CN115433333B

CN115433333B - Benzoxazine resin with erythritol acetal structure

Info

Publication number: CN115433333B
Application number: CN202110616478.7A
Authority: CN
Inventors: 徐日炜; 杨慧丽; 孟庆旭; 韩翎; 张韬毅; 祝桂香; 张伟; 许宁
Original assignee: Beijing University of Chemical Technology
Current assignee: Sinopec Beijing Chemical Research Institute Co ltd; China Petroleum and Chemical Corp; Beijing University of Chemical Technology
Priority date: 2021-06-02
Filing date: 2021-06-02
Publication date: 2023-12-15
Anticipated expiration: 2041-06-02
Also published as: CN115433333A

Abstract

The invention discloses a novel chemically degradable benzoxazine resin, which is prepared by utilizing phenol source containing erythritol acetal structure, amine and aldehyde condensation reaction, and resin or condensate is obtained by curing, or a composite material prepared from benzoxazine containing erythritol acetal structure can be completely degraded under acidic condition, after separation and recovery of degradation products, recycling of the material can be realized, and the problem that the benzoxazine containing erythritol acetal structure cannot be degraded due to insoluble cross-linked network structure after the benzoxazine is cured is solved.

Description

Benzoxazine resin with erythritol acetal structure

Technical Field

The invention relates to the fields of benzoxazine resin synthesis, benzoxazine resin recycling and the like, in particular to benzoxazine resin with an erythritol acetal structure.

Background

Benzoxazine is a novel thermosetting resin with a nitrogen-oxygen-containing heterocyclic structure, and is obtained by a Mannich condensation reaction of an amine compound, a phenol compound and formaldehyde. Under the condition of adding a curing agent or heating, the benzoxazine is subjected to ring-opening curing to form a nitrogen-containing cross-linked network structure, so that the benzoxazine is also called ring-opening phenolic resin.

The benzoxazine resin is used as a novel phenolic resin, inherits the advantages of the traditional phenolic resin, such as good mechanical property, heat resistance, flame retardant property, dielectric property, low price of raw materials and the like, and meanwhile, the benzoxazine forms a crosslinked three-dimensional network structure through ring-opening polymerization, no small molecules are released in the curing process, and the size of the product is close to zero shrinkage and has no microcracks. In addition, because the benzoxazine has flexible molecular design, by utilizing the combination of amine and phenolic compounds with various structures and introducing groups such as cross-linking, heat resistance, flame retardance and the like, the benzoxazine resin with good thermal stability, mechanical property and electrical property can be prepared, and is widely applied to the fields of electronic packaging, advanced composite material matrix resin, ablation resistant materials and the like.

Meanwhile, benzoxazines have some disadvantages, such as high curing temperature, generally reaching 200 ℃, and long curing time; 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 defects, by utilizing the flexible molecular design of the benzoxazine, researchers develop a benzoxazine with a novel structure, namely, a synthetic monomer or a copolymer thereof contains a benzoxazine ring, and the benzoxazine monomer can be dissolved in a solvent and can be processed in a molten state, and a material after heating and solidifying is still a thermosetting polymer. The benzoxazine resin has the advantages of thermosetting resin and thermoplastic resin, has good application prospect, and can be used as electronic packaging, printed circuit boards, aviation and film materials.

The crosslinked network structure of benzoxazine resins after curing is insoluble, which greatly limits their use 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 are realized, and the method has important significance for building a resource-saving and environment-friendly harmonious society and responding to calls of domestic and foreign environmental protection, energy conservation and emission reduction and sustainable development.

Disclosure of Invention

In order to overcome the above problems, the present inventors have conducted intensive studies on benzoxazines, have explored various chemical structures over several years, and have found that the introduction of an erythritol acetal structure into a benzoxazine can achieve complete degradation of a resin, a cured product or a composite material prepared from a benzoxazine containing an erythritol acetal structure under acidic conditions, and after separation and recovery of degradation products, recycling of the material can be achieved, wherein the prepared benzoxazine containing an erythritol acetal structure has excellent rigidity, thereby completing the present invention.

In particular, it is an object of the present invention to provide the following aspects:

in a first aspect, there is provided a benzoxazine of erythritol acetal structure comprising the unit (I) shown below:

wherein R is an aliphatic group, an alicyclic group, an aromatic group, or derivatives of the aliphatic group, the alicyclic group and the aromatic group.

In a second aspect, there is provided a process for the preparation of benzoxazines of erythritol acetal structure, the process comprising: and heating reflux reaction of phenols, amines and aldehydes in an organic solution to obtain the benzoxazine.

In a third aspect, there is provided a method of preparing a resin from a benzoxazine of erythritol acetal structure, the method comprising: the benzoxazine containing erythritol acetal structure is cured.

The invention has the beneficial effects that:

(1) The benzoxazine with the erythritol acetal structure provided by the invention contains the erythritol acetal structure, so that the benzoxazine is endowed with excellent heat resistance and rigidity, the resin, the cured product or the composite material prepared from the benzoxazine is completely degraded under the acidic condition, the recycling of the material is realized, and the problem that the benzoxazine cannot be degraded due to insoluble cross-linked network structure after curing is solved.

(2) The benzoxazine with the erythritol acetal structure provided by the invention has excellent rigidity.

(3) The benzoxazine resin with the erythritol acetal structure provided by the invention has the advantages of simple preparation method and environment friendliness. The prepared benzoxazine has high mechanical properties and meets the industrial requirements.

