CN115403724B

CN115403724B - Main chain type benzoxazine resin, preparation method thereof, bisphthalonitrile-based composite material containing main chain type benzoxazine resin and composite curing resin

Info

Publication number: CN115403724B
Application number: CN202110585411.1A
Authority: CN
Inventors: 徐日炜; 胡中源; 韩翎; 张韬毅; 祝桂香; 张伟; 许宁; 计文希; 陈婧; 王蔼廉
Original assignee: Sinopec Beijing Research Institute of Chemical Industry; China Petroleum and Chemical Corp; Beijing University of Chemical Technology
Current assignee: Sinopec Beijing Research Institute of Chemical Industry; China Petroleum and Chemical Corp; Beijing University of Chemical Technology
Priority date: 2021-05-27
Filing date: 2021-05-27
Publication date: 2024-11-19
Anticipated expiration: 2041-05-27
Also published as: CN115403724A

Abstract

The invention discloses a main chain type benzoxazine resin, a preparation method thereof, a bisphthalonitrile-based composite material containing the main chain type benzoxazine resin and a composite curing resin, wherein the main chain type benzoxazine resin is a polymer, and the molecular chain of the main chain type benzoxazine resin contains at least one of the 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 benzoxazines, in particular to a main chain type benzoxazine resin, a composite curing resin containing the main chain type benzoxazine resin and a preparation method of the main chain type benzoxazine resin.

Background

Along with the development of modern society, people have more and more harsh requirements on materials, namely aerospace, automobile and wind power industries, face the opportunities and challenges in the technical field of composite material waste recycling, so that the realization of recycling of composite material waste is beneficial to sustainable and sustainable development of industrial production processes, is also a necessary requirement for protecting environment and resources, and has important social significance.

With the development of emerging industries such as large airplanes, new energy sources, rail transit and the like in China, the application field of the thermosetting resin matrix composite material is continuously expanded, and the recycling problem of the thermosetting resin matrix composite material is more and more prominent. Many research institutions at home and abroad have proposed related problems, and research on recycling problems of the materials is carried out [ green recycling research of composite materials of Xin-Ningbo materials is carried out to obtain novel chemical materials [ J ] [ 2013 (2): 168-168 ].

At present, comprehensive treatment has become a new direction of composite material recycling technology, and mainly comprises two aspects: (1) The recycling and reuse of waste is considered in the design and manufacture. Such as manufacturing the blade by using a thermoplastic composite material, researching and using a bamboo fiber reinforced composite material, researching and using a bio-based adhesive to replace epoxy resin, and the like; new manufacturing techniques are studied to reduce the waste emissions in the manufacturing process, etc. (2) Integrates various processing technologies and realizes the full utilization of resources. At present, advanced foreign treatment technology tends to utilize other industrial bases, comprehensively uses the methods, fully utilizes the characteristics of wastes, simultaneously recovers energy and substances, and maximally realizes the recovery and utilization of the wastes. Such as cement kiln treatment technology, etc. [ Guo Jun ] composite material waste recovery technology at home and abroad and current state of development [ J ]. Innovative guide of science and technology, 2011 (33): 99-100 ]. The main research directions are roughly divided into two aspects: firstly, researching a new technology for treating non-regenerated thermosetting composite material waste; secondly, new renewable and degradable materials [ Duan Zhijun, duan Wangchun, zhang Ruiqing ] are developed, and the current situation of recycling composite materials at home and abroad [ J ]. Plastic industry, 2011,39 (1): 14-18 ].

For degradation recovery of thermosetting resins, many expert scholars at home and abroad have conducted related researches, the main methods include two kinds of physical methods and chemical methods, wherein the physical methods mainly adopt mechanical crushing recovery, the chemical methods mainly comprise pyrolysis methods and solvent methods [ Xu Pinglai, li Juan, li Xiaoqian ]. The Hou Xianglin team of the Shanxi coal formation institute utilizes coordinated unsaturated zinc ions to selectively break carbon-nitrogen bonds of the epoxy resin, so that the efficient degradation and recycling of the carbon fiber reinforced epoxy resin are realized; the method utilizes weakly coordinated aluminum ions to selectively break ester bonds, realizes that glass fiber reinforced unsaturated polyester resin is degraded and recycled [Deng T S,Liu Y,Cui X J,et al.Cleavage of C-N bonds in carbon fiber/epoxy resin composites.Green Chemistry,2015,17,2141-2145.].T. Iwaya and the like to react for 1 to 8 hours in diethylene glycol monomethyl ether and phenethyl alcohol solvent under the catalysis of K ₃PO₄ at the temperature of 190 to 350 ℃ to degrade unsaturated polyester, and the long glass fiber is recycled [Iwaya T,et al.Recycling of fiber reinforced plastics using depolymerization by solvothermal reaction with catalyst.J Mater Sci,2008,43(7):2452–2456.].

The waste of the thermosetting composite material is mainly treated by landfill and incineration, and the landfill method occupies land resources and causes soil damage. The burning does not cause land waste, but a large amount of toxic gas is generated in the burning, secondary pollution is caused, and potential and unknown risks exist at the same time [ chemical information and Ningbo material composite material green recycling research is developed [ J ]. Chemical novel material, 2013 (2): 168-168.].

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

The benzoxazine resin (BZ) is a novel thermosetting resin, is prepared from phenols, aldehydes and amine compounds through condensation reaction, is a material prepared from the benzoxazine resin through curing, has good heat resistance and flame retardance except the traditional phenolic resin, has low porosity due to the fact that no volatile micromolecules are released in the ring-opening curing process, almost does not exist in internal stress and cracks, is beneficial to processing and forming of finished products and maintaining the size of the products, and can be widely applied to various fields such as buildings, traffic, aviation, aerospace, electronics, ships, energy and the like [ Guo Jun ] as a waste recovery technology and development status quo [ J ]. Technological guide, 2011 (33): 99-100 ].

Meanwhile, benzoxazines still have some disadvantages, such as high curing temperature, generally reaching 200 ℃; the curing time is long; the benzoxazine resin obtained after traditional benzoxazine polymerization is brittle and has low mechanical property; the processing process is complicated, most benzoxazine monomers are solid, and the benzoxazine monomers are difficult to use as conveniently as liquid thermosetting resin prepolymer 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 drawbacks, using the flexible molecular design of benzoxazines, researchers have developed a benzoxazine of a novel structure, i.e. a synthetic monomer or its copolymer backbone contains a benzoxazine ring, called backbone-type benzoxazine (MCBP). The main chain benzoxazine monomer tends to crosslink to obtain excellent strength and flexibility, and the benzoxazine monomer can be dissolved in a solvent and can be processed in a molten state, and the material after heating and curing is still a thermosetting polymer. Because the main chain type benzoxazine resin has some advantages of thermosetting resin and thermoplastic resin, the main chain type benzoxazine resin has good application prospect, and can be used as electronic packaging, printed circuit boards, aviation and film materials. [ once bordure, zeng Bijun, yan Die, et al, preparation of low dielectric backbone benzoxazine resin, performance study [ J ]. Copper-clad plate information, 2016 (05): 31-36 ].

The crosslinked network structure of benzoxazine resin after curing is insoluble and infusible, and the application of the benzoxazine resin is greatly limited in recycling and degradability. How to recycle the cured benzoxazine is a very realistic problem. Under the guidance of national policy, the industrial recovery and reuse process of the thermosetting carbon fiber composite material waste with small energy consumption and good recovery effect is greatly developed, the recycling recovery and reuse of the composite material waste is realized, and the method has important significance for building a resource-saving, environment-friendly and harmonious society, responding to calls of national and foreign environmental protection, energy conservation and emission reduction and sustainable development [ Liu Jianshe, song Jinmei, peng Yugang, and the like ].

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides a main chain type benzoxazine resin, a composite curing resin containing the main chain type benzoxazine resin 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 curing substance containing the benzoxazine resin can be degraded at an acidic or high temperature, and after separation and recovery of degradation products, recycling of materials can be realized, thereby completing the invention.

One of the objects of the present invention is to provide a main chain benzoxazine resin which is a polymer, wherein the molecular chain of the polymer contains at least one of the repeating units represented by the formulas (I-1) to (I-3):

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

The main chain benzoxazine resin contains an acetal structure, so that the material can be endowed with acid sensitivity, degradation is realized under an acidic condition, recycling of the material is facilitated, and good environmental benefits are achieved. Further, 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 the 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 ends, one of which is a structure represented by one of the formulas (II-1) to (II-3) and the other of which is a structure represented by one of the 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 definition as 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), 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 selected from at least one of the polymers of formula (i-1) to formula (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 formulae (I-1) to (I-3), each R is independently selected from at least one of C2-C20 alkyl and its derivatives, C6-C20 aryl and its derivatives, C6-C20 alicyclic and its derivatives.

