ (℃)	Y c (780℃,％)
				Example 10	278.18	329.41	42.22
Example 9	312.84	355.91	40.19
				Example 8	324.40	363.29	37.94
Example 1	291.52	335.25	37.41
				Example 13	305.72	336.86	48.45
Example 16	307.70	344.49	35.18
				Example 17	282.23	315.87	43.13
Example 19	311.82	346.19	30.62
				Example 20	281.87	314.62	42.87
Comparative example 2	230.30	304.20	48.36

As can be seen from table 2, compared with the aniline benzoxazine, the main chain benzoxazine of the present invention has more excellent thermal stability, and the analysis reason may be that: the benzoxazine is endowed with a higher initial decomposition temperature due to the rigidity of the spiro structure, and the main chain type benzoxazine disclosed by the invention contains more spiro structures, so that the thermal stability of the benzoxazine is more excellent.

Example 24 degradation Properties of composite cured resin of benzoxazine resin and phthalonitrile Compound having a Spirocyclic Acetal Structure

Mixing the main chain type benzoxazine resin and pentaerythritol bis-m-hydroxyphthalic nitrile according to the weight ratio in the table 2 to obtain a composite material, then carrying out ring-opening curing on the composite material, wherein each temperature gradient is a temperature gradient at 20 ℃, each temperature gradient reacts for 2 hours, and the temperature is raised from 120 ℃ to 240 ℃ to obtain the composite cured resin.

And (3) putting the composite cured resin into different solutions for thermal degradation, filtering after degrading for a certain time, drying the filter paper to constant weight, and testing the degradation degree of the filter paper. The degradation conditions and results are listed in table 3.

TABLE 3 degradation behavior of composite cured resins

As can be seen from table 3, the composite cured resin was degraded under acidic conditions, and the degree of degradation exceeded the benzoxazine content thereof, indicating that the phthalonitrile resin therein was also degraded.

Experimental examples product testing

(1) The (p-SQ) -decamethylenediamine main chain type benzoxazine resin obtained in example 1 was examined:

the infrared detection results are as follows: 1501cm ^-1 The single peak is the stretching vibration peak of C-C on the benzene ring, 1383cm ^-1 with-CH of decamethylenediamine ₂ -absorption of the vibration peak; 1234cm ^-1 The position is a stretching vibration peak of a C-O-C bond on an oxazine ring; 1119cm ^-1 The position is a C-O characteristic peak of acetal, namely a C-O characteristic absorption peak of tertiary carbon connected with two O atoms in an acetal ring; 945cm ^-1 The peak is the absorption vibration peak of the oxazine ring; 1078cm ^-1 The position is a stretching vibration peak of C-O-C on an acetal ring; 1170cm ^-1 The peak is the oscillation peak of C-N-C on the oxazine ring. As can be seen, an oxazine ring is present. At 2844 and 2937cm ^-1 methylene-CH in the acetal ring can be observed ₂ -CH-asymmetric and symmetric stretching vibration absorption peaks on-. At 3500cm ^-1 A stretching vibration peak of-OH can be observed, and the two ends of the oxazine are free hydroxyl of acetal bisphenol.

The nuclear magnetic detection results are as follows: a newly appeared proton peak Ha at the chemical shift delta =5.42ppm and belongs to oxazine ring-O-CH ₂ -hydrogen on the middle carbon of the N-structure with proton peak Hg at chemical shift δ =5.39 ppm; a newly appeared proton peak Hb at the chemical shift delta =4.85ppm, belonging to oxazine ring Ar-CH ₂ -hydrogen on the middle carbon of the N-structure; because an oxazine ring is generated, the chemical shift and the split of hydrogen on a benzene ring are changed, and proton peaks Hi and Hj are both in the range of chemical shift delta =6.7-7.1 ppm; chemical shifts at four positions c, d, e and f on the intermediate spiro structure are also changed from original 4.5ppm-3.6ppm

4.9ppm to 3.6ppm. At 1.30,1.55, 2.71ppm-CH belonging to decamethylenediamine ₂ -structural hydrogen. Integral integration is carried out on some peaks to obtain S _a :S _b :S _g :S _(c+d+e+f) :S _i :S _j :S _k = 2.

The DSC shows that the first downward peak is a melting endothermic peak which is relatively wide and the melting peak temperature is about 150 ℃. The second upward peak is the curing exothermic peak of the oxazine, and the curing temperature of the (p-SQ) -decamethylene diamine main chain type benzoxazine is about 250 ℃. Around 280 ℃, a second upward curing exotherm peak occurs.

(2) (p-SQ) -hexamethylenediamine main chain type benzoxazine resin obtained in example 8 was examined

The infrared detection results are as follows: 1501cm ^-1 Is located at 1383cm which is a stretching vibration peak of C-C on a benzene ring ^-1 In the presence of-CH in hexamethylenediamine ₂ -absorption vibration peak of. 1119cm ^-1 The position is the C-O characteristic peak of the acetal, namely the C-O characteristic absorption peak of the tertiary carbon connected with two O atoms in the acetal ring. 1234cm ^-1 The position is a stretching vibration peak of a C-O-C bond on an oxazine ring; 945cm ^-1 The peak is the absorption vibration peak of the oxazine ring; 1078cm ^-1 Is located at the stretching vibration peak of C-O-C on an acetal ring, 1164cm ^-1 The position is the vibrational peak of C-N-C on the oxazine ring. It can be seen that there is an oxazine ring present. At 2849 and 2931cm ^-1 methylene-CH in the acetal ring can be observed ₂ -CH-asymmetric and symmetric stretching vibration absorption peaks on-. At 3526cm ^-1 A stretching vibration peak of-OH can be observed, which indicates that two ends of the oxazine are free hydroxyl of acetal bisphenol. At the same time, at 830cm ^-1 The characteristic peak of para-substitution of benzene ring disappears at 819, 888cm ^-1 The 1,2, 4-trisubstituted characteristic peak of the benzene ring appears. The (p-SQ) -hexamethylenediamine benzoxazine is successfully synthesized on the surface.