Drawings

FIG. 1 shows an infrared spectrogram of example 1;

FIG. 2 shows a nuclear magnetic hydrogen spectrum of example 1;

FIG. 3 shows a DSC graph of example 1;

FIG. 4 shows an infrared spectrogram of example 2;

FIG. 5 shows a DSC graph of example 2;

FIG. 6 shows an infrared spectrogram of example 3;

FIG. 7 shows a DSC graph of example 3;

FIG. 8 shows an infrared spectrogram of example 4;

FIG. 9 shows an infrared spectrum of example 5;

FIG. 10 shows an infrared spectrum of example 6;

FIG. 11 shows an infrared spectrogram of example 7;

FIG. 12 shows an infrared spectrogram of example 8;

FIG. 13 shows a nuclear magnetic hydrogen spectrum of example 8;

FIG. 14 shows a DSC plot of example 8;

fig. 15 shows an infrared spectrogram of example 9;

FIG. 16 shows a DSC graph of example 9;

FIG. 17 shows a DSC plot of example 10;

fig. 18 shows an infrared spectrogram of example 11;

FIG. 19 shows a nuclear magnetic resonance hydrogen spectrum of example 11;

FIG. 20 shows a DSC plot of example 11;

fig. 21 shows an infrared spectrogram of example 12;

FIG. 22 shows a DSC plot of example 12;

FIG. 23 shows a DSC graph of example 13;

FIG. 24 shows an infrared spectrum of example 14;

fig. 25 shows an infrared spectrogram of example 16;

FIG. 26 shows an infrared spectrum of example 18;

fig. 27 shows a DSC profile of comparative example 1.

Detailed Description

In a first aspect of the present invention, there is provided a benzoxazine of erythritol acetal structure comprising the unit (I) shown below:

In a preferred embodiment, the benzoxazine contains free hydroxyl groups, including any one or several of the units (II) - (v) as shown below:

in each unit, R is aliphatic group, alicyclic group and aromatic group or derivatives of the aliphatic group, the alicyclic group and the aromatic group, n is more than or equal to 1 and less than or equal to 30, and n is an integer.

In a preferred embodiment, the benzoxazine is a benzoxazine terminated with an anilino group comprising unit (vi) as shown below:

wherein R is aliphatic, alicyclic or aromatic group or derivative of aliphatic, alicyclic or aromatic group, n is more than or equal to 1 and less than or equal to 30, and n is an integer.

In a preferred embodiment, the benzoxazine is an anilino group terminated benzoxazine comprising any one or several of the units (vii) to (x) as shown below:

In a preferred embodiment, the benzoxazine is erythritol bis-p-hydroxybenzaldehyde-aniline benzoxazine having the following structural formula:

in a preferred embodiment, the benzoxazine is erythritol bis-p-hydroxybenzaldehyde-cyclohexylamine type benzoxazine, and the structural formula of the benzoxazine is shown as follows:

in a preferred embodiment, the benzoxazine is erythritol bis-p-hydroxybenzaldehyde-n-butylamine type benzoxazine, and the structural formula is shown as follows:

in a second aspect of the present invention, there is provided a process for the preparation of benzoxazines of erythritol acetal structure, said process being a solution process, comprising in particular: and heating reflux reaction of phenols, amines and aldehydes in an organic solution to obtain the benzoxazine.

In the invention, the solution method has the advantages of low system viscosity, uniform mixing, easy temperature control and the like compared with other methods such as a suspension method, and has higher yield. Studies have shown that reactions in different solvents can have an effect on the benzoxazine monomer yield, e.g., dimers or multimers can result in a decrease in the benzoxazine monomer content and thus in purity.

According to the present invention, in order to sufficiently dissolve the reactant in the organic solvent without causing side reaction, the organic solvent is preferably any one or more selected from dioxane, methanol, ethanol, dioxane, N-methylpyrrolidone, chloroform, toluene, N-dimethylformamide, more preferably N, N-dimethylformamide.

According to the invention, the phenols are bisphenols containing erythritol acetal structures, such as: erythritol bis-condensed para-hydroxybenzaldehyde (p-sq, chemical formula 1), erythritol bis-condensed meta-hydroxybenzaldehyde (m-sq, chemical formula 2), erythritol bis-condensed ortho-hydroxybenzaldehyde (o-sq, chemical formula 3), erythritol bis-condensed vanillin (v-sq, chemical formula 4), erythritol bis-condensed isovanillin (i-sq, chemical formula 5).

The inventor discovers that resin or compound prepared from benzoxazine containing erythritol acetal structure can be degraded under acidic condition, and can realize recycling of materials after separation, is very environment-friendly, and particularly has excellent heat resistance and rigidity when the benzoxazine prepared from erythritol acetal structure required by benzoxazine is provided by bisphenol containing erythritol acetal structure.

According to the invention, the amine comprises aliphatic amine such as butanediamine, 1, 5-pentanediamine, n-butane, cyclohexane, aromatic amine such as 4-aminobiphenyl, 4' -diaminodiphenylmethane, 2, 4-diaminotoluene, aniline, alicyclic amine such as isophorone diamine, 4-diaminodicyclohexylmethane, 1, 3-cyclohexanediamine, preferably any one or combination of butanediamine, n-butane, cyclohexane, 4' -diaminodiphenylmethane, 4' -diaminodicyclohexylmethane.

In the present invention, the aldehyde is preferably paraformaldehyde or an aqueous formaldehyde solution.

In the invention, bisphenol and primary amine are difunctional compounds, and can form compounds with high polymerization degree and long molecular chain structure and thermosetting property. The traditional method uses bisphenol monoamine or monophenol diamine as raw materials, the prepared benzoxazine resin has low molecular weight, and a cross-linked network formed during high-temperature curing has shorter molecular chain and smaller molecular free volume, so that the prepared cured product has poor flexibility and poor dielectric property.

In the invention, the benzoxazine prepared by taking bisphenol containing erythritol acetal structure as a raw material has excellent thermosetting property and can be completely degraded.

According to the invention, the molar ratio of phenolic hydroxyl groups in phenols, amine groups in amines and aldehyde functional groups in aldehydes is 1: (0.1-5): (0.5 to 8), preferably 1: (0.5-3): (1 to 5), more preferably 1: (1-2): (2.0 to 2.4).