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

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

The second object of the present invention is to provide a method for preparing the main chain type benzoxazine resin according to one of the objects of the present invention, wherein the main chain type benzoxazine resin is obtained by reacting raw materials including bisphenol compounds containing spiro acetal structures, diamine compounds and aldehyde compounds.

Among them, the method can be performed using a solution method, a solvent-free method and a suspension method disclosed in the prior art, and a solution method is preferable.

In a preferred embodiment, the bisphenol compound having a spiro acetal structure is selected from at least one of pentaerythritol bis-parahydroxybenzaldehyde (p-SQ) represented by formula (IV-1), pentaerythritol bis-metahydroxybenzaldehyde (m-SQ) represented by formula (IV-2), pentaerythritol bis-orthohydroxybenzaldehyde (o-SQ) represented by formula (IV-3), and derivatives thereof.

In a preferred embodiment, the diamine compound is at least one selected from aliphatic diamine and its derivatives, aromatic diamine and its derivatives, alicyclic diamine and its derivatives.

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

In a still further preferred embodiment, the diamine compound is selected from at least one of aliphatic diamines of C2-C10 and derivatives thereof, aromatic diamines of C6-C10 and derivatives thereof, alicyclic diamines of C6-C10 and derivatives thereof.

For example, the diamine compound is at least one selected from ethylenediamine, butanediamine, hexamethylenediamine, 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 aqueous formaldehyde solutions, preferably paraformaldehyde.

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

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

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

Wherein the molar amount of the bisphenol compound having a spiro acetal structure is calculated based on the molar amount of phenolic hydroxyl groups therein, the molar amount of the diamine compound is calculated based on the molar amount of amine groups therein, and the molar amount of the aldehyde compound is calculated based on the molar amount of aldehyde groups therein.

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

Step 1, mixing the aldehyde compound, the bisphenol compound containing the spiro acetal structure, the diamine compound and 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, dimethyl sulfoxide, 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, dimethyl sulfoxide 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 from 80 to 150 ℃, preferably from 90 to 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 35 hours, preferably 20 to 30 hours, for example 15 hours, 16 hours, 17 hours, 18 hours, 19 hours, 20 hours, 21 hours, 22 hours, 23 hours, 24 hours, 25 hours, 26 hours, 27 hours, 28 hours, 29 hours, 30 hours, 31 hours, 32 hours, 33 hours, 34 hours or 35 hours.

In a preferred embodiment, in step 2, the post-treatment comprises alkali wash, water wash and solvent stripping treatment.

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

Wherein the alkali liquor can be at least one selected from alkaline aqueous solutions such as sodium hydroxide aqueous solution, potassium hydroxide aqueous solution and the like.

In a still further preferred embodiment, the solvent is removed by 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 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 is raised from 140 ℃ to 240 ℃, each 20 ℃ is provided with a temperature step, and each temperature step is reacted for 2 hours.

Specifically, 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 benzoxazine resin cured product can be degraded in an acid solution, preferably, the benzoxazine resin cured product is soaked in the acid solution and is degraded after being reacted for 8-48 hours, wherein the stronger the acidity is, the longer the time is, and the higher the chemical degradation degree of the cured product is.

Preferably, the acid used in the acidic solution is selected from organic acids (e.g., at least one of formic acid, acetic acid, trifluoromethanesulfonic 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 selected from at least one of 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-propanediol, 1, 2-propanediol, glycerol, ethylene glycol monomethyl ether, diethylene glycol, triethylene glycol, dipropylene glycol, furfuryl alcohol, tetrahydrofurfuryl alcohol; the ketone compound is at least one selected from 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 object of the present invention is to provide a bisphthalonitrile-based composite material comprising a main chain type benzoxazine resin and a bisphthalonitrile-based compound containing a spiroacetal structure, wherein the main chain type benzoxazine resin is selected from one of the main chain type benzoxazine resins of the present invention or a main chain type benzoxazine obtained by the two of the methods of the present invention.

Wherein the spiro acetal structure-containing bisphthalonitrile compound contains a spiro acetal structure, and the compound can adopt the spiro acetal structure-containing bisphthalonitrile compound disclosed in the prior art, for example, but not limited to, refer to patent CN112010833A and document "Ke Li,Hua Yin,Kun Yang,Pei Dai,Ling Han and Riwei Xu.Synthesis and properties of phthalonitrile-based resins containing spirocycle acetal.High Performance Polymers 2020",, and CN112010833A and the document are incorporated herein in their entirety.

The curing temperature of the bisphthalonitrile compounds containing only spiroacetal structures is relatively high, the highest curing temperature is higher than 250 ℃, and even can reach 300-400 ℃, for example, the highest curing temperature reaches 375 ℃ in the embodiment in patent CN 112010833A. However, the inventors have found through a lot of experiments that when a mixture of a bisphthalonitrile compound having a spiro acetal structure and a main chain type benzoxazine according to the present invention is cured, the presence of the main chain type benzoxazine can lower the curing temperature of the bisphthalonitrile compound having a spiro acetal structure in the mixture, and in particular, the mixture can be cured at a temperature lower than 250 ℃.

In addition, the spiroacetal structure is destroyed at a high temperature (for example, 250 ℃ and above), and when a bisphthalonitrile compound simply containing the spiroacetal structure is cured, the maximum curing temperature is significantly higher than 250 ℃, so that the spiroacetal bond in the compound is destroyed at a high temperature, and the obtained cured product loses degradability under an acidic condition. Therefore, the cured product of the bisphthalonitrile compound generally containing a spiroacetal structure cannot be degraded in acid.

In the invention, the inventor finds through a large number of experiments that by introducing the main chain type benzoxazine into the bisphenol phthalonitrile compound containing the spiro acetal structure, the curing temperature of the bisphenol phthalonitrile compound containing the spiro acetal structure is reduced, and particularly, the curing can be realized under the condition of being lower than 250 ℃, so that the spiro acetal bond in the bisphenol phthalonitrile compound containing the spiro acetal structure is not damaged, and the acid degradability of the bisphenol phthalonitrile compound containing the spiro acetal structure is maintained.

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

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

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

The fifth object of the present invention is to provide a bisphthalonitrile-based composite cured resin which is the ring-opened cured product of the fourth object of the present invention.

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

For example, the temperature is raised from 120 ℃ to 240 ℃ with a temperature gradient of each 20 ℃ and each temperature gradient is reacted for 2 hours to obtain a cured product.

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

Description of the inability of the spiroacetal structure-containing phthalonitrile-based cured resin to degrade: it is clear from the experiments and analyses made in the literature "Ke Li,Hua Yin,Kun Yang,Pei Dai,Ling Han and Riwei Xu.Synthesis and properties of phthalonitrile-based resins containing spirocycle acetal.High Performance Polymers 2020", that the phthalonitrile-based cured resin containing only the spiroacetal structure loses degradability because some reactions of the spiroacetal structure may occur during the high temperature curing process, resulting in the destruction of the spiroacetal structure to form other structures, which can be explained from FTIR (fig. 8 in the literature).

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

(1) The acetal structure is introduced into the main chain benzoxazine resin, so that the degradability of the resin can be endowed, and the main chain benzoxazine resin is favorable for recycling; (2) The acetal introduced into the main chain benzoxazine resin is spiro acetal, has certain rigidity, and gives better heat resistance to the benzoxazine resin in the curing process and heat resistance and rigidity to the cured resin; (3) The main chain type benzoxazine resin can reduce the curing temperature of the bisphthalonitrile compound containing an acetal structure; (4) The bisphthalonitrile-based composite cured 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 order. Fig. 17 to 32 show nuclear magnetic patterns of the main chain benzoxazines obtained in comparative example 2, example 1 and examples 8 to 21 in order.

Detailed Description

The present invention is described in detail below with reference to specific embodiments, and it should be noted that the following embodiments are only for further description of the present invention and should not be construed as limiting the scope of the present invention, and some insubstantial modifications and adjustments of the present invention by those skilled in the art from the present disclosure are still within the scope of the present invention. Unless otherwise specified, reagents and equipment used in the following examples are commercially available products.

Preparation of pentaerythritol Di-condensed m-hydroxy phthalonitrile refers to patent CN112010833A or literature "Ke Li,Hua Yin, Kun Yang,Pei Dai,Ling Han and Riwei Xu.Synthesis and properties of phthalonitrile-based resins containing spirocycle acetal.High Performance Polymers 2020".