The nuclear magnetic detection results are as follows: at chemical shift δ =5.38ppm is the proton peak Ha, belonging to oxazine ring-O-CH ₂ -hydrogen on the middle carbon of the N-structure. Because no single proton peak at Hg is observed, the proton peak is judged to possibly coincide with the proton peak of Ha, and the proton peak can be judged to coincide through integral comparison. Delta =4.83ppm is the proton peak Hb, belonging to the oxazine ring Ar-CH ₂ -hydrogen on the middle carbon of the N-structure. Since the oxazine ring is formed, the chemical shift and split of hydrogen on the benzene ring are changed, and both proton peaks Hh, hi appear in the chemical shift δ =6.7-7.1ppm interval. In addition, chemical shifts at four positions c, d, e and f of the intermediate spiro structure are from 4.5ppm to 36ppm to 4.6ppm-3.6ppm. The peak Hk attributed to the proton on hexamethylenediamine appears at 1.29,1.49, 2.81ppm. Integrating the peak area of the image to obtain S _a :S _b :S _g :S _c+d+e+f :S _h :S _i :S _k 1 = 2.

The DSC shows that the first downward peak is the melting endothermic peak, the temperature is about 130 ℃, and the peak shape is wide. The second upward peak is the curing exothermic peak of the oxazine, and the curing temperature of the oxazine is about 280 ℃.

(3) (p-SQ) -butanediamine Main chain type benzoxazine resin obtained in example 9 was examined

The infrared detection results are as follows: 1501cm ^-1 Is located at 1383cm which is a stretching vibration peak of C-C on a benzene ring ^-1 In the form of-CH in butanediamine ₂ -absorption vibration peak of. 1233cm ^-1 The position is a stretching vibration peak of a C-O-C bond on an oxazine ring; 1119cm ^-1 The position is a C-O characteristic peak of acetal, namely a C-O characteristic absorption peak of tertiary carbon connected with two O atoms in an acetal ring; 950cm ^-1 The peak is the absorption vibration peak of the oxazine ring; 1078cm ^-1 Is a stretching vibration peak of C-O-C on an acetal ring; 1164cm ^-1 The position is also the vibrational peak of C-N-C on the oxazine ring. As can be seen, an oxazine ring is present. At 2849 and 2937cm ^-1 In the acetal ring is methylene-CH ₂ -CH-asymmetric and symmetric stretching shock absorption peaks on-are shown. At 3426cm ^-1 A stretching vibration peak of-OH can be observed, which indicates that two ends of the oxazine are free hydroxyl of acetal bisphenol.

The nuclear magnetic detection results are as follows: at chemical shift δ =5.64ppm is the proton peak Ha, belonging to oxazine ring-O-CH ₂ -hydrogen on the middle carbon of the N-structure. Delta =4.85ppm is the proton peak Hb, belonging to the oxazine ring Ar-CH ₂ -hydrogen on the middle carbon of the N-structure. Because an oxazine ring is generated, chemical shifts and splits of hydrogen on a benzene ring are changed, and proton peaks Hi and Hj both appear in a chemical shift δ =6.9-7.1ppm interval. In addition, c and d in the intermediate spiro structureChemical shifts of e and f are changed from 4.5ppm-3.6ppm to 4.9ppm-3.6ppm, and some proton peaks are overlapped with Hb. The peak Hk belonging to the proton on butanediamine is in the interval 1.0ppm-2.7 ppm. Integrating the peak area of the image to obtain S _a :S _b :S _g :S _c+d+e+f :S _i :S _j 1 = 2.

The DSC shows that the first downward peak is the melting endothermic peak, the melting peak top temperature is about 150 ℃, and the peak is very wide. The second upward peak is the curing exothermic peak of the oxazine, and the peak top temperature is about 256 ℃.

(4) Examination of the (p-SQ) -ethylenediamine Main-chain benzoxazine resin obtained in example 10

The infrared detection results are as follows: 1501cm ^-1 Is located at 1383cm which is a stretching vibration peak of C-C on a benzene ring ^-1 In the presence of-CH in ethylenediamine ₂ -absorption vibration peak of (a). 1242cm ^-1 The position is a stretching vibration peak of C-O-C on the oxazine ring; 1119cm ^-1 The position is a C-O characteristic peak of acetal, namely a C-O characteristic absorption peak of tertiary carbon connected with two O atoms in an acetal ring; 945cm ^-1 The peak is the absorption vibration peak of the oxazine ring; 1076cm ^-1 Is located at the stretching vibration peak of C-O-C on acetal, 1168cm ^-1 The position is the vibrational peak of C-N-C on the oxazine ring. As can be seen, an oxazine ring is present. At 2937 and 2849cm ^-1 In the acetal ring is methylene-CH ₂ -CH-asymmetric and symmetric stretching shock absorption peaks on-are shown. Furthermore, at 3426cm ^-1 A stretching vibration peak of-OH can be observed, which indicates that two ends of the oxazine are free hydroxyl of acetal bisphenol.

The nuclear magnetic detection results are as follows: at chemical shift δ =5.37ppm is the proton peak Ha, belonging to oxazine ring-O-CH ₂ -hydrogen on the middle carbon of the N-structure. And judging that the single proton peak at the Hg position is possibly overlapped with the proton peak at the Ha position because the single proton peak at the Hg position is not observed, and judging that the proton peaks are overlapped through integral comparison. Delta =4.62ppm appears as a proton peak Hb belonging to oxazine ring Ar-CH ₂ -N-structural intermediateHydrogen on carbon. Since the oxazine ring is formed, the chemical shift and split of hydrogen on the benzene ring are changed, and both proton peaks Hh and Hi appear in the chemical shift δ =6.7-7.1 ppm. Besides, chemical shifts at four positions of c, d, e and f on the intermediate spiro structure are changed from original 4.5ppm-3.6ppm to 4.9ppm-3.6ppm. The peak Hk attributed to the proton on ethylenediamine appeared at 2.82 ppm. Integrating the peak area of the image to obtain S _a :S _b :S _g :S _c+d+e+f :S _h :S _i :S _k 1 = 2.