Optionally, phenol is also added during the reaction, so that the rigidity of the benzoxazine can be reduced to a certain extent, the excessive rigidity is avoided, and the performance of the benzoxazine is reduced.

Wherein the molar ratio of phenols to phenol is 1: (1.5-3), e.g., 1:2.

In a preferred embodiment, phenols, amines and aldehydes are directly mixed with the organic solution and subjected to a temperature-rising reflux reaction.

At this time, the reaction temperature is 70 to 150 ℃, preferably 90 to 130 ℃, more preferably 100 to 120 ℃, for example 115 ℃; the reaction time is 10 to 36 hours, preferably 16 to 30 hours, more preferably 20 to 26 hours, for example 24 hours.

In another preferred embodiment, phenols and amines are dissolved in an organic solvent, and then aldehydes are added in batches, for example 3 to 5 times, to carry out a temperature-rising reflux reaction.

At this time, the reaction temperature is 60 to 150 ℃, preferably 90 to 120 ℃, more preferably 90 to 100 ℃, for example 95 ℃; the reaction time is 3 to 20 hours, preferably 6 to 15 hours, more preferably 9 to 12 hours, for example 10 hours.

In the present invention, the addition order of the reactants is different, and there is a difference in the optimal reaction temperature and reaction time for preparing benzoxazine containing erythritol acetal structure. In the reaction process, the reaction temperature and the reaction time can influence the structure of reaction products, the reaction temperature is too high or too low, and the reaction time is too long or too short, so that side reactions can be generated, and the reaction system is homogeneous in the reaction temperature and the reaction time range, so that high-quality benzoxazine can be obtained.

In the invention, after the reaction is finished, the benzoxazine is obtained by washing, filtering and drying a reaction product.

Wherein the washing includes alkali washing and water washing, and alkali washing is preferably performed by using a strong alkali aqueous solution, such as a sodium hydroxide aqueous solution.

In a third aspect of the present invention, there is provided a process for preparing a resin from a benzoxazine of erythritol acetal structure, the process comprising: the benzoxazine containing erythritol acetal structure is cured.

Wherein the curing temperature is 80-280 ℃, preferably 100-240 ℃, more preferably 140-220 ℃; the curing time is 6 to 16 hours, preferably 8 to 14 hours, more preferably 10 to 12 hours.

According to a preferred embodiment, the curing is a stepwise elevated temperature, one temperature step at each 15-20 ℃, each temperature step reacting for 1-2 hours.

The inventors have found that if an isothermal curing regime is used, the curing reaction can be carried out at a lower temperature, but longer curing times are required, whereas at higher temperatures the reaction time is shorter. When the curing reaction is carried out at a lower temperature, the curing reaction is gentle, a dense network cured product can be obtained, but the reactive groups are frozen in the later period of the curing reaction, the curing reaction is incomplete, and the glass transition temperature after the curing is lower. If the curing is carried out at a higher temperature, the reaction speed is severe, so that larger internal stress can be generated, more defects exist and the mechanical property is poor. When the step heating solidification mode is adopted to replace isothermal solidification, the defects can be overcome.

In the invention, the benzoxazine resin containing the erythritol acetal structure or the cured product prepared from the benzoxazine containing the erythritol acetal structure can be completely dissolved in an acidic solution, and has great application potential in recycling and degradability.

When degrading, the resin or the solidified matter prepared by benzoxazine containing erythritol acetal structure is soaked in acid solution for 8-48 hours.

According to the present invention, the acidic solution is not limited to any one organic acid such as formic acid, acetic acid, trifluoromethanesulfonic acid, trichloroacetic acid, or inorganic acid such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid.

According to the invention, the acidic solution is a mixture of an organic acid or an inorganic acid with a polar solvent comprising water, alcohol compounds such as ethanol, methanol, isopropanol, butanol, isobutanol, phenethyl alcohol, benzyl alcohol, ethylene glycol, butylene glycol, 1, 3-propanediol, 1, 2-propanediol, glycerol, diethylene glycol, triethylene glycol, dipropylene glycol, furfuryl alcohol, tetrahydrofurfuryl alcohol; ketones such as butanone, cyclohexanone; ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, tetrahydrofuran, 1, 4-dioxane; amides such as N, N-dimethylformamide, dimethyl sulfoxide, sulfolane, N-methylpyrrolidone, morpholine, N-methylmorpholine.

Examples

The invention is further described below by means of specific examples, which are however only exemplary and do not constitute any limitation on the scope of protection of the invention.

Example 1

Into a 50ml three-necked flask, 1.65g (0.005 mol) of erythritol parahydroxybenzaldehyde, 0.44g (0.005 mol) of butanediamine, 0.60g (0.02 mol) of paraformaldehyde and 20mL of N, N-Dimethylformamide (DMF) were charged, and the reflux reaction temperature was set at 115℃to conduct the reaction for 24 hours. After the reaction is finished, removing a solvent DMF from the obtained product by using a rotary evaporator, washing the reaction product by using 0.5M sodium bicarbonate aqueous solution, filtering, washing to neutrality by using deionized water, filtering, and drying at 50 ℃ to obtain the final product erythritol bis-parahydroxybenzaldehyde-butanediamine benzoxazine containing free hydroxyl and containing a unit II, wherein R is butanediamine, and the final product erythritol bis-parahydroxybenzaldehyde-butanediamine benzoxazine is called BPED for short.