The test methods employed in the examples and comparative examples:

FTIR: IS-5 Fourier infrared spectrometer, KBr tabletting method;

H-NMR: brukerAvance 400MHz at 25℃in deuterated chloroform; the invention adopts the integral area conversion of H in the group R and H in the hydroxyl end in the nuclear magnetic result to obtain possible n value.

DSC: TQ100, 10 ℃ per minute, nitrogen atmosphere.

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

Degradation degree = [1- (W1-W2)/W1 ] ×100%

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

Comparative example 1

According to the phenolic hydroxyl group: an amine group: aldehyde group = 1:1:2.1 (molar ratio) weighing the raw materials, and sequentially 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 into a 100mL three-necked flask, 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, then gradually heated to 95 ℃ and reacted for 10h. After the reaction was completed, the product was washed with aqueous sodium hydroxide (1M), filtered, washed with deionized water to neutrality, filtered, dried under vacuum to constant weight (50 ℃) and weighed with a yield of 75.2%. The bisphenol A-aniline benzoxazine resin is cured according to the temperature programming of 140,160,180 and 200 ℃, each temperature section is kept for 1 hour, and finally the temperature is reduced to room temperature, and the obtained cured product is used for the comparative example of subsequent chemical degradation; degradation experiments were performed under conditions of ethanol to water to acetic acid (0.1M) =4:1:1, and the products were found to not degrade. The molecular structure of the product is shown below.

Example 1

According to the phenolic hydroxyl group: an amine group: aldehyde=1:1:2 (molar ratio) raw materials were weighed, and 3.44g (0.01 mol) of pentaerythritol bis-parahydroxybenzaldehyde, 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 paraformaldehyde was added at one time; the reaction temperature was set at 115℃and the reaction was carried out for 24 hours. After the reaction was completed, the product was washed with aqueous sodium hydroxide (1M), filtered, washed with deionized water to neutrality, filtered, dried under vacuum to constant weight (50 ℃) and weighed with a yield of 50.1%. The molecular structure of the product is shown below.

Example 2

According to the phenolic hydroxyl group: an amine group: raw materials were weighed in the same manner 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: an amine group: raw materials are weighed according to the aldehyde group=1:1:2 (molar ratio), the synthesis process is the same as in example 1, except that a mixed solvent of DMF and n-butanol is selected as a solvent, DMF: n-butanol=1:3, and the yield is 53.5%.

Example 4

According to the phenolic hydroxyl group: an amine group: aldehyde=1:1.2:2 (molar ratio) the starting materials were weighed and the synthesis procedure was the same as in example 1 with a yield of 43.1%.

Example 5

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

Example 6

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

Example 7

The synthesis was identical to example 3, except that the reaction time was 12h and the yield was 35.3%.

Example 8

According to the phenolic hydroxyl group: an amine group: aldehyde=1:1:2 (molar ratio) raw materials were weighed, and 3.44g (0.01 mol) of pentaerythritol bis-parahydroxybenzaldehyde, 1.16g (0.01 mol) of hexamethylenediamine, 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 24 hours. After the reaction was completed, the product was washed with aqueous sodium hydroxide (1M), filtered, washed with deionized water to neutrality, filtered, dried under vacuum to constant weight (50 ℃) and weighed with a yield of 52.2%. The molecular structure of the product is shown below.

Example 9

According to the phenolic hydroxyl group: an amine group: aldehyde=1:1:2 (molar ratio) raw materials were weighed, and 3.44g (0.01 mol) of pentaerythritol bis-parahydroxybenzaldehyde, 0.88g (0.01 mol) of butanediamine, 1.20g (0.04 mol) of paraformaldehyde and 50mL of DMF were sequentially added to a 100mL three-necked flask, wherein paraformaldehyde was added at one time; the reaction temperature was set at 115℃and the reaction was carried out for 24 hours. After the reaction was completed, the product was washed with aqueous sodium bicarbonate (0.5M), filtered, washed with deionized water to neutrality, filtered, dried under vacuum to constant weight (50 ℃), and weighed to give a yield of 54.3%. The molecular structure of the product is shown below.

Example 10

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

Example 11

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

Example 12

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

Example 13

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

Example 14

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

The molecular structure of the product is shown below.

Example 15

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

Example 16

According to the phenolic hydroxyl group: an amine group: aldehyde=1:1:2 (molar ratio) raw materials were weighed, and 3.44g (0.01 mol) of pentaerythritol bis-m-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 paraformaldehyde was added at one time; the reaction temperature was set at 115℃and the reaction was carried out for 24 hours. After the reaction was completed, the product was washed with aqueous sodium bicarbonate (0.5M), filtered, washed with deionized water to neutrality, filtered, dried under vacuum to constant weight (50 ℃), and weighed to give a yield of 49.3%. The molecular structure of the product is shown below.

Example 17

The synthesis was the same as in example 16 except that 1.08g (0.01 mol) of p-phenylenediamine was used in place of decylenediamine, and the yield was 48.1%. The molecular structure of the product is shown below.

Example 18

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

Example 19

According to the phenolic hydroxyl group: an amine group: aldehyde=1:1:2 (molar ratio) raw materials were weighed, and 3.44g (0.01 mol) of pentaerythritol bis-ortho-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 paraformaldehyde was added 1 time; the reaction temperature was set at 115℃and the reaction was carried out for 24 hours. After the reaction was completed, the product was washed with aqueous sodium bicarbonate (0.5M), filtered, washed with deionized water to neutrality, filtered, dried under vacuum to constant weight (50 ℃), and weighed to give a yield of 47.1%. The molecular structure of the product is shown below.

Example 20

The synthesis was the same as in example 19 except that 1.08g (0.01 mol) of p-phenylenediamine was used in place of decylenediamine, and the yield was 38.1%. The molecular structure of the product is shown below.

Example 21

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

Comparative example 2

According to the phenolic hydroxyl group: an amine group: aldehyde=1:1:2.1 (molar ratio) raw materials are weighed, 50ml of DMF,3.44g (0.01 mol) of pentaerythritol bis-parahydroxybenzaldehyde and 1.83ml (0.02 mo 1) of aniline are sequentially added into a 100ml three-neck flask, and the mixture is stirred and mixed uniformly; 1.261g (0.042 mol) of paraformaldehyde is added into the three-neck flask for 2 to 4 times, the three-neck flask is firstly placed into 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 at constant temperature. After the reaction, the reaction product is washed with 1mol/L sodium hydroxide aqueous solution, filtered, washed with deionized water to neutrality, filtered, and dried under vacuum at 50 ℃ to constant weight.

EXAMPLE 22 degradation Property experiment of benzoxazine resin cured product

The degradation properties of the benzoxazine resin having an acetal structure are described below by taking the degradation of the cured product of pentaerythritol bis-parahydroxybenzaldehyde-butanediamine main chain benzoxazine resin as an example.

Pentaerythritol bis-parahydroxybenzaldehyde-butanediamine main chain benzoxazine resin (synthetic conditions are shown in example 9) is solidified, each 20 ℃ is a temperature gradient, each temperature gradient is reacted for 2 hours, and the temperature is increased from 140 ℃ to 220 ℃ to obtain a solidified product. And (3) putting the cured product into different solutions for heating degradation, filtering after degradation for a certain time, drying filter paper to constant weight, and testing the degradation degree. Degradation conditions and results are shown in table 1.

TABLE 1 degradation behavior of pentaerythritol Di-Paroxybenzaldehyde-butanediamine Main chain benzoxazine resin after curing

As can be seen from table 1 above, the cured resin cured with the main chain type benzoxazine resin according to the present invention has acid degradability. And the higher the degradation temperature, the longer the degradation time, the more acidic the acidic solution for degradation is, and the more thorough the degradation is.

EXAMPLE 23 thermal stability Property

The resins obtained in examples and comparative example 2 were each subjected to TGA test and the structures are shown in table 2 below.

Table 2: TGA data

Oxazine species	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 type benzoxazine, the main chain type benzoxazine of the present invention has more excellent thermal stability, and the analysis reasons may be that: the rigidity of the spiro structure can endow the benzoxazine with higher initial decomposition temperature, and the main chain type benzoxazine of the invention contains more spiro structures, so that the thermal stability of the benzoxazine is more excellent.