The DSC chart shows that the first downward peak is the melting endothermic peak at about 80 ℃, probably because the main chain diamine has a low molecular weight and therefore has a low melting point. The second upward peak is the exothermic curing peak for oxazines, with an initial curing temperature of about 225 ℃ and a peak top temperature of about 277 ℃.

(5) (p-SQ) -octanediamine main chain type benzoxazine resin obtained in example 11 was examined

The infrared detection results are as follows: 1503cm ^-1 Is located at 1383cm which is a stretching vibration peak of C-C on a benzene ring ^-1 In the form of-CH in octanediamine ₂ -absorption vibration peak of (a). 1234cm ^-1 The position is a stretching vibration peak of C-O-C on the oxazine ring; 1119cm ^-1 The position is a C-O characteristic peak of acetal, namely a C-O characteristic absorption peak of tertiary carbon connected with two O atoms in an acetal ring; 950cm ^-1 The peak is the absorption vibration peak of the oxazine ring; 1076cm ^-1 Is located at the stretching vibration peak of C-O-C on acetal, 1166cm ^-1 The position is the vibrational peak of C-N-C on the oxazine ring. As can be seen, an oxazine ring is present. At 2931 and 2849cm ^-1 In the acetal ring as methylene-CH ₂ -CH-asymmetric and symmetric stretching vibration absorption peaks on-. Furthermore, at 3350cm ^-1 A stretching vibration peak of-OH can be observed, which indicates that two ends of the oxazine are free hydroxyl of acetal bisphenol.

The nuclear magnetic detection results are as follows: at chemical shift δ =5.38ppm is the proton peak Ha, belonging to oxazine ring-O-CH ₂ -N-structureHydrogen on the middle carbon. Delta =4.85ppm is the proton peak Hb, belonging to the oxazine ring Ar-CH ₂ -hydrogen on the middle carbon of the N-structure. Since the oxazine ring is generated, the chemical shift and split of hydrogen on the benzene ring are changed, and both proton peaks Hi, hj appear in the chemical shift δ =6.7-7.1ppm interval. In addition, chemical shifts at four positions c, d, e and f of the intermediate spiro structure are changed from 4.5ppm to 3.6ppm to 4.9ppm to 3.6ppm, and some proton peaks are overlapped with Hb. The proton peak Hk belonging to the octanediamine appears in the interval 1.3ppm to 2.7 ppm. The peak area of the graph is integrated to obtain S _a :S _b :S _g :S _c+d+e+f :S _i :S _j 1:2: 1, so it can be determined that (p-SQ) -octanediamine main chain benzoxazine was successfully synthesized, where n =7.6.

DSC detection shows that the downward peak at 80 ℃ is the melting peak of oxazine in a DSC picture. The upward peak is the curing exothermic peak of the oxazine, and the curing temperature of the oxazine is about 210 ℃. Around 251 ℃, a downward endothermic peak appears, probably because the oxazine is decomposed at high temperature.

(6) (p-SQ) -1, 12-diaminododecane main chain type benzoxazine obtained in example 12 was examined

The infrared detection results are as follows: 1504cm ^-1 The position is a C-C stretching vibration peak on a benzene ring; 1238cm ^-1 The position is a stretching vibration peak of C-O-C on the oxazine ring; 1116cm ^-1 The position is a C-O characteristic peak of acetal, namely a C-O characteristic absorption peak of tertiary carbon connected with two O atoms in an acetal ring; 918cm ^-1 The peak is the absorption vibration peak of the oxazine ring; 1072 and 829cm ^-1 The position is a stretching vibration peak of C-O-C on an acetal ring; further, 829cm ^-1 The position is also the vibration peak of C-N-C on the oxazine ring. 2924 and 2850cm ^-1 In the form of CH carried on 1, 12-diaminododecane ₂ 、CH ₃ The peak of vibration of (1). As can be seen, an oxazine ring is present.

The nuclear magnetic detection results are as follows: at chemical shift δ =5.38ppm is the proton peak Ha, belonging to oxazine ring-O-CH ₂ Hydrogen on the middle carbon of the N-structure and protons at HgThe peak coincides with Ha. Delta =4.55ppm is the proton peak Hb, belonging to the oxazine ring Ar-CH ₂ -hydrogen on the middle carbon of the N-structure. Since the oxazine ring is generated, the chemical shift and split of hydrogen on the benzene ring are changed, and proton peaks Hi, hj both appear in the chemical shift δ =6.7-7.2ppm interval. In addition, chemical shifts at four positions of c, d, e and f on the intermediate spiro structure are changed from 4.5ppm-3.6ppm to 4.9ppm-3.6ppm. The peak Hk of the proton belonging to diaminododecane appears in the range of 1.3ppm to 2.7ppm, probably because of the greater solubility, and therefore the peak area ratio has a slight deviation, but the position of the peak appearance is accurate. Integrating the peak area of the image to obtain S _a :S _b :S _g :S _c+d+e+f :S _i :S _j 1.

DSC shows that a wider melting peak is formed at 120 ℃ and an upward exothermic peak is formed at 160 ℃. Two curing exothermic peaks of oxazine appear at 236 ℃ and 278 ℃.

(7) (p-SQ) -4,4' -diaminodiphenylmethane major chain benzoxazine obtained in example 13 was examined

The infrared detection results are as follows: 1506cm ^-1 The position is a C-C stretching vibration peak on a benzene ring; 1233cm ^-1 The position is a stretching vibration peak of C-O-C on the oxazine ring; 1114cm ^-1 The position is a C-O characteristic peak of acetal, namely a C-O characteristic absorption peak of tertiary carbon connected with two O atoms in an acetal ring; 938cm ^-1 The peak is the absorption vibration peak of the oxazine ring; 1077cm ^-1 Is a stretching vibration peak of C-O-C on an acetal ring; 1170cm ^-1 The peak is the vibration peak of C-N-C on the oxazine ring. 824cm ^-1 The peak is a peak of para-substituted benzene ring, and the peak value is higher, compared with aliphatic main chain type oxazine, the peak is obviously improved, so that the main chain of the oxazine contains a 4,4' -diaminodiphenylmethane structure. At 2910 and 2837cm ^-1 In the form of-CH on 4,4' -diaminodiphenylmethane ₂ -peak oscillation, small because the carbon chain is short. In addition, at 3426cm ^-1 Can be seenThe stretching vibration peak of-OH is observed, and the two ends of the oxazine are free hydroxyl of acetal bisphenol. As can be seen, an oxazine ring is present.