Fig. 1 shows BPED infrared spectra. Wherein: 1501cm ^-1 Is characterized in that the position is a C-C telescopic vibration peak on benzene ring, 1389cm ^-1 Is butanediamine-CH ₂ Absorption vibration peak. 1219cm ^-1 The position is a telescopic vibration peak of a C-O-C bond on an oxazine ring; 1054cm ^-1 The C-O characteristic peak of the acetal is the C-O bond characteristic absorption peak of tertiary carbon connected with two O atoms on the acetal ring; 974cm ^-1 The absorption vibration peak of the oxazine ring is positioned; 1083cm ^-1 The position is a telescopic vibration peak of a C-O-C bond on an acetal ring; 1154cm ^-1 The vibration peak of the C-N-C bond on the oxazine ring is also shown, and the oxazine ring exists. At 3386cm ^-1 The stretching vibration peak of-OH can be observed, and the two ends of oxazine on the surface are the free hydroxyl groups of acetal bisphenol, which initially indicates that BPED is successfully synthesized.

FIG. 2 shows a BPED nuclear magnetic hydrogen spectrum. Wherein: a proton peak Ha newly appearing at the chemical shift δ=5.39 ppm, belonging to hydrogen on the intermediate carbon of the oxazine ring N-C structure; the chemical shift δ=4.85 ppm is the proton peak Hb, the chemical shift of d, e, f, g on the intermediate spiro structure varies from 4.27ppm-3.87ppm to 4.26ppm-3.45ppm, and the chemical shifts of the two hydrogens overlap. The peak area integration was performed in accordance with the theoretical hydrogen ratio at the above position, and it was confirmed that BPED was successfully synthesized (CDCl at δ=7.29 ppm) ₃ Solvent peak) of (c).

FIG. 3 shows a DSC curve of BPED, which shows that the curing peak temperature of BPED is 191 ℃.

Example 2

Benzoxazines were prepared in a similar manner as example 1, except that: the reactants added were 1.65g (0.005 mol) erythritol bis-parahydroxybenzaldehyde, 0.99g (0.005 mol) 4,4' -diaminodiphenylmethane, 0.60g (0.02 mol) paraformaldehyde and 20 mM DMF. The prepared benzoxazine is the main chain benzoxazine of erythritol bis-condensed p-hydroxybenzaldehyde-4, 4' -diaminodiphenylmethane, which contains free hydroxyl and contains a unit II, wherein R is 4, 4-diaminodiphenylmethane, and is called BPMD for short.

Fig. 4 shows a BPMD infrared spectrogram. Wherein: 1513cm ^-1 Is characterized by C-C telescopic vibration peaks on benzene ring, 2973 and 2888cm ^-1 Is the-CH in DDM ₂ Absorption vibration peak. 1231cm ^-1 The position is a telescopic vibration peak of a C-O-C bond on an oxazine ring; 1050cm ^-1 The C-O characteristic peak of the acetal is the C-O bond characteristic absorption peak of tertiary carbon connected with two O atoms on the acetal ring; 974cm ^-1 The absorption vibration peak of the oxazine ring is positioned; 1090cm ^-1 The position is a telescopic vibration peak of a C-O-C bond on an acetal ring; 1167cm ^-1 The vibration peak of the C-N-C bond on the oxazine ring is also shown, and the oxazine ring exists. At 3380cm ^-1 The stretching vibration peak of-OH can be observed, and the two ends of the oxazine on the surface are the free hydroxyl groups of acetal bisphenol, which initially indicates that BPMD is successfully synthesized.

Fig. 5 shows a DSC curve of BPMD, and shows that the melting peak temperature of BPMD is 148 ℃ and the curing peak temperature is 240 ℃.

Example 3

Benzoxazines were prepared in a similar manner as example 1, except that: the reactants added were 3.30g (0.01 mol) erythritol bis-parahydroxybenzaldehyde, 2.10g (0.01 mol) 4,4' -diaminodicyclohexylmethane, 1.2g (0.04 mol) paraformaldehyde and 50ml dmf. The prepared benzoxazine is the main chain benzoxazine of erythritol bis-condensed p-hydroxybenzaldehyde-4, 4 '-diamino dicyclohexylmethane, which contains free hydroxyl and contains a unit II, wherein R is 4,4' -diamino dicyclohexylmethyl, and is called BPHD for short.

Wherein the yield of the obtained reaction was 90.6%.

Fig. 6 shows a BPHD infrared spectrum. Wherein: 1502cm ^-1 The position is a C-C telescopic vibration peak on benzene ring, 1379cm ^-1 Is the-CH in PACM ₂ Absorption vibration peak. 1234cm ^-1 The position is a telescopic vibration peak of a C-O-C bond on an oxazine ring; 974cm ^-1 The absorption vibration peak of the oxazine ring is positioned; 1096cm ^-1 The position is a telescopic vibration peak of a C-O-C bond on an acetal ring; 1152cm ^-1 The vibration peak of the C-N-C bond on the oxazine ring is also shown, and the oxazine ring exists. At 3416cm ^-1 The stretching vibration peak of-OH can be observed, and the two ends of oxazine on the surface are free hydroxyl groups of acetal bisphenol, which initially indicates that BPHD is successfully synthesized.

Fig. 7 shows a DSC profile of BPHD, and the cure peak temperature of BPHD is 228 ℃.

Example 4

Benzoxazines were prepared in a similar manner as example 1, except that: the reactants added were 1.65g (0.005 mol) erythritol bis-m-hydroxybenzaldehyde, 0.44g (0.005 mol) butanediamine, 0.60g (0.02 mol) paraformaldehyde and 20 mM DMF. The prepared benzoxazine is an erythritol bis-condensed m-hydroxybenzaldehyde-butanediamine main chain type benzoxazine containing free hydroxyl and containing a unit III, wherein R is butanediamine, and the main chain type benzoxazine is BMED for short.