EXAMPLE 24 degradation Property of composite cured resin of benzoxazine resin and phthalonitrile Compound containing Spirocyclic acetal Structure

The main chain benzoxazine resin and pentaerythritol bis-m-hydroxyphthalonitrile are mixed according to the weight ratio shown in the table 2 to obtain a composite material, the composite material is subjected to ring-opening curing, each 20 ℃ is a temperature gradient, 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 heating degradation, filtering after degradation for a certain time, drying filter paper to constant weight, and testing the degradation degree of the filter paper. 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 to a degree exceeding the benzoxazine content thereof, indicating that the phthalonitrile resin was also degraded.

Experimental example product detection

(1) Detection of (p-SQ) -decanediamine Main-chain benzoxazine resin obtained in example 1:

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

The nuclear magnetic detection results are as follows: a proton peak Ha newly appearing at a chemical shift δ=5.42 ppm, which belongs to hydrogen on the intermediate carbon of the oxazine ring-O-CH ₂ -N-structure, and a proton peak Hg at a chemical shift δ=5.39 ppm; a proton peak Hb newly appearing at chemical shift δ=4.85 ppm, belonging to hydrogen on the intermediate carbon of the oxazine ring Ar-CH ₂ -N-structure; because of the oxazine ring, the chemical shift and cleavage of hydrogen on the benzene ring changes, and proton peaks Hi, hj both appear in the chemical shift delta=6.7-7.1 ppm interval; the chemical shift of c, d, e, f on the intermediate spiro structure is also changed from original 4.5ppm to 3.6ppm

4.9Ppm to 3.6ppm.1.30,1.55,2.71ppm of hydrogen belonging to the-CH ₂ -structure of decamethylene diamine. Some of its peaks were integrated in whole to give S _a:S_b:S_g:S_(c+d+e+f):S_i:S_j:S_k: =2:2:1:8:1:1:10, so that it was possible to determine that (p-SQ) -decamethylene diamine backbone benzoxazine was successfully synthesized, where n=7.1 (calculated from the ratio of the number of hydrogen atoms in methylene groups to the number of hydrogen atoms in terminal hydroxyl groups in decamethylene diamine being equal to the ratio with respect to the integrated area).

The DSC analysis shows that the first downward peak is a melting endotherm, which is relatively broad, and the melting peak temperature is about 150 ℃. The second upward peak is the oxazine's cure exotherm peak, and the (p-SQ) -decamethylene diamine backbone benzoxazine's cure temperature is about 250 ℃. At around 280 ℃, a second upward curing exotherm peak occurs.

(2) Detection of (p-SQ) -hexamethylenediamine Main-chain benzoxazine resin obtained in example 8

The infrared detection results are as follows: the flexible vibration peak of C-C on benzene ring is 1501cm ^-1, and the absorption vibration peak of-CH ₂ -in hexamethylenediamine is 1383cm ^-1. The C-O characteristic peak of the acetal is 1119cm ^-1, namely the C-O characteristic absorption peak of tertiary carbon connected with two O atoms in the acetal ring. The 1234cm ^-1 is the telescopic vibration peak of the C-O-C bond on the oxazine ring; an absorption vibration peak of the oxazine ring is arranged at 945cm ^-1; the expansion and contraction vibration peak of C-O-C on the acetal ring is 1078cm ^-1, and the vibration peak of C-N-C on the oxazine ring is 1164cm ^-1. It can be seen that there is an oxazine ring present. the-CH-asymmetric and symmetric telescopic vibration absorption peaks on the methylene-CH ₂ -in the acetal ring are observed at 2849 and 2931cm ^-1. A stretching vibration peak of-OH was observed at 3526cm ^-1, indicating that the oxazine was flanked by free hydroxyl groups of the acetal bisphenol. At the same time, the characteristic peak of para-substitution of benzene ring at 830cm ^-1 disappeared, and the characteristic peak of 1,2, 4-trisubstituted benzene ring appears at 819, 888cm ^-1. The surface successfully synthesizes the (p-SQ) -hexamethylenediamine type benzoxazine.

The nuclear magnetic detection results are as follows: at chemical shift δ=5.38 ppm is proton peak Ha, which is hydrogen on the intermediate carbon of the oxazine ring-O-CH ₂ -N-structure. Since no single proton peak at Hg is observed, it is judged that the proton peak possibly coincides with the proton peak of Ha, and the coincidence of the proton peaks can be judged by integral comparison. Shown at δ=4.83 ppm is proton peak Hb, which is hydrogen on the intermediate carbon of the oxazine ring Ar-CH ₂ -N-structure. Because of the oxazine ring formation, the chemical shift and cleavage of hydrogen on the benzene ring changes, and proton peaks Hh, hi both appear in the chemical shift δ=6.7-7.1 ppm interval. In addition, the chemical shift of c, d, e, f around the intermediate spiro structure also varies from 4.5ppm to 3.6ppm to 4.6 ppm. Proton peaks Hk belonging to hexamethylenediamine appear at 1.29,1.49,2.81 ppm. Peak area integration of the plot resulted in S _a:S_b:S_g:S_c+d+e+f:S_h:S_i:S_k =2:2:1:8:1:1:3, so successful synthesis of (p-SQ) -hexamethylenediamine backbone benzoxazine, where n=6.3, can be determined.

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

(3) Detection of (p-SQ) -butanediamine Main-chain benzoxazine resin obtained in example 9

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

The nuclear magnetic detection results are as follows: at chemical shift δ=5.64 ppm is proton peak Ha, which is hydrogen on the intermediate carbon of the oxazine ring-O-CH ₂ -N-structure. Shown at δ=4.85 ppm is proton peak Hb, which is hydrogen on the intermediate carbon of the oxazine ring Ar-CH ₂ -N-structure. Because of the oxazine ring formation, the chemical shift and cleavage of hydrogen on the benzene ring changes, and proton peaks Hi, hj both appear in the chemical shift δ=6.9-7.1 ppm interval. In addition, the chemical shift of c, d, e, f in the intermediate spiro structure was changed from 4.5ppm to 3.6ppm to 4.9ppm to 3.6ppm, and some proton peaks overlapped with Hb. The proton peak Hk belonging to butanediamine appears in the interval 1.0ppm to 2.7 ppm. Peak area integration of the plot resulted in S _a:S_b:S_g:S_c+d+e+f:S_i:S_j =2:2:1:8:1:1, thus a successful synthesis of (p-SQ) -butanediamine-backbone benzoxazine, where n=4.2, could be determined.

DSC shows that the first downward peak is the melting endotherm, the melting peak top temperature is about 150 ℃, and the peak is wide. The second upward peak is the oxazine curing exotherm peak with a peak top temperature of about 256 ℃.

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

The infrared detection results are as follows: the position 1501cm ^-1 is the C-C stretching vibration peak on benzene ring, and the position 1383cm ^-1 is the-CH ₂ -absorption vibration peak in ethylenediamine. The 1242cm ^-1 is a telescopic vibration peak of C-O-C on the oxazine ring; the C-O characteristic peak of the acetal is 1119cm ^-1, namely the C-O characteristic absorption peak of tertiary carbon connected with two O atoms in the acetal ring; an absorption vibration peak of the oxazine ring is arranged at 945cm ^-1; the expansion and contraction vibration peak of C-O-C on acetal is 1076cm ^-1, and the vibration peak of C-N-C on oxazine ring is 1168cm ^-1. It can be seen that an oxazine ring is present. At 2937 and 2849cm ^-1 are the-CH-asymmetric and symmetric telescopic vibration absorption peaks on the methylene-CH ₂ -in the acetal ring. In addition, a stretching vibration peak of-OH was observed at 3426cm ^-1, indicating that oxazine was flanked by free hydroxyl groups of acetal bisphenol.

The nuclear magnetic detection results are as follows: at chemical shift δ=5.37 ppm is proton peak Ha, which is hydrogen on the intermediate carbon of the oxazine ring-O-CH ₂ -N-structure. Since no single proton peak at Hg is observed, it is judged that the proton peak possibly coincides with the proton peak of Ha, and the coincidence of the proton peaks can be judged by integral comparison. Shown at δ=4.62 ppm is proton peak Hb, which is hydrogen on the intermediate carbon of the oxazine ring Ar-CH ₂ -N-structure. Because of the oxazine ring formation, the chemical shift and cleavage of hydrogen on the benzene ring changes, and proton peaks Hh, hi both appear in the chemical shift δ=6.7-7.1 ppm interval. In addition, the chemical shift of c, d, e, f around the intermediate spiro structure also varies from 4.5ppm to 3.6ppm to 4.9ppm to 3.6ppm. The proton peak Hk belonging to ethylenediamine appears at 2.82 ppm. Peak area integration of the plot resulted in S _a:S_b:S_g:S_c+d+e+f:S_h:S_i:S_k =2:2:1:8:1:1:2, thus allowing a determination that (p-SQ) -ethylenediamine backbone benzoxazine was successfully synthesized, where n=4.0.