The nuclear magnetic detection results are as follows: at chemical shift δ =5.38ppm is the proton peak Ha, belonging to oxazine ring-O-CH ₂ Hydrogen on the middle carbon of the-N-structure, and the proton peak at Hg coincides with Ha. Delta =4.54ppm is the proton peak Hb, belonging to the oxazine ring Ar-CH ₂ -hydrogen on the middle carbon of the N-structure. Since the oxazine ring is generated, the chemical shift and split of hydrogen on the benzene ring are changed, and proton peaks Hi, hj both appear in the chemical shift δ =6.7-7.2ppm interval. Besides, chemical shifts at four positions of c, d, e and f on the intermediate spiro structure are changed from original 4.5ppm-3.6ppm to 4.9ppm-3.6ppm. The proton peak Hk attributed to methylene group on 4,4' -diaminodiphenylmethane appeared at 3.83 ppm. Integrating the peak area of the image to obtain S _a :S _b :S _g :S _c+d+e+f :S _i :S _j :S _k 1 = 2.

The DSC shows that the first downward broad peak is the melting endothermic peak at about 110 ℃ as detected by DSC, probably because the main chain diamine is a mixture, so the melting point is low and broad. The second upward peak is the curing exothermic peak of the oxazine, and the curing temperature is about 263 ℃.

(8) (p-SQ) -diaminodiphenyl sulfone main chain benzoxazine resin obtained in example 14 was examined

The infrared detection results are as follows: 1501cm ^-1 Is located at the stretching vibration peak of C-C on a benzene ring, 1234cm ^-1 The position is a stretching vibration peak of C-O-C on the oxazine ring; 948cm ^-1 The peak is the absorption vibration peak of the oxazine ring; 1083cm ^-1 Located as the stretching vibration peak of C-O-C on acetal, 1160cm ^-1 The position is the vibrational peak of C-N-C on the oxazine ring. As can be seen, an oxazine ring is present. At 1290cm ^-1 Is the vibrational peak of the sulfone. Furthermore, at 3400cm ^-1 A stretching vibration peak of-OH can be observed, which indicates that two ends of the oxazine are acetal bisFree hydroxyl group of phenol.

The nuclear magnetic detection results are as follows: the proton peak Ha is at the chemical shift delta =5.29ppm and belongs to oxazine ring-O-CH ₂ -hydrogen on the middle carbon of the N-structure. Delta =4.85ppm is the proton peak Hb, belonging to the oxazine ring Ar-CH ₂ -hydrogen on the middle carbon of the N-structure. Since the oxazine ring is generated, the chemical shift and split of hydrogen on the benzene ring are changed, and both proton peaks Hi, hj appear in the chemical shift δ =6.7-7.1ppm interval. In addition, chemical shifts at four positions c, d, e and f of the intermediate spiro structure are changed from 4.5ppm to 3.6ppm to 4.9ppm to 3.6ppm, and some proton peaks are overlapped with Hb. The proton peaks Hk and Hl belonging to diamino-diphenyl-sulfone appear at 6.72ppm and 7.63ppm, respectively. Integrating the peak area of the image to obtain S _a :S _b :S _g :S _c+d+e+f :S _i :S _j :S _k :S _l 1:2, 1.

DSC detection shows that a downward melting peak is observed at 93 ℃, two smaller upward peaks are observed at 132 ℃ and 163 ℃, and an exothermic solidification peak of oxazine appears at a high temperature of 302 ℃. Since dioxy diphenyl sulfone is a curing agent with excellent heat resistance, the sulfur atom in its molecular structure is already in the highest oxidation state, and the sulfone group tends to attract electrons on the benzene ring to make the benzene ring lack electrons, so that the entire diphenyl sulfone group is in an oxidation-resistant state. The incorporation of diaminodiphenyl sulfone into the backbone significantly increases the curing temperature of oxazines.

(9) (p-SQ) -4,4' -methylenebis (2-methylcyclohexylamine) main chain type benzoxazine resin obtained in example 15 was examined

The infrared detection results are as follows: 1501cm ^-1 Is at a stretching vibration peak of C-C on a benzene ring, 1378cm ^-1 In the presence of-CH in 4,4' -methylenebis (2-methylcyclohexylamine) ₂ -absorption vibration peak of. 1452cm ^-1 The peak is the characteristic peak of methyl in amine. 1234cm ^-1 The position is a stretching vibration peak of C-O-C on the oxazine ring; 1119cm ^-1 The position is a C-O characteristic peak of acetal, namely a C-O characteristic absorption peak of tertiary carbon connected with two O atoms in an acetal ring; 945cm ^-1 The peak is the absorption vibration peak of the oxazine ring; 1078cm ^-1 Is located at the stretching vibration peak of C-O-C on acetal, 1164cm ^-1 The peak is the oscillation peak of C-N-C on the oxazine ring. As can be seen, an oxazine ring is present. At 2925 and 2847cm ^-1 In the acetal ring is methylene-CH ₂ -CH-asymmetric and symmetric stretching shock absorption peaks on-are shown. Furthermore, at 3400cm ^-1 A stretching vibration peak of-OH can be observed, and the two ends of the oxazine are free hydroxyl of acetal bisphenol. 826cm ^-1 The position is a characteristic peak of para-position substitution of a benzene ring.