Fig. 8 shows a BMED infrared spectrum. Wherein: 1243cm ^-1 The position is a telescopic vibration peak of a C-O-C bond on an oxazine ring; 973cm ^-1 The absorption vibration peak of the oxazine ring is positioned; 1172cm ^-1 The vibration peak of the C-N-C bond on the oxazine ring is also shown, and the oxazine ring exists. At 3403cm ^-1 The stretching vibration peak of-OH can be observed, and the two ends of oxazine on the surface are the free hydroxyl groups of acetal bisphenol, which initially shows that BMED is successfully synthesized.

Example 5

Benzoxazines were prepared in a similar manner as example 1, except that: the reactants added were 1.65g (0.005 mol) erythritol bis-m-hydroxybenzaldehyde, 0.99g (0.005 mol) 4,4' -diaminodiphenylmethane, 0.60g (0.02 mol) paraformaldehyde and 20 mM DMF. The prepared benzoxazine is the main chain type benzoxazine of erythritol bis-m-hydroxybenzaldehyde-4, 4 '-diaminodiphenylmethane, which contains free hydroxyl and comprises a unit III, wherein R is 4,4' -diaminodiphenylmethane, and the unit is BMMD for short.

Fig. 9 shows a BMMD infrared spectrogram. Wherein: 1231cm ^-1 The position is a telescopic vibration peak of a C-O-C bond on an oxazine ring; 974cm ^-1 The absorption vibration peak of the oxazine ring is positioned; 1167cm ^-1 The vibration peak of the C-N-C bond on the oxazine ring is also shown, and the oxazine ring exists. At 3380cm ^-1 The stretching vibration peak of-OH can be observed, and the two ends of the oxazine on the surface are the free hydroxyl groups of acetal bisphenol, which initially shows that BMMD is successfully synthesized.

Example 6

Benzoxazines were prepared in a similar manner as example 1, except that: the reactants added were 1.95g (0.005 mol) erythritol bis-isovanillin, 0.44g (0.005 mol) butanediamine, 0.60g (0.02 mol) paraformaldehyde and 20 mM DMF. The prepared benzoxazine is erythritol biscondensed isovanillin-butanediamine main chain benzoxazine containing free hydroxyl and containing a unit V, wherein R is butanediamine, and the unit V is BIED for short.

Fig. 10 shows a BIED infrared spectrum. Wherein: 1219cm ^-1 The position is a telescopic vibration peak of a C-O-C bond on an oxazine ring; 968cm ^-1 The absorption vibration peak of the oxazine ring is positioned; 1163cm ^-1 The vibration peak of the C-N-C bond on the oxazine ring is also shown, and the oxazine ring exists. At 3416cm ^-1 The stretching vibration peak of-OH can be observed, and the two ends of oxazine on the surface are the free hydroxyl groups of acetal bisphenol, which initially indicates that BIED is successfully synthesized.

Example 7

Benzoxazines were prepared in a similar manner as example 1, except that: the reactants added were 1.95g (0.005 mol) erythritol bis-isovanillin, 0.99g (0.005 mol) 4,4' -diaminodiphenylmethane, 0.60g (0.02 mol) paraformaldehyde and 20 mM DMF. The prepared benzoxazine is the erythritol bis-isovanillin-4, 4 '-diaminodiphenylmethane main chain benzoxazine containing free hydroxyl and containing a unit V, wherein R is 4,4' -diaminodiphenylmethane, and is abbreviated as: BIMD.

Fig. 11 shows a BIMD infrared spectrum. Wherein: 1249cm ^-1 The position is a telescopic vibration peak of a C-O-C bond on an oxazine ring; 970cm ^-1 The absorption vibration peak of the oxazine ring is positioned; 1165cm ^-1 The vibration peak of the C-N-C bond on the oxazine ring is also shown, and the oxazine ring exists. At 3420cm ^-1 The stretching vibration peak of-OH can be observed, and the two ends of the oxazine on the surface are the free hydroxyl groups of acetal bisphenol, which initially indicates that BIMD is successfully synthesized.

Example 8

Benzoxazines were prepared in a similar manner as example 1, except that: the reactants added were 6.60g (0.02 mol) erythritol bis-parahydroxybenzaldehyde, 0.88g (0.01 mol) butanediamine, 1.86g (0.02 mol) aniline, 2.40g (0.08 mol) paraformaldehyde and 50 mM DMF. The prepared benzoxazine is a main chain type benzoxazine capped by anilino groups, and comprises erythritol bis-parahydroxybenzaldehyde-butanediamine aniline with butanediamine groups serving as units VI and R, and is BPEA for short.

Fig. 12 shows a BPEA infrared spectrum. Wherein: 1281cm ^-1 The position is a telescopic vibration peak of a C-O-C bond on an oxazine ring; 979cm ^-1 The absorption vibration peak of the oxazine ring is positioned; 1158cm ^-1 The vibration peak of the C-N-C bond on the oxazine ring is also shown, and the oxazine ring exists. 760 and 695cm ^-1 The characteristic peak of the monosubstituted benzene ring indicates that the aniline is blocked, and preliminary indicates that BPEA is successfully synthesized.

Fig. 13 shows BPEA nuclear magnetic hydrogen spectra. Proton peaks at chemical shifts δ=5.35 and 5.03ppm are terminal oxazine ring-O-CH, respectively ₂ -N-structure and Ar-CH ₂ -hydrogen on the intermediate carbon of the N-structure. With reference to FIG. 9, it can be explained that BPEA was successfully synthesized

Fig. 14 shows a BPEA DSC curve, and it can be seen that the first downward peak is a melting endotherm, and the melting peak top temperature is about 80 ℃. The second upward peak is the oxazine curing exotherm peak, the BPEA initial cure temperature is 145 ℃, and the peak top temperature is around 230 ℃.