The DSC analysis shows that the first downward peak is a melting endotherm, which is about 80℃and is probably due to the low molecular weight of the main chain diamine, and thus the melting point. The second upward peak is the oxazine curing exotherm peak with an initial cure temperature of about 225 c and a peak top temperature of about 277 c.

(5) Detection of (p-SQ) -octanediamine Main-chain benzoxazine resin obtained in example 11

The infrared detection results are as follows: the stretching vibration peak of C-C on benzene ring is shown at 1503cm ^-1, and the absorption vibration peak of-CH ₂ -in octanediamine is shown at 1383cm ^-1. The 1234cm ^-1 is the stretching vibration peak of C-O-C on oxazine ring; the C-O characteristic peak of the acetal is 1119cm ^-1, namely the C-O characteristic absorption peak of tertiary carbon connected with two O atoms in the acetal ring; an absorption vibration peak of the oxazine ring is arranged at 950cm ^-1; the expansion and contraction vibration peak of C-O-C on acetal is 1076cm ^-1, and the vibration peak of C-N-C on oxazine ring is 1166cm ^-1. It can be seen that an oxazine ring is present. At 2931 and 2849cm ^-1 are the-CH-asymmetric and symmetric telescopic vibration absorption peaks on the methylene-CH ₂ -in the acetal ring. In addition, a stretching vibration peak of-OH was observed at 3350cm ^-1, indicating that the oxazine ends were free hydroxyl groups of the acetal bisphenol.

The nuclear magnetic detection results are as follows: at chemical shift δ=5.38 ppm is proton peak Ha, which is hydrogen on the intermediate carbon of the oxazine ring-O-CH ₂ -N-structure. Shown at δ=4.85 ppm is proton peak Hb, which is hydrogen on the intermediate carbon of the oxazine ring Ar-CH ₂ -N-structure. Because of the oxazine ring formation, the chemical shift and cleavage of hydrogen on the benzene ring changes, and proton peaks Hi, hj both appear in the chemical shift δ=6.7-7.1 ppm interval. In addition, the chemical shift of c, d, e, f in the intermediate spiro structure was changed from 4.5ppm to 3.6ppm to 4.9ppm to 3.6ppm, and some proton peaks overlapped with Hb. Proton peaks Hk belonging to octanediamine occur in the interval 1.3ppm to 2.7 ppm. Peak area integration of the plot resulted in S _a:S_b:S_g:S_c+d+e+f:S_i:S_j =2:2:1:8:1:1, thus confirming successful synthesis of (p-SQ) -octanediamine backbone benzoxazine, where n=7.6.

DSC measurements show that the downward peak at 80℃is the melting peak of oxazine in the DSC plot. The upward peak is the exothermic curing peak of the oxazine, and the curing temperature of the oxazine is about 210 ℃. At around 251 c, a downward endothermic peak occurs, probably due to the decomposition of oxazine at high temperatures.

(6) Detection of (p-SQ) -1, 12-diaminododecane Main-chain benzoxazine obtained in example 12

The infrared detection results are as follows: the position 1504cm ^-1 is the stretching vibration peak of C-C on the benzene ring; the 1238cm ^-1 part is the expansion vibration peak of C-O-C on the oxazine ring; 1116cm ^-1 is the C-O characteristic peak of the acetal, namely the C-O characteristic absorption peak of tertiary carbon connected with two O atoms in the acetal ring; an absorption vibration peak of the oxazine ring is arranged at 918cm ^-1; the 1072 and 829cm ^-1 are the stretching vibration peaks of C-O-C on the acetal ring; in addition, the oscillation peak of C-N-C on the oxazine ring is also found at 8239 cm ^-1. 2924 and 2850cm ^-1 are the vibrational peaks of CH ₂、CH₃ carried on 1, 12-diaminododecane. It can be seen that an oxazine ring is present.

The nuclear magnetic detection results are as follows: at chemical shift δ=5.38 ppm is proton peak Ha, which is hydrogen on the intermediate carbon of oxazine ring-O-CH ₂ -N-structure, and proton peak at Hg coincides with Ha. Shown at δ=4.55 ppm is proton peak Hb, which is hydrogen on the intermediate carbon of the oxazine ring Ar-CH ₂ -N-structure. Because of the oxazine ring formation, the chemical shift and cleavage of hydrogen on the benzene ring changes, and proton peaks Hi, hj both appear in the chemical shift δ=6.7-7.2 ppm interval. In addition, the chemical shift of c, d, e, f around the intermediate spiro structure also varies from 4.5ppm to 3.6ppm to 4.9ppm to 3.6ppm. The proton peak Hk belonging to the diamine dodecane appears in the range of 1.3ppm to 2.7ppm, probably due to the large solubility, and the peak area ratio is slightly deviated, but the position where the peak appears is accurate. Peak area integration of the plot resulted in S _a:S_b:S_g:S_c+d+e+f:S_i:S_j =2:2:1:8:1:1, thus allowing a determination that (p-SQ) -1, 12-diaminododecane backbone-type benzoxazine was successfully synthesized, where n=4.5.

DSC measurements, in which a broader melting peak at 120℃is seen, there is an upward exotherm at 160 ℃. Two oxazine curing exotherm peaks appear at 236 ℃ and 278 ℃.

(7) Detection of (p-SQ) -4,4' -diaminodiphenylmethane backbone benzoxazine obtained in example 13

The infrared detection results are as follows: the position 1506cm ^-1 is a stretching vibration peak of C-C on the benzene ring; the 1233cm ^-1 part is the expansion vibration peak of C-O-C on the oxazine ring; the C-O characteristic peak of the acetal is 1114cm ^-1, namely the C-O characteristic absorption peak of tertiary carbon connected with two O atoms in the acetal ring; an absorption vibration peak of the oxazine ring is arranged at 938cm ^-1; 1077cm ^-1 is the stretching vibration peak of C-O-C on the acetal ring; 1170cm ^-1 is the C-N-C vibration peak of oxazine ring. The position 824cm ^-1 is a peak of para-position substituted benzene ring, and the peak is higher, compared with aliphatic main chain type oxazine, the peak is obviously improved, so that the oxazine main chain contains a 4,4' -diaminodiphenyl methane structure. At 2910 and 2837cm ^-1 is the vibrational peak of-CH ₂ -carried on 4,4' -diaminodiphenylmethane, the peak being smaller because of the short carbon chain. In addition, a stretching vibration peak of-OH was observed at 3426cm ^-1, indicating that oxazine was flanked by free hydroxyl groups of acetal bisphenol. It can be seen that an oxazine ring is present.

The nuclear magnetic detection results are as follows: at chemical shift δ=5.38 ppm is proton peak Ha, which is hydrogen on the intermediate carbon of oxazine ring-O-CH ₂ -N-structure, and proton peak at Hg coincides with Ha. Shown at δ=4.54 ppm is proton peak Hb, which is hydrogen on the intermediate carbon of the oxazine ring Ar-CH ₂ -N-structure. Because of the oxazine ring formation, the chemical shift and cleavage of hydrogen on the benzene ring changes, and proton peaks Hi, hj both appear in the chemical shift δ=6.7-7.2 ppm interval. In addition, the chemical shift of c, d, e, f around the intermediate spiro structure also varies from 4.5ppm to 3.6ppm to 4.9ppm to 3.6ppm. The proton peak Hk belonging to the methylene group on 4,4' -diaminodiphenylmethane appears at 3.83 ppm. Peak area integration of the plot resulted in S _a:S_b:S_g:S_c+d+e+f:S_i:S_j:S_k =2:2:1:8:1:1:2, thus allowing a determination that (p-SQ) -4,4' -diaminodiphenylmethane backbone benzoxazine was successfully synthesized, where n=14.

DSC shows that the first broad downward peak is the melting endotherm, around 110℃and probably because the backbone diamine is a mixture, thus melting point is low and broad. The second upward peak is the oxazine curing exotherm peak, which is at a curing temperature of about 263 ℃.

(8) Detection of (p-SQ) -diaminodiphenyl sulfone Main-chain benzoxazine resin obtained in example 14

The infrared detection results are as follows: the position 1501cm ^-1 is the C-C telescopic vibration peak on the benzene ring, and the position 1234cm ^-1 is the C-O-C telescopic vibration peak on the oxazine ring; the 948cm ^-1 is the absorption vibration peak of the oxazine ring; the 1083cm ^-1 is the C-O-C stretching vibration peak of acetal, and the 1160cm ^-1 is the C-N-C vibration peak of oxazine ring. It can be seen that an oxazine ring is present. At 1290cm ^-1 is the vibration peak of the sulfone. In addition, a stretching vibration peak of-OH was observed at 3400cm ^-1, indicating that oxazines were flanked by free hydroxyl groups of acetal bisphenol.