The nuclear magnetic detection results are as follows: at chemical shift δ =5.42ppm is the proton peak Ha, belonging to oxazine ring-O-CH ₂ Hydrogen on the middle carbon of the N-structure, proton peak at Hg at 5.38 ppm. Delta =4.86ppm appearing is the proton peak Hb, belonging to oxazine ring Ar-CH ₂ -hydrogen on the middle carbon of the N-structure. Because an oxazine ring is generated, chemical shifts and splits of hydrogen on a benzene ring are changed, and proton peaks Hi and Hj both appear in a chemical shift δ =6.7-7.2ppm interval. In addition, chemical shifts at four positions c, d, e and f of the intermediate spiro structure are changed from 4.5ppm to 3.6ppm to 4.9ppm to 3.6ppm, and some proton peaks are overlapped with Hb. Proton peaks Hk and Hm belonging to the methylene group and the methyl group on 4,4' -methylenebis (2-methylcyclohexylamine) appear at 3.83ppm and 2.36ppm, respectively. The peak area of the graph is integrated to obtain S _a :S _b :S _g :S _c+d+e+f :S _i :S _j :S _k :S _m 1.

DSC shows that a melting peak is downward and wider at 80 ℃ and two exothermic peaks are upward and smaller at 120 ℃ and 145 ℃. The curing exotherm of oxazines is at 240 ℃.

(10) (m-SQ) -decamethylenediamine Main-chain benzoxazine resin obtained in example 16 was examined

The infrared detection results are as follows: 1490cm ^-1 Is located at 1378cm of a stretching vibration peak of C-C on a benzene ring ^-1 In the form of-CH in decamethylenediamine ₂ -absorption vibration peak of (a). 1234cm ^-1 The position is a stretching vibration peak of C-O-C on the oxazine ring; 950cm ^-1 The peak is the absorption vibration peak of the oxazine ring; 1078cm ^-1 Is located at the stretching vibration peak of C-O-C on acetal, 1168cm ^-1 The peak is the oscillation peak of C-N-C on the oxazine ring. As can be seen, an oxazine ring is present. At 2931 and 2849cm ^-1 In the acetal ring is methylene-CH ₂ -CH-asymmetric and symmetric stretching vibration absorption peaks on-. In addition, at 3400cm ^-1 A stretching vibration peak of-OH can be observed, and the two ends of the oxazine are free hydroxyl of acetal bisphenol. At 870 and 800cm ^-1 The peak appears as the asymmetric 1,2, 4-trisubstituted characteristic peak of the benzene ring, and the C-H out-of-plane bending vibration peak belonging to the disubstituted between the benzene rings is also 887cm ^-1 、756cm ^-1 And 714cm ^-1 And disappear.

The nuclear magnetic detection results are as follows: at chemical shift δ =5.68ppm is the proton peak Ha, belonging to oxazine ring-O-CH ₂ -hydrogen on the middle carbon of the N-structure. Delta =4.86ppm is the proton peak Hb, belonging to the oxazine ring Ar-CH ₂ -hydrogen on the middle carbon of the N-structure. Because an oxazine ring is generated, chemical shifts and splits of hydrogen on a benzene ring are changed, and chemical shifts of the positions c, d, e and f on the middle spiro structure are also changed from original 4.5ppm-3.6ppm to 4.9ppm-3.6ppm. At 1.30,1.66,2.72ppm of-CH belonging to decamethylenediamine ₂ -structural hydrogen. Integrating the peak area of the image to obtain S _a :S _b :S _g :S _c+d+e+f :S _h 2 = 2.

DSC detection shows that a wide downward melting peak is observed at 127 ℃, and an upward oxazine curing peak appears at 222 ℃.

(12) (m-SQ) -p-phenylenediamine Main-chain benzoxazine resin obtained in example 17 was examined

Infrared detectionThe measurement results are as follows: 1501cm ^-1 The position is a stretching vibration peak of C-C on a benzene ring. 1109cm ^-1 The position is the C-O characteristic peak of the acetal, namely the C-O characteristic absorption peak of the tertiary carbon connected with two O atoms in the acetal ring. The position of 1234cm-1 is a stretching vibration peak of C-O-C on the oxazine ring; 950cm ^-1 The peak is the absorption vibration peak of the oxazine ring; 1076cm ^-1 Is located at the stretching vibration peak of C-O-C on acetal, 1164cm ^-1 The position is the vibrational peak of C-N-C on the oxazine ring. As can be seen, an oxazine ring is present. At 2956 and 2844cm ^-1 In the acetal ring is methylene-CH ₂ -CH-asymmetric and symmetric stretching shock absorption peaks on-are shown. Furthermore, at 3400cm ^-1 A stretching vibration peak of-OH can be observed, which indicates that two ends of the oxazine are free hydroxyl of acetal bisphenol. At 881 and 821cm ^-1 The peak appears at 830cm, which is the characteristic peak of asymmetric 1,2, 4-trisubstitution of benzene ring ^-1 The position is a characteristic peak of para-position substitution of a benzene ring, which indicates that p-phenylenediamine is successfully grafted. The peak of the out-of-plane bending vibration of C-H which belongs to benzene ring disubstituted is also from 887cm ^-1 、756cm ^-1 And 714cm ^-1 And disappear.

The nuclear magnetic detection results are as follows: at chemical shift delta =5.41ppm is the proton peak Ha belonging to oxazine ring-O-CH ₂ -hydrogen on the middle carbon of the N-structure. And the proton peak at Hg coincides with Ha. Delta =4.52ppm appearing is the proton peak Hb, belonging to oxazine ring Ar-CH ₂ -hydrogen on the middle carbon of the N-structure. Because an oxazine ring is generated, chemical shifts and splits of hydrogen on a benzene ring are changed, and chemical shifts of the positions c, d, e and f on the middle spiro structure are also changed from original 4.5ppm-3.6ppm to 4.9ppm-3.6ppm. The Hi is the proton peak in p-phenylenediamine. Integrating the peak area of the image to obtain S _a :S _b :S _g :S _c+d+e+f Si = 2.

DSC shows that a wider melting peak exists at 77 ℃. A plateau appeared at 120 ℃ to 144 ℃, presumably to reach the rubber plateau, and oxazines were flowable. Two curing peaks appear at 186 ℃ and 234 ℃.