Example 9

Benzoxazines were prepared in a similar manner as example 1, except that: the reactants added were 6.60g (0.02 mol) erythritol bis-parahydroxybenzaldehyde, 1.98g (0.01 mol) 4,4' -diaminodiphenylmethane, 1.86g (0.02 mol) aniline, 2.40g (0.08 mol) paraformaldehyde and 50 mM DMF. The prepared benzoxazine is a main chain type benzoxazine which is blocked by an aniline group and comprises an erythritol bis-condensed p-hydroxybenzaldehyde-4, 4 '-diaminodiphenyl methane aniline with a unit VI and R being 4,4' -diaminodiphenyl methane, and is abbreviated as BPMA.

Fig. 15 shows a BPMA infrared spectrum. Wherein: 1281cm ^-1 The position is a telescopic vibration peak of a C-O-C bond on an oxazine ring; 979cm ^-1 The absorption vibration peak of the oxazine ring is positioned; 1158cm ^-1 The vibration peak of the C-N-C bond on the oxazine ring is also shown, and the oxazine ring exists. 760 and 695cm ^-1 The characteristic peak of the monosubstituted benzene ring indicates that the aniline is blocked, and preliminary indicates that BPMA is successfully synthesized.

Fig. 16 shows a DSC curve of BPMA, from which the melting peak temperature is 114 ℃ and the curing peak temperature is 192 ℃.

Example 10

Benzoxazines were prepared in a similar manner as example 1, except that: the reactants added were 6.60g (0.02 mol) erythritol bis-parahydroxybenzaldehyde, 2.10g (0.01 mol) 4,4' -diaminodicyclohexylmethane, 1.86g (0.02 mol) aniline, 2.40g (0.08 mol) paraformaldehyde and 50ml LDMF. The prepared benzoxazine is a main chain type benzoxazine capped by anilino groups, and comprises erythritol bis-condensed p-hydroxybenzaldehyde-4, 4 '-diamino dicyclohexyl methane aniline with a unit VI and R being 4,4' -diamino dicyclohexyl methyl, and BPHA is short for short.

Fig. 17 shows a DSC curve of BPHA, and it is found that the melting peak temperature of BPHA is 94 ℃ and the curing peak temperature is 200 ℃.

Example 11

Benzoxazines were prepared in a similar manner as example 1, except that: the reactants added were 3.30g (0.01 mol) erythritol bis-parahydroxybenzaldehyde, 0.88g (0.01 mol) butanediamine, 0.94g (0.01 mol) phenol, 1.20g (0.04 mol) paraformaldehyde and 20 mM DMF. The prepared benzoxazine is a main chain type benzoxazine which is blocked by phenol groups and comprises a unit VII, wherein R is butanediamine, and the main chain type benzoxazine is formed by blocking erythritol bis-parahydroxybenzaldehyde-butanediamine phenol, and is called BPEF for short.

Fig. 18 shows a BPEF infrared spectrum. Wherein: 1493cm ^-1 Is characterized in that the position is a C-C telescopic vibration peak on benzene ring, 1387cm ^-1 Is butanediamine-CH ₂ Absorption vibration peak. 1259cm ^-1 The position is a telescopic vibration peak of a C-O-C bond on an oxazine ring; 1096cm ^-1 The C-O characteristic peak of the acetal is the C-O bond characteristic absorption peak of tertiary carbon connected with two O atoms on the acetal ring; 974cm ^-1 The absorption vibration peak of the oxazine ring is positioned; 1152cm ^-1 The vibration peak of the C-N-C bond on the oxazine ring is also shown, and the oxazine ring exists. Only at 757cm ^-1 Characteristic peaks of benzene rings appear, which indicate phenol end capping, and preliminary indicates that BPEF is successfully synthesized.

Fig. 19 shows BPEF nuclear magnetic hydrogen spectra. Proton peaks at chemical shifts δ=5.35 and 4.81ppm are terminal oxazine ring-O-CH, respectively ₂ -N-structure and Ar-CH ₂ -hydrogen on the intermediate carbon of the N-structure. The successful synthesis of BPEF is described with reference to fig. 13.

Fig. 20 shows a DSC curve of BPEF, and shows that the melting peak temperature of BPEF is 79 ℃ and the curing peak temperature is 225 ℃.

Example 12

Benzoxazines were prepared in a similar manner as example 1, except that: the reactants added were 3.30g (0.01 mol) erythritol bis-parahydroxybenzaldehyde, 3.97g (0.02 mol) 4,4' -diaminodiphenylmethane, 0.94g (0.01 mol) phenol, 1.20g (0.04 mol) paraformaldehyde and 20 mM DMF. The prepared benzoxazine is a main chain type benzoxazine which is blocked by phenol groups and comprises a unit VII, wherein R is erythritol bis-condensed parahydroxybenzaldehyde-4, 4' -diaminodiphenylmethane phenol, and the unit is BPMF for short.

Fig. 21 shows a BPMF infrared spectrum. Wherein: 1513cm ^-1 Is a benzene ringThe stretching vibration peak of C-C. 1228cm ^-1 The position is a telescopic vibration peak of a C-O-C bond on an oxazine ring; 1095cm ^-1 The C-O characteristic peak of the acetal is the C-O bond characteristic absorption peak of tertiary carbon connected with two O atoms on the acetal ring; 972cm ^-1 The absorption vibration peak of the oxazine ring is positioned; 1152cm ^-1 The vibration peak of the C-N-C bond on the oxazine ring is also shown, and the oxazine ring exists. Only at 756cm ^-1 Characteristic peaks of benzene rings appear, which indicate phenol end capping, and preliminary can indicate successful synthesis of BPMF.

Fig. 22 shows a DSC curve of BPMF, from which the melting peak temperature of BPMF was 117 ℃ and the curing peak temperature was 223 ℃.