The nuclear magnetic detection results are as follows: at chemical shift δ=5.29 ppm is proton peak Ha, which is hydrogen on the intermediate carbon of the oxazine ring-O-CH ₂ -N-structure. Shown at δ=4.85 ppm is proton peak Hb, which is hydrogen on the intermediate carbon of the oxazine ring Ar-CH ₂ -N-structure. Because of the oxazine ring formation, the chemical shift and cleavage of hydrogen on the benzene ring changes, and proton peaks Hi, hj both appear in the chemical shift δ=6.7-7.1 ppm interval. In addition, the chemical shift of c, d, e, f in the intermediate spiro structure was changed from 4.5ppm to 3.6ppm to 4.9ppm to 3.6ppm, and some proton peaks overlapped with Hb. Proton peaks Hk and Hl belonging to diaminodiphenyl sulfone appear at 6.72ppm and 7.63ppm, respectively. Peak area integration of the plot resulted in S_a:S_b:S_g:S_c+d+e+f:S_i:S_j:S_k:S_l＝2:2:1:8:1:1:2∶2, thus confirming successful synthesis of the (p-SQ) -diaminodiphenyl sulfone backbone benzoxazine, where n=13.

DSC measurements, in which it can be seen that there is a downward melting peak at 93℃, there are two smaller upward peaks at 132 ℃ and 163 ℃, while the oxazine curing exotherm peak occurs at 302 ℃ high temperature. Since dioxydiphenyl sulfone is a curing agent with excellent heat resistance, the sulfur atom in the molecular structure is in the highest oxidation state, and the sulfonyl group tends to attract electrons on the benzene ring to make the benzene ring lack electrons, so that the whole diphenyl sulfone group is in the oxidation-resistant state. The curing temperature of the oxazine is significantly increased after the diaminodiphenyl sulfone is incorporated into the backbone.

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

The infrared detection results are as follows: the expansion vibration peak of C-C on benzene ring is 1501cm ^-1, and the absorption vibration peak of-CH ₂ -in 4,4' -methylenebis (2-methylcyclohexylamine) is 1378cm ^-1. 1452cm ^-1 is the characteristic peak of methyl groups in amines. The 1234cm ^-1 is the stretching vibration peak of C-O-C on oxazine ring; the C-O characteristic peak of the acetal is 1119cm ^-1, namely the C-O characteristic absorption peak of tertiary carbon connected with two O atoms in the acetal ring; an absorption vibration peak of the oxazine ring is arranged at 945cm ^-1; the expansion and contraction vibration peak of C-O-C on acetal is 1078cm ^-1, and the vibration peak of C-N-C on oxazine ring is 1164cm ^-1. It can be seen that an oxazine ring is present. At 2925 and 2847cm ^-1 are the-CH-asymmetric and symmetric telescopic vibration absorption peaks on the methylene-CH ₂ -in the acetal ring. In addition, a stretching vibration peak of-OH was observed at 3400cm ^-1, indicating that oxazines were flanked by free hydroxyl groups of acetal bisphenol. The characteristic peak of para-substitution of benzene ring is shown at 826cm ^-1.

The nuclear magnetic detection results are as follows: at chemical shift δ=5.42 ppm is proton peak Ha belonging to hydrogen on intermediate carbon of oxazine ring-O-CH ₂ -N-structure, and at 5.38ppm is proton peak at Hg. Shown at δ=4.86 ppm is proton peak Hb, which is hydrogen on the intermediate carbon of the oxazine ring Ar-CH ₂ -N-structure. Because of the oxazine ring formation, the chemical shift and cleavage of hydrogen on the benzene ring changes, and proton peaks Hi, hj both appear in the chemical shift δ=6.7-7.2 ppm interval. In addition, the chemical shift of c, d, e, f in the intermediate spiro structure was changed from 4.5ppm to 3.6ppm to 4.9ppm to 3.6ppm, and some proton peaks 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 2.36ppm, respectively. Peak area integration of the plot resulted in S_a:S_b:S_g:S_c+d+e+f:S_i:S_j:S_k:S_m＝2:2:1:8:1:1:2:3, thus confirming successful synthesis of (p-SQ) -4,4' -methylenebis (2-methylcyclohexylamine) backbone benzoxazine, where n=6.7.

DSC measurements show that there is a broad downward melting peak at 80℃and two upward smaller exothermic peaks at 120℃and 145 ℃. Is the exothermic peak of the oxazine cure at 240 ℃.

(10) Detection of (m-SQ) -decanediamine Main-chain benzoxazine resin obtained in example 16

The infrared detection results are as follows: the 1490cm ^-1 is the C-C stretching vibration peak of benzene ring, and the 1378cm ^-1 is the-CH ₂ -absorption vibration peak of decanediamine. The 1234cm ^-1 is the stretching vibration peak of C-O-C on oxazine ring; an absorption vibration peak of the oxazine ring is arranged at 950cm ^-1; the expansion and contraction vibration peak of C-O-C on acetal is 1078cm ^-1, and the vibration peak of C-N-C on oxazine ring is 1168cm ^-1. It can be seen that an oxazine ring is present. At 2931 and 2849cm ^-1 are the-CH-asymmetric and symmetric telescopic vibration absorption peaks on the methylene-CH ₂ -in the acetal ring. In addition, a stretching vibration peak of-OH was observed at 3400cm ^-1, indicating that oxazines were flanked by free hydroxyl groups of acetal bisphenol. Peaks appearing at 870 and 800cm ^-1 are characteristic peaks of asymmetric 1,2, 4-trisubstituted benzene rings, and C-H out-of-plane bending vibration peaks belonging to disubstitution between benzene rings also disappear at 887cm ^-1、756cm^-1 and 714cm ^-1.

The nuclear magnetic detection results are as follows: at chemical shift δ=5.68 ppm is proton peak Ha, which is hydrogen on the intermediate carbon of the oxazine ring-O-CH ₂ -N-structure. Shown at δ=4.86 ppm is proton peak Hb, which is hydrogen on the intermediate carbon of the oxazine ring Ar-CH ₂ -N-structure. Because of the oxazine ring, the chemical shift and cleavage of hydrogen on the benzene ring is changed, and the chemical shift of c, d, e, f on the intermediate spiro structure is changed from original 4.5ppm-3.6ppm to 4.9ppm-3.6ppm.1.30,1.66,2.72ppm of hydrogen belonging to the-CH ₂ -structure of decamethylene diamine. Peak area integration of the plot resulted in S _a:S_b:S_g:S_c+d+e+f:S_h =2:2:1:8:20, thus a successful synthesis of (m-SQ) -decamethylene diamine backbone benzoxazine, where n=5.8, could be determined.

DSC measurements show a broad downward melting peak at 127℃and an upward oxazine cure peak at 222 ℃.

(12) Detection of (m-SQ) -p-phenylenediamine main chain benzoxazine resin obtained in example 17

The infrared detection results are as follows: the position 1501cm ^-1 is the C-C stretching vibration peak on the benzene ring. The C-O characteristic peak of the acetal is 1109cm ^-1, namely the C-O characteristic absorption peak of tertiary carbon connected with two O atoms in the acetal ring. The 1234cm < -1 > is the telescopic vibration peak of C-O-C on the oxazine ring; an absorption vibration peak of the oxazine ring is arranged at 950cm ^-1; the expansion and contraction vibration peak of C-O-C on acetal is 1076cm ^-1, and the vibration peak of C-N-C on oxazine ring is 1164cm ^-1. It can be seen that an oxazine ring is present. At 2956 and 2844cm ^-1 are the-CH-asymmetric and symmetric telescopic vibration absorption peaks on the methylene-CH ₂ -in the acetal ring. In addition, a stretching vibration peak of-OH was observed at 3400cm ^-1, indicating that oxazines were flanked by free hydroxyl groups of acetal bisphenol. Peaks appearing at 881 and 821cm ^-1 are characteristic peaks of asymmetric 1,2, 4-trisubstituted benzene rings, and at 830cm ^-1 are characteristic peaks of para-substituted benzene rings, which indicates that the p-phenylenediamine has been successfully grafted. The C-H out-of-plane bending vibration peaks belonging to the inter-benzene ring disubstituted also disappeared from 887cm ^-1、756cm^-1 and 714cm ^-1.