(13) (m-SQ) -4,4' -methylenebis (2-methylcyclohexylamine) main chain type benzoxazine resin obtained in example 18 was examined

The infrared detection results are as follows: 1109cm ^-1 The position is the C-O characteristic peak of the acetal, namely the C-O characteristic absorption peak of the tertiary carbon connected with two O atoms in the acetal ring. 1383cm ^-1 In the presence of-CH in 4,4' -methylenebis (2-methylcyclohexylamine) ₂ -absorption vibration peak of. 1459cm ^-1 The peak is the characteristic peak of methyl in amine. 1235cm ^-1 The position is a stretching vibration peak of C-O-C on the oxazine ring; 945cm ^-1 The peak is the absorption vibration peak of the oxazine ring; 1078cm ^-1 Is located at the stretching vibration peak of C-O-C on acetal, 1168cm ^-1 The position is the vibrational peak of C-N-C on the oxazine ring. As can be seen, an oxazine ring is present. At 2950 and 2844cm ^-1 In the acetal ring is methylene-CH ₂ -CH-asymmetric and symmetric stretching shock absorption peaks on-are shown. Furthermore, at 3400cm ^-1 A stretching vibration peak of-OH can be observed, and the two ends of the oxazine are free hydroxyl of acetal bisphenol. At 880 and 819cm ^-1 The peak appears as the asymmetric 1,2, 4-trisubstituted characteristic peak of the benzene ring, and the C-H out-of-plane bending vibration peak belonging to the disubstituted between the benzene rings also has the length of 887cm ^-1 、 756cm ^-1 And 714cm ^-1 Where it disappears.

The nuclear magnetic detection results are as follows: a proton peak Ha at the chemical shift delta =5.42ppm and belongs to oxazine ring-O-CH ₂ Hydrogen on the middle carbon of the-N-structure, and the proton peak at Hg coincides with Ha. Delta =4.83ppm appears as a proton peak Hb belonging to oxazine ring Ar-CH ₂ -hydrogen on the middle carbon of the N-structure. Since the oxazine ring is generated, the chemical shift and split of hydrogen on the benzene ring are changed, and proton peaks Hi, hj both appear in the chemical shift δ =6.7-7.2ppm interval. In addition, chemical shifts at four positions of c, d, e and f on the intermediate spiro structure are changed from 4.5ppm-3.6ppm to 4.9ppm-3.6ppm, and some proton peaks are overlapped with Hb. Proton peaks Hk and Hm belonging to methylene and methyl groups on 4,4' -methylenebis (2-methylcyclohexylamine) appear at 3.83ppm and 2.33ppm, respectively. Subjecting the plot to peak area productDivide to obtain S _a :S _b :S _g :S _c+d+e+f :S _i :S _j :S _k :S _m 2. Since the oxazine peak was observed and the ratio was essentially correct, it was determined that (m-SQ) -4,4' -methylenebis (2-methylcyclohexylamine) backbone-type benzoxazines were successfully synthesized, where n =5.9.

DSC shows that there is a downward melting peak at 83 ℃, two smaller upward curing peaks at 114 ℃ and 130 ℃, which is presumed to be the destruction of the cyclic amine ring structure, and a larger upward oxazine curing peak at 198 ℃.

(14) (o-SQ) -decamethylenediamine Main-chain benzoxazine resin obtained in example 19 was examined

The infrared detection results are as follows: 1501cm ^-1 Is located at 1383cm which is a stretching vibration peak of C-C on a benzene ring ^-1 In the form of-CH in decamethylenediamine ₂ -absorption vibration peak of (a). 1234cm ^-1 The position is a stretching vibration peak of C-O-C on the oxazine ring; 1111cm ^-1 The position is a C-O characteristic peak of acetal, namely a C-O characteristic absorption peak of tertiary carbon connected with two O atoms in an acetal ring; 945cm ^-1 The peak is the absorption vibration peak of the oxazine ring; 1078cm ^-1 Is located at the stretching vibration peak of C-O-C on acetal, 1164cm ^-1 The peak is the oscillation peak of C-N-C on the oxazine ring. As can be seen, an oxazine ring is present. At 2931 and 2849cm ^-1 In the acetal ring is methylene-CH ₂ -CH-asymmetric and symmetric stretching vibration absorption peaks on-. In addition, at 3400cm ^-1 A stretching vibration peak of-OH can be observed, and the two ends of the oxazine are free hydroxyl of acetal bisphenol. At 810, 760 and 701cm ^-1 The peak appears as the continuous 1,2, 3-trisubstituted characteristic peak of the benzene ring.

The nuclear magnetic detection results are as follows: at chemical shift δ =5.74ppm is the proton peak Ha, belonging to oxazine ring-O-CH ₂ -hydrogen on the middle carbon of the N-structure, with proton peak Hg at δ =5.72 ppm. Delta =4.86ppm appearing is the proton peak Hb, belonging to oxazine ring Ar-CH ₂ -hydrogen on the middle carbon of the N-structure. On the benzene ring, as an oxazine ring is formedThe chemical shifts and the splits of hydrogen are changed, the chemical shifts of the four positions of c, d, e and f on the middle spiral ring structure are also changed from 4.5ppm-3.6ppm to 4.9ppm-3.6ppm, and proton peaks Hi and Hj are all in the chemical shift range of delta =6.7-7.1 ppm. 1.26,1.47,2.62ppm of-CH belonging to decamethylenediamine ₂ -structural hydrogen. The peak area of the graph is integrated to obtain S _a :S _b :S _g :S _c+d+e+f :S _i :S _j :S _h 1.

DSC shows that a downward melting peak is observed at 70 ℃, and upward oxazine curing peaks appear at 165 ℃ and 226 ℃.