Example 13

Benzoxazines were prepared in a similar manner as example 1, except that: the reactants added were 3.30g (0.01 mol) erythritol bis-parahydroxybenzaldehyde, 4.20g (0.02 mol) 4,4' -diaminodicyclohexylmethane, 1.88g (0.02 mol) phenol, 2.40g (0.08 mol) paraformaldehyde and 50 mM DMF. The prepared benzoxazine is a main chain type benzoxazine which is blocked by phenol groups and contains a unit VII, wherein R is erythritol bis-condensed parahydroxybenzaldehyde-4, 4' -diamino dicyclohexylmethane phenol, and the unit is BPHF for short.

FIG. 23 shows a DSC curve of BPHF, which shows a cure peak temperature of 224 ℃.

Example 14

Benzoxazines were prepared in a similar manner as example 1, except that: the reactants added were 3.30g (0.01 mol) of erythritol bis-m-hydroxybenzaldehyde, 3.97g (0.02 mol) of 4,4' -diaminodiphenylmethane, 0.94g (0.01 mol) of phenol, 1.20g (0.04 mol) of paraformaldehyde and 20 mM DMF. The prepared benzoxazine is a main chain type benzoxazine which is blocked by phenol groups and comprises units VIII, erythritol bis-m-hydroxybenzaldehyde-4, 4 '-diaminodiphenyl methane phenol with R being 4,4' -diaminodiphenyl methane, and BMMF for short.

Fig. 24 shows BMMF infrared spectra. Wherein: 1513cm ^-1 The stretching vibration peak of C-C on benzene ring. 1228cm ^-1 The position is a telescopic vibration peak of a C-O-C bond on an oxazine ring; 1092cm ^-1 The C-O characteristic peak of the acetal is the C-O bond characteristic absorption peak of tertiary carbon connected with two O atoms on the acetal ring; 970cm ^-1 The absorption vibration peak of the oxazine ring is positioned; 1177cm ^-1 The vibration peak of the C-N-C bond on the oxazine ring is also shown, and the oxazine ring exists. Only at 748cm ^-1 Characteristic peaks of benzene rings appear, which indicate phenol end capping, and preliminary indicates that BMMF is successfully synthesized.

Example 15

Benzoxazines were prepared in a similar manner as example 1, except that: the reactants added were 3.30g (0.01 mol) erythritol bis-ortho-hydroxybenzaldehyde, 3.97g (0.02 mol) 4,4' -diaminodiphenylmethane, 1.88g (0.02 mol) phenol, 2.40g (0.08 mol) paraformaldehyde and 50 mM DMF. The prepared benzoxazine is a main chain type benzoxazine which is blocked by phenol groups and contains an erythritol bis-o-hydroxybenzaldehyde-4, 4 '-diaminodiphenyl methane phenol with a unit IX and R being 4,4' -diaminodiphenyl methane, and is called BOMF for short.

Example 16

Benzoxazines were prepared in a similar manner as example 1, except that: the reactants added were 3.90g (0.01 mol) of erythritol bis-vanillin, 3.97g (0.02 mol) of 4,4' -diaminodiphenylmethane, 1.88g (0.02 mol) of phenol, 2.40g (0.08 mol) of paraformaldehyde and 50 mM DMF. The prepared benzoxazine is a main chain type benzoxazine which is blocked by phenol groups and comprises erythritol bis-vanillin-4, 4 '-diaminodiphenylmethane phenol with a unit X and R being 4,4' -diaminodiphenylmethane, and is abbreviated as BVMF.

Fig. 25 shows BVMF infrared spectra. Wherein: 1513cm ^-1 The stretching vibration peak of C-C on benzene ring. 1228cm ^-1 The position is a telescopic vibration peak of a C-O-C bond on an oxazine ring; 1101cm ^-1 The C-O characteristic peak of the acetal is the C-O bond characteristic absorption peak of tertiary carbon connected with two O atoms on the acetal ring; 974cm ^-1 The absorption vibration peak of the oxazine ring is positioned; 1151cm ^-1 The vibration peak of the C-N-C bond on the oxazine ring is also shown to be that the oxazine ringExists. Only at 757cm ^-1 Characteristic peaks of benzene rings appear, which indicate phenol end capping, and preliminary indicate that BVMF is successfully synthesized.

Example 17

Benzoxazines were prepared in a similar manner as example 1, except that: 1.65g (0.005 mol) of erythritol bis-ortho-hydroxybenzaldehyde, 0.44g (0.005 mol) of butanediamine, 0.60g (0.02 mol) of paraformaldehyde and 20 mM DMF are added. The prepared benzoxazine is erythritol bis-ortho-hydroxybenzaldehyde-butanediamine main chain benzoxazine containing free hydroxyl and containing a unit IV and R being butanediamine, and is called BOED for short.

Example 18

Benzoxazines were prepared in a similar manner as example 1, except that: the reactants added were 3.30g (0.01 mol) erythritol bis-ortho-hydroxybenzaldehyde, 0.88g (0.01 mol) butanediamine, 0.94g (0.01 mol) phenol, 1.20g (0.04 mol) paraformaldehyde and 20 mM DMF. The prepared benzoxazine is a main chain type benzoxazine which is blocked by phenol groups and comprises units IX and erythritol bis-o-hydroxybenzaldehyde-butanediamine phenol with R being butanediamine groups, and is called BOEF for short.

Fig. 26 shows a BOEF infrared spectrum. Wherein: 1459cm ^-1 The stretching vibration peak of C-C on benzene ring. 1257cm ^-1 The position is a telescopic vibration peak of a C-O-C bond on an oxazine ring; 1097cm ^-1 The C-O characteristic peak of the acetal is the C-O bond characteristic absorption peak of tertiary carbon connected with two O atoms on the acetal ring; 970cm ^-1 The absorption vibration peak of the oxazine ring is positioned; 1145cm ^-1 The vibration peak of the C-N-C bond on the oxazine ring is also shown, and the oxazine ring exists. At 754cm only ^-1 The characteristic peak of benzene ring appears, which indicates phenol end capping, and preliminary indicates that BOEF is successfully synthesized.