The nuclear magnetic detection results are as follows: at chemical shift δ=5.41 ppm is proton peak Ha, which is hydrogen on the intermediate carbon of the oxazine ring-O-CH ₂ -N-structure. And the proton peak at Hg coincides with Ha. Shown at δ=4.52 ppm is proton peak Hb, which is hydrogen on the intermediate carbon of the oxazine ring Ar-CH ₂ -N-structure. Because of the oxazine ring, the chemical shift and cleavage of hydrogen on the benzene ring is changed, and the chemical shift of c, d, e, f on the intermediate spiro structure is changed from original 4.5ppm-3.6ppm to 4.9ppm-3.6ppm. Hi is the proton peak in p-phenylenediamine. Peak area integration of the plot resulted in S _a:S_b:S_g:S_c+d+e+f:si=2:2:1:8:4, thus confirming successful synthesis of (m-SQ) -p-phenylenediamine backbone benzoxazines, where n=7.1.

DSC measurements show that there is a broad melting peak at 77 ℃. A plateau appears at 120 ℃ to 144 ℃, presumably to reach the rubber plateau, and oxazine has fluidity. Two curing peaks appear at 186 ℃ and 234 ℃.

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

The infrared detection results are as follows: the C-O characteristic peak of the acetal is 1109cm ^-1, namely the C-O characteristic absorption peak of tertiary carbon connected with two O atoms in the acetal ring. The absorption vibration peak of-CH ₂ -in 4,4' -methylenebis (2-methylcyclohexylamine) is shown at 1383cm ^-1. 1459cm ^-1 is the characteristic peak of methyl groups in amines. The 1235cm ^-1 part is the expansion vibration peak of C-O-C on the oxazine ring; an absorption vibration peak of the oxazine ring is arranged at 945cm ^-1; the expansion and contraction vibration peak of C-O-C on acetal is 1078cm ^-1, and the vibration peak of C-N-C on oxazine ring is 1168cm ^-1. It can be seen that an oxazine ring is present. At 2950 and 2844cm ^-1 are the-CH-asymmetric and symmetric telescopic vibration absorption peaks on the methylene-CH ₂ -in the acetal ring. In addition, a stretching vibration peak of-OH was observed at 3400cm ^-1, indicating that oxazines were flanked by free hydroxyl groups of acetal bisphenol. The peaks appearing at 880 and 819cm ^-1 are characteristic peaks of asymmetric 1,2, 4-trisubstituted benzene rings, and the C-H out-of-plane bending vibration peaks belonging to the disubstitution between benzene rings also vanish from 887cm ^-1、 756cm^-1 and 714cm ^-1.

The nuclear magnetic detection results are as follows: at chemical shift δ=5.42 ppm is proton peak Ha, which is hydrogen on the intermediate carbon of oxazine ring-O-CH ₂ -N-structure, and proton peak at Hg coincides with Ha. Shown at δ=4.83 ppm is proton peak Hb, which is hydrogen on the intermediate carbon of the oxazine ring Ar-CH ₂ -N-structure. Because of the oxazine ring formation, the chemical shift and cleavage of hydrogen on the benzene ring changes, and proton peaks Hi, hj both appear in the chemical shift δ=6.7-7.2 ppm interval. In addition, the chemical shift of c, d, e, f in the intermediate spiro structure was changed from 4.5ppm to 3.6ppm to 4.9ppm to 3.6ppm, and some proton peaks 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. The peak area integration was performed on the graph to obtain S_a:S_b:S_g:S_c+d+e+f:S_i:S_j:S_k:S_m＝2:2:1:8:1:1:2:3, that theoretically had consistent hydrogen ratios at each position. Since the oxazine peak was observed and the ratio was substantially correct, it was determined that (m-SQ) -4,4' -methylenebis (2-methylcyclohexylamine) main chain benzoxazine was successfully synthesized, where n=5.9.

DSC measurements show that there is a downward melting peak at 83℃and two smaller upward curing peaks at 114℃and 130℃in the DSC plot, presumably by disruption of the cyclic amine ring structure, and a larger upward oxazine curing peak at 198 ℃.

(14) Detection of (o-SQ) -decanediamine Main-chain benzoxazine resin obtained in example 19

The infrared detection results are as follows: the position 1501cm ^-1 is the C-C stretching vibration peak on benzene ring, and the position 1383cm ^-1 is the-CH ₂ -absorption vibration peak in decanediamine. The 1234cm ^-1 is the stretching vibration peak of C-O-C on oxazine ring; the C-O characteristic peak of the acetal is 1111cm ^-1, namely the C-O characteristic absorption peak of tertiary carbon connected with two O atoms in the acetal ring; an absorption vibration peak of the oxazine ring is arranged at 945cm ^-1; the expansion and contraction vibration peak of C-O-C on acetal is 1078cm ^-1, and the vibration peak of C-N-C on oxazine ring is 1164cm ^-1. It can be seen that an oxazine ring is present. At 2931 and 2849cm ^-1 are the-CH-asymmetric and symmetric telescopic vibration absorption peaks on the methylene-CH ₂ -in the acetal ring. In addition, a stretching vibration peak of-OH was observed at 3400cm ^-1, indicating that oxazines were flanked by free hydroxyl groups of acetal bisphenol. Peaks at 810, 760 and 701cm ^-1 are characteristic peaks of continuous 1,2, 3-trisubstituted benzene rings.

The nuclear magnetic detection results are as follows: at chemical shift δ=5.74 ppm is proton peak Ha, hydrogen on intermediate carbon belonging to oxazine ring-O-CH ₂ -N-structure, δ=5.72 ppm is proton peak Hg. Shown at δ=4.86 ppm is proton peak Hb, which is hydrogen on the intermediate carbon of the oxazine ring Ar-CH ₂ -N-structure. Because the oxazine ring is generated, the chemical shift and cleavage of hydrogen on the benzene ring are changed, the chemical shift of c, d, e, f on the middle spiro structure is changed from 4.5ppm-3.6ppm to 4.9ppm-3.6ppm, and proton peaks Hi and Hj are both in the chemical shift delta=6.7-7.1 ppm interval. 1.26,1.47,2.62ppm of hydrogen belonging to the-CH ₂ -structure of decamethylene diamine. Peak area integration of the plot resulted in S _a:S_b:S_g:S_c+d+e+f:S_i:S_j:S_h =2:2:1:8:1:1:20, thus allowing a determination that (o-SQ) -decamethylene diamine backbone benzoxazine was successfully synthesized, where n=5.9.

DSC measurements show that there is a downward melting peak at 70℃and upward oxazine cure peaks at 165℃and 226℃in the DSC plot.

(15) Detection of (o-SQ) -p-phenylenediamine main chain benzoxazine resin obtained in example 20

The infrared detection results are as follows: the C-C stretching vibration peak on benzene ring is at 1503cm ^-1. The 1234cm ^-1 is the stretching vibration peak of C-O-C on oxazine ring; 1109cm ^-1 is the C-O characteristic peak of the acetal, namely the C-O characteristic absorption peak of tertiary carbon connected with two O atoms in the acetal ring; an absorption vibration peak of the oxazine ring is arranged at 945cm ^-1; the expansion and contraction vibration peak of C-O-C on acetal is 1078cm ^-1, and the vibration peak of C-N-C on oxazine ring is 1164cm ^-1. It can be seen that an oxazine ring is present. At 2950 and 2849cm ^-1 are the-CH-asymmetric and symmetric telescopic vibration absorption peaks on the methylene-CH ₂ -in the acetal ring. In addition, a stretching vibration peak of-OH was observed at 3401cm ^-1, indicating that oxazine was flanked by free hydroxyl groups of acetal bisphenol. Peaks at 810, 760 and 701cm ^-1 are characteristic peaks of continuous 1,2, 3-trisubstituted benzene rings. The characteristic peak of para-substitution of benzene ring is also at 810cm ^-1, and the two peaks are slightly overlapped. Indicating that p-phenylenediamine has been successfully grafted.

The nuclear magnetic detection results are as follows: at chemical shift δ=5.30 ppm is proton peak Ha, which is hydrogen on the intermediate carbon of the oxazine ring-O-CH ₂ -N-structure. And the proton peak at Hg coincides with Ha. Shown at δ=4.52 ppm is proton peak Hb, which is hydrogen on the intermediate carbon of the oxazine ring Ar-CH ₂ -N-structure. Because of the oxazine ring, the chemical shift and cleavage of hydrogen on the benzene ring is changed, and the chemical shift of c, d, e, f on the intermediate spiro structure is changed from original 4.5ppm-3.6ppm to 4.9ppm-3.6ppm. Hi is the proton peak in p-phenylenediamine. Peak area integration of the plot resulted in S _a:S_b:S_g:S_c+d+e+f:si=2:2:1:8:4, thus confirming successful synthesis of (o-SQ) -p-phenylenediamine backbone benzoxazines, where n=7.4.