(15) (o-SQ) -p-phenylenediamine Main-chain benzoxazine resin obtained in example 20 was examined

The infrared detection results are as follows: 1503cm ^-1 The position is a stretching vibration peak of C-C on a benzene ring. 1234cm ^-1 The position is a stretching vibration peak of C-O-C on the oxazine ring; 1109cm ^-1 The position is a C-O characteristic peak of acetal, namely a C-O characteristic absorption peak of tertiary carbon connected with two O atoms in an acetal ring; 945cm ^-1 The peak is the absorption vibration peak of the oxazine ring; 1078cm ^-1 Is located at the stretching vibration peak of C-O-C on acetal, 1164cm ^-1 The position is the vibrational peak of C-N-C on the oxazine ring. As can be seen, an oxazine ring is present. At 2950 and 2849cm ^-1 In the acetal ring is methylene-CH ₂ -CH-asymmetric and symmetric stretching vibration absorption peaks on-. Furthermore, at 3401cm ^-1 A stretching vibration peak of-OH can be observed, which indicates that two ends of the oxazine are free hydroxyl of acetal bisphenol. At 810, 760 and 701cm ^-1 The peak appears as the continuous 1,2, 3-trisubstituted characteristic peak of the benzene ring. At 810cm ^-1 The position is also the characteristic peak of para-substitution of benzene ring, and the two are slightly overlapped. Indicating that p-phenylenediamine has been successfully grafted.

The nuclear magnetic detection results are as follows: the proton peak Ha is at the chemical shift delta =5.30ppm and belongs to oxazine ring-O-CH ₂ -hydrogen on the middle carbon of the N-structure. And the proton peak at Hg is coincident with Ha. Delta =4.52ppm appearing is the proton peak Hb, belonging to oxazine ring Ar-CH ₂ -hydrogen on the middle carbon of the N-structure. Because an oxazine ring is generated, chemical shifts and splits of hydrogen on a benzene ring are changed, and chemical shifts of the positions c, d, e and f on the middle spiro structure are also changed from original 4.5ppm-3.6ppm to 4.9ppm-3.6ppm. The Hi is the proton peak in p-phenylenediamine. The peak area of the graph is integrated to obtain S _a :S _b :S _g :S _c+d+e+f Si = 2.

DSC shows that a downward melting peak is observed at 55 ℃, a small and unobvious upward solidification peak is observed at 156 ℃, and an obvious upward exothermic oxazine solidification peak is observed at 255 ℃.

(16) (o-SQ) -4,4' -methylenebis (2-methylcyclohexylamine) main chain type benzoxazine obtained in example 21 was examined

The infrared detection results are as follows: 1501cm ^-1 The position is a stretching vibration peak of C-C on a benzene ring. 1383cm ^-1 In the presence of-CH in 4,4' -methylenebis (2-methylcyclohexylamine) ₂ -absorption vibration peak of. 1452cm ^-1 The peak is the characteristic peak of methyl in amine. 1237cm ^-1 The position is a stretching vibration peak of C-O-C on the oxazine ring; 1114cm ^-1 The position is a C-O characteristic peak of acetal, namely a C-O characteristic absorption peak of tertiary carbon connected with two O atoms in an acetal ring; 945cm ^-1 The peak is the absorption vibration peak of the oxazine ring; 1078cm ^-1 Is located at the stretching vibration peak of C-O-C on acetal, 1164cm ^-1 The position is the vibrational peak of C-N-C on the oxazine ring. As can be seen, an oxazine ring is present. At 2920 and 2849cm ^-1 In the acetal ring by methylene-CH ₂ -CH-asymmetric and symmetric stretching vibration absorption peaks on-. In addition, at 3400cm ^-1 A stretching vibration peak of-OH can be observed, and the two ends of the oxazine are free hydroxyl of acetal bisphenol. At 813, 760 and 703cm ^-1 The peak appears as the continuous 1,2, 3-trisubstituted characteristic peak of the benzene ring.

The nuclear magnetic detection results are as follows: at chemical shift δThe proton peak Ha at 5.70ppm belongs to oxazine ring-O-CH ₂ Hydrogen on the middle carbon of the-N-structure, and the proton peak at Hg coincides with Ha. Delta =4.58ppm is the proton peak Hb, belonging to the oxazine ring Ar-CH ₂ -hydrogen on the middle carbon of the N-structure. Because an oxazine ring is generated, chemical shifts and splits of hydrogen on a benzene ring are changed, and proton peaks Hi and Hj both appear in a chemical shift δ =6.7-7.2ppm interval. In addition, chemical shifts at four positions of c, d, e and f on the intermediate spiro structure are changed from 4.5ppm-3.6ppm to 4.9ppm-3.6ppm. Proton peaks Hk and Hm belonging to the methylene group and the methyl group on 4,4' -methylenebis (2-methylcyclohexylamine) appear at 3.86ppm and 2.20ppm, respectively. The peak area integration of the graphs resulted in a ratio of Sa: sb: sg: sc + d + e + f: si: sj: sk: sm = 2.

DSC detection shows that there is a downward exothermic melting peak at 112 ℃ and two upward oxazine curing peaks at 152 ℃ and 202 ℃ in a DSC chart. There was a downward peak at 257 deg.C, presumably due to decomposition of the oxazine.

(17) Detection of the pentaerythritol diacetal p-hydroxybenzaldehyde-aniline benzoxazine obtained in comparative example 2

The infrared detection results are as follows: 1600 and 1501cm ^-1 The position is a stretching vibration peak of C-C on a benzene ring; the positions 1242 and 1031cm < -1 > are respectively the asymmetric stretching vibration peak and the symmetric stretching vibration peak of a C-O-C bond on an oxazine ring; the 947cm-1 part is an absorption vibration peak of the oxazine ring; 1077 and 824cm ^-1 The peak is the vibrational peak of C-O-C on the acetal ring, in addition 824cm ^-1 The position is also the vibration peak of C-N-C on the oxazine ring. As can be seen, an oxazine ring is present.