DSC measurements show a downward melting peak at 55deg.C, a small and insignificant upward curing peak at 156 deg.C, and a significant upward exothermic oxazine curing peak at 255 deg.C.

(16) Detection of (o-SQ) -4,4' -methylenebis (2-methylcyclohexylamine) backbone benzoxazine obtained in example 21

The infrared detection results are as follows: the position 1501cm ^-1 is the C-C stretching vibration peak on the benzene ring. The absorption vibration peak of-CH ₂ -in 4,4' -methylenebis (2-methylcyclohexylamine) is shown at 1383cm ^-1. 1452cm ^-1 is the characteristic peak of methyl groups in amines. The 1237cm ^-1 part is the expansion vibration peak of C-O-C on the oxazine ring; the C-O characteristic peak of the acetal is 1114cm ^-1, namely the C-O characteristic absorption peak of tertiary carbon connected with two O atoms in the acetal ring; an absorption vibration peak of the oxazine ring is arranged at 945cm ^-1; the expansion and contraction vibration peak of C-O-C on acetal is 1078cm ^-1, and the vibration peak of C-N-C on oxazine ring is 1164cm ^-1. It can be seen that an oxazine ring is present. At 2920 and 2849cm ^-1 are the-CH-asymmetric and symmetric telescopic vibration absorption peaks on the methylene-CH ₂ -in the acetal ring. In addition, a stretching vibration peak of-OH was observed at 3400cm ^-1, indicating that oxazines were flanked by free hydroxyl groups of acetal bisphenol. Peaks at 813, 760 and 703cm ^-1 are characteristic peaks of continuous 1,2, 3-trisubstituted benzene rings.

The nuclear magnetic detection results are as follows: at chemical shift δ=5.70 ppm is proton peak Ha belonging to hydrogen on intermediate carbon of oxazine ring-O-CH ₂ -N-structure, and proton peak at Hg coincides with Ha. Shown at δ=4.58 ppm is proton peak Hb, which is hydrogen on the intermediate carbon of the oxazine ring Ar-CH ₂ -N-structure. Because of the oxazine ring formation, the chemical shift and cleavage of hydrogen on the benzene ring changes, and proton peaks Hi, hj both appear in the chemical shift δ=6.7-7.2 ppm interval. In addition, the chemical shift of c, d, e, f around the intermediate spiro structure also varies from 4.5ppm to 3.6ppm to 4.9ppm to 3.6ppm. Proton peaks Hk and Hm belonging to methylene and methyl groups on 4,4' -methylenebis (2-methylcyclohexylamine) appear at 3.86ppm and 2.20ppm, respectively. The peak area integration of the plot gives Sa: sb: sg+d+e+f: si: sj: sk: sm=2:2:1:8:1:1:2:3, and thus it can be determined that (o-SQ) -4,4' -methylenebis (2-methylcyclohexylamine) backbone benzoxazine was successfully synthesized, where n=6.3.

DSC measurements show that there is a downward melting exotherm at 112℃and two upward oxazine cure peaks at 152℃and 202 ℃. There is a downward peak at 257 deg.c, presumably when the oxazine is decomposed.

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

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

The nuclear magnetic detection results are as follows: a proton peak Ha newly appearing at the chemical shift δ=4.60 ppm, belonging to hydrogen on the intermediate carbon of the oxazine ring N-C structure; the chemical shift δ=5.38 ppm belongs to proton peaks Hb and Hc, and the corresponding peak area S _b+c:S_a =3:2 also satisfies the corresponding hydrogen ratio; the chemical shift of d, e, f, g on the middle spiro structure also varies from 4.5ppm to 3.6ppm to 4.9ppm to 3.6ppm, and the chemical shifts of the two hydrogens overlap. Some of its peaks are integrated overall S _a:S_b+c:S_d:S_e∶S_f:S_g∶S_{(h+i+j+k+l+m)} = 2:3:1:1:1:1:8, consistent with the theoretical ratio of hydrogen at each position. It was confirmed that (p-SQ) -aniline-type benzoxazine was successfully synthesized (δ=7.29 ppm solvent peak of CDCl ₃).

When DSC is performed, the first downward peak is a melting endothermic peak, and the melting peak top temperature is about 155 ℃. The second upward peak is the exothermic curing peak of the oxazine, the initial curing temperature of the (p-SQ) -aniline-type benzoxazine is 180 ℃, and the peak top temperature is about 227 ℃. At around 290 c, a downward endothermic peak begins to appear, probably due to the decomposition of oxazine at high temperatures.

The invention has been described in detail in connection with the specific embodiments and exemplary examples thereof, but such description is not to be construed as limiting the invention. It will be understood by those skilled in the art that various equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its embodiments without departing from the spirit and scope of the present invention, and these fall within the scope of the present invention. The scope of the invention is defined by the appended claims.

Claims

1. A bisphthalonitrile-based composite material, comprising a main chain benzoxazine resin and a bisphthalonitrile compound containing a spirocyclic acetal structure, wherein the main chain benzoxazine resin accounts for 10 to 50 wt % and the bisphthalonitrile compound containing a spirocyclic acetal structure accounts for 50 to 90 wt % based on 100 wt % of the total weight of the bisphthalonitrile-based composite material;

The main chain benzoxazine resin is selected from at least one of the polymers represented by formula (i-1) to formula (i-3):

Formula (i-1)

Formula (i-2)

Formula (i-3)

In formula (i-1) to formula (i-3), n is 2 to 20, and each R is independently selected from at least one of an aliphatic group, an alicyclic group, and a phenyl group.

2. The diphthalonitrile-based composite material according to claim 1, characterized in that, in formulas (i-1) to (i-3), each R is independently selected from at least one of a C2 to C20 alkyl group, a phenyl group, and a cyclohexyl group.

3. The diphthalonitrile-based composite material according to claim 2, characterized in that, in formulas (i-1) to (i-3), each R is independently selected from at least one of a C2 to C10 alkyl group, a phenyl group, and a cyclohexyl group.

4. The bisphthalonitrile-based composite material according to claim 1, characterized in that the preparation method of the main chain benzoxazine resin comprises: reacting raw materials including a bisphenol compound containing a spirocyclic acetal structure, a diamine compound and an aldehyde compound to obtain the main chain benzoxazine resin.

5. The bis(o-phthalonitrile)-based composite material according to claim 4, characterized in that:

The aldehyde compound is selected from paraformaldehyde and/or formaldehyde solution.

6. The bis(o-phthalonitrile)-based composite material according to claim 5, characterized in that:

The aldehyde compound is selected from paraformaldehyde.

7. The bisphthalonitrile-based composite material according to claim 4, characterized in that the molar ratio of the bisphenol compound containing the spiroacetal structure, the diamine compound and the aldehyde compound is 1:1:(2~5).

8. The bisphthalonitrile-based composite material according to claim 7, characterized in that the molar ratio of the bisphenol compound containing the spiroacetal structure, the diamine compound and the aldehyde compound is 1:1:(2-3).

9. The bis(o-phthalonitrile)-based composite material according to any one of claims 4 to 8, wherein the method comprises the following steps:

Step 1, mixing the aldehyde compound, the bisphenol compound containing a spiroacetal structure, the diamine compound and a solvent, and stirring;

Step 2, heating to carry out reaction, and performing post-treatment after the reaction is completed to obtain the main chain type benzoxazine resin.

10. The bis(o-phthalonitrile)-based composite material according to claim 9, characterized in that:

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

In step 2, the reaction temperature is 80-150° C.; and/or,

In step 2, the reaction is carried out for 15 to 35 hours; and/or,

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

11. The bis(o-phthalonitrile)-based composite material according to claim 10, characterized in that:

In step 2, the reaction temperature is 90-130° C.; and/or,

In step 2, the reaction is carried out for 20 to 30 hours.

12. A bisphthalonitrile-based composite cured resin, which is a ring-opening cured product of the bisphthalonitrile-based composite material according to any one of claims 1 to 11, wherein the ring-opening curing is carried out at 120 to 240°C.

13 . The diphthalonitrile-based composite curing resin according to claim 12 , wherein the temperature is increased from 120° C. to 240° C., with each temperature gradient of 10° C. to 30° C., and each temperature gradient is reacted for 1 to 3 hours.