The nuclear magnetic detection results are as follows: a newly appeared proton peak Ha at the chemical shift delta =4.60ppm, belonging to hydrogen on the middle carbon of the oxazine ring N-C structure; chemical shift delta =5.38ppm belongs to proton peaks Hb and Hc, and corresponding peak areas S _b+c :S _a 2, also satisfying the respective hydrogen ratios; d, e, f and g on the intermediate spiro structureThe chemical shift of the hydrogen is changed from 4.5ppm to 3.6ppm to 4.9ppm to 3.6ppm, and the chemical shifts of two kinds of hydrogen are overlapped. Integral integration S of some peaks _a :S _b+c :S _d :S _e ∶S _f :S _g ∶S _{(h+i+j+k+l+m)} 1. It was confirmed that (p-SQ) -aniline benzoxazine was successfully synthesized (CDCl at delta =7.29 ppm) ₃ Solvent peak of (1).

The DSC chart shows that the first downward peak is the melting endothermic peak, and the melting peak top temperature is about 155 ℃. The second upward peak is the exothermic curing peak of the oxazine, and the initial curing temperature of the (p-SQ) -aniline benzoxazine is 180 ℃, and the peak top temperature is about 227 ℃. Around 290 ℃, a downward endothermic peak begins to appear, probably because the oxazine is decomposed at high temperature.

The invention has been described in detail with reference to specific embodiments and illustrative examples, but the description is not intended to be construed in a limiting sense. Those skilled in the art will appreciate that various equivalent substitutions, modifications or improvements may be made to the embodiments and implementations of the invention without departing from the spirit and scope of the invention, and are within the scope of the invention. The scope of the invention is defined by the appended claims.

Claims (13)

1. A main chain type benzoxazine resin is a polymer, wherein the molecular chain of the polymer contains at least one of repeating units shown in formulas (I-1) to (I-3):

in the formulas (I-1) to (I-3), each R is independently selected from at least one of an aliphatic group and a derivative thereof, an alicyclic group and a derivative thereof, and an aromatic group and a derivative thereof.

2. The main chain benzoxazine resin according to claim 1, wherein the molecular chain of the polymer has two terminals, one terminal is a structure represented by one of formulas (II-1) to (II-3), and the other terminal is a structure represented by one of formulas (III-1) to (III-3):

in the formulae (II-1) to (II-3) and the formulae (III-1) to (III-3), R has the same meaning as that of R in the formulae (I-1) to (I-3).

3. The main chain benzoxazine resin according to claim 1 or 2, wherein in formulae (I-1) to (I-3), each R is independently selected from at least one of a C2 to C20 alkyl group and a derivative thereof, a C6 to C20 aryl group and a derivative thereof, a C6 to C20 alicyclic group and a derivative thereof;

preferably, in the formulas (I-1) to (I-3), each R is independently selected from at least one of C2-C10 alkyl, C6-C10 aryl and derivatives thereof, and C6-C10 cyclohexyl and derivatives thereof.

4. A method of preparing the main chain benzoxazine resin according to any one of claims 1 to 3, comprising: the main chain type benzoxazine resin is obtained by reacting raw materials including bisphenol compounds, diamine compounds and aldehyde compounds containing spiro acetal structures.

5. The method according to claim 4, wherein the bisphenol compound containing a spiro acetal structure is at least one selected from the group consisting of pentaerythritol bis-p-hydroxybenzaldehyde represented by formula (II), pentaerythritol bis-m-hydroxybenzaldehyde represented by formula (III), pentaerythritol bis-o-hydroxybenzaldehyde represented by formula (IV), and derivatives thereof:

6. the method according to claim 4,

the diamine compound is at least one selected from aliphatic diamine and derivatives thereof, aromatic diamine and derivatives thereof, and alicyclic diamine and derivatives thereof; preferably at least one selected from the group consisting of C2-C20 aliphatic diamines and derivatives thereof, C6-C20 aryl diamines and derivatives thereof, and C6-C20 alicyclic diamines and derivatives thereof; and/or the presence of a gas in the atmosphere,

the aldehyde compound is selected from paraformaldehyde and/or aqueous formaldehyde solution, preferably paraformaldehyde.

7. The preparation method according to claim 4, wherein the ratio of the bisphenol compound containing the spirocyclic acetal structure, the diamine compound and the aldehyde compound is 1.

8. Preparation process according to one of claims 4 to 7, characterized in that it comprises the following steps:

step 1, mixing the aldehyde compound, the bisphenol compound containing the spiro acetal structure and the diamine compound with a solvent, and stirring;

and 2, heating to react, and performing post-treatment after the reaction is finished to obtain the main chain type benzoxazine resin.

9. The method according to claim 8,

in step 1, the solvent is selected from one or more of ethanol, methanol, isopropanol, butanol, isobutanol, tetrahydrofuran, dioxane, toluene, dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone; and/or the presence of a gas in the atmosphere,

in the step 2, the reaction temperature is 80-150 ℃, preferably 90-130 ℃; and/or the presence of a gas in the atmosphere,

in step 2, the reaction is carried out for 15 to 35 hours, preferably 20 to 30 hours; and/or the presence of a gas in the gas,

in step 2, the post-treatment includes alkali washing, water washing and solvent removal treatment.

10. A main chain type benzoxazine resin obtained by the production method according to any one of claims 4 to 9.

11. A bisphthalonitrile-based composite material, which comprises a main chain type benzoxazine resin and a bisphthalonitrile-based compound containing a spiro acetal structure, wherein the main chain type benzoxazine resin is selected from the main chain type benzoxazine resin in any one of claims 1 to 3 or the main chain type benzoxazine obtained by the method in any one of claims 4 to 9.

12. The bisphthalonitrile-based composite material according to claim 11, wherein the benzoxazine is present in an amount of 10-90 wt%, preferably 10-50 wt%, based on 100wt% of the total weight of the bisphthalonitrile-based composite material; the proportion of the bisphthalonitrile compound containing a spiro acetal structure is 10-90 wt%, and preferably 50-90 wt%.

13. A bisphthalonitrile-based composite cured resin which is a ring-opening cured product of the bisphthalonitrile-based composite material according to claim 11 or 12, preferably, the ring-opening curing is performed at 120 to 240 ℃; preferably, the temperature is increased from 120 ℃ to 240 ℃, each temperature gradient is 10-30 ℃, and each temperature gradient is reacted for 1-3 hours.

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