Example 19

Benzoxazines were prepared in a similar manner as example 1, except that: 3.30g (0.01 mol) of erythritol parahydroxybenzaldehyde, 1.83ml (0.02 mol) of aniline and 50mL of LDMF were put into a 100ml three-necked flask, 1.381g (0.046 mol) of paraformaldehyde was further added into the three-necked flask in 3 portions, and then the three-necked flask containing the reactant was placed in a constant temperature reaction bath at 95℃for stirring for 30 minutes, and then the temperature was raised to 95℃for reaction for 10 hours. The prepared benzoxazine is erythritol bis-parahydroxybenzaldehyde-aniline benzoxazine.

Example 20

Benzoxazines were prepared in a similar manner as example 19, except that: 3.30g (0.01 mol) of erythritol parahydroxybenzaldehyde, 2.30mL (0.02 mol) of cyclohexylamine and 50mL of DMF are added, and 1.261g (0.042 mol) of paraformaldehyde are added in 3 portions in a three-necked flask. The prepared benzoxazine is erythritol bis-parahydroxybenzaldehyde-cyclohexylamine benzoxazine.

Example 21

Benzoxazines were prepared in a similar manner as example 19, except that: 3.30g (0.01 mol) of erythritol bis-parahydroxybenzaldehyde, 1.977ml (0.02 mol) of n-butylamine and 50ml of LDMF were added, and 1.261g (0.042 mol) of paraformaldehyde was added 3 times to the three-necked flask to prepare benzoxazine, which was erythritol bis-parahydroxybenzaldehyde-n-butylamine type benzoxazine.

Comparative example

Comparative example 1

Bisphenol a-aniline benzoxazine was prepared in a similar manner to example 1, except that: the reactants added were 2.28g (0.01 mol) bisphenol A,1.83mL (0.02 mol) aniline, 50mL toluene, 1.261g (0.042 mol) paraformaldehyde was added 2 to 4 times, and the flask was placed in a low temperature (10 ℃ C.) constant temperature reaction bath and stirred for 30min, then heated to 95 ℃ C., and the stirring was continued for 10h. The molecular structure of the resulting product is shown below:

wherein the yield of the reaction was 75.2%.

FIG. 27 is a DSC curve of bisphenol A-aniline benzoxazine. As can be seen from the figure, the first downward peak is a melting endothermic peak, and the melting peak top temperature is about 110 ℃. The second upward peak is the exothermic peak of oxazine, the initial curing temperature of bisphenol A-aniline benzoxazine is 237 ℃, and the peak top temperature is about 256 ℃.

Experimental example

Experimental example 1

The BPMA prepared in example 9 was cured by stepwise heating at 140 ℃,160 ℃,180 ℃,200 ℃ for 2 hours for each stepwise temperature zone, and finally cooling to room temperature to obtain a BPMA resin (shown in table as example 9).

The bisphenol a-aniline type benzoxazine prepared in comparative example 1 was subjected to step-wise heating according to a program of 140 ℃,160 ℃,180 ℃,200 ℃ and each step temperature section was maintained for 1 hour, and finally ring-opening curing was performed under the condition of cooling to room temperature to obtain bisphenol a-aniline type benzoxazine resin (represented by comparative example 1 in the table).

The BPMA resin and the bisphenol A-aniline benzoxazine resin are respectively degraded under the following conditions, and after degradation is finished, the degradation degree of each group of resin is calculated according to a formula 1 after filtration and drying:

wherein: w (W) ₁ Is the mass of the starting resin;

W ₂ the residue mass.

The degradation conditions and degradation degree results of each group of resins are shown in table 1:

TABLE 1 summary of resin degradation conditions and degradation degrees

Benzoxazine resin species	Solution type (volume ratio)	Temperature/. Degree.C	Reaction time/h	Degradation degree/%
					Comparative example 1	Ethanol-water-acetic acid (0.1M) =4:1:1	85	8	0
Example 9	Ethanol-water-acetic acid (0.1M) =4:1:1	85	8	9
					Example 9	Ethanol-water-acetic acid (0.1M) =4:1:1	85	24	13
Example 9	Ethanol-water-acetic acid (0.1M) =4:1:1	85	48	30
					Example 9	Ethanol-water-hydrochloric acid (0.1M) =4:1:1	85	8	30
Example 9	Ethanol-water-hydrochloric acid (0.1M) =4:1:1	85	24	85
					Example 9	DMF: water: hydrochloric acid (0.1M) =4:1:1	85	8	40
Example 9	DMF: water: hydrochloric acid (0.1M) =4:1:1	85	24	90
					Example 9	DMF: water: hydrochloric acid (1M) =4:1:1	85	8	50
Example 9	DMF: water: hydrochloric acid (1M) =4:1:1	85	24	90.5
					Example 9	Ethanol-water-sulfuric acid (0.1M) =4:1:1	85	8	34.3
Example 9	Ethanol-water-sulfuric acid (0.1M) =4:1:1	85	24	95
					Example 9	DMF: water sulfuric acid (0.1M) =4:1:1	85	8	52.7
Example 9	DMF: water sulfuric acid (0.1M) =4:1:1	85	24	95
					Example 9	DMF: water sulfuric acid (0.1M) =4:1:1	85	48	99

The invention has been described in detail with reference to preferred embodiments and illustrative examples. It should be noted, however, that these embodiments are merely illustrative of the present invention and do not limit the scope of the present invention in any way. Various improvements, equivalent substitutions or modifications can be made to the technical content of the present invention and its embodiments without departing from the spirit and scope of the present invention, which all fall within the scope of the present invention. The scope of the invention is defined by the appended claims.

Claims

1. A benzoxazine comprising an erythritol acetal structure, said benzoxazine comprising the unit (I) shown below:

2. The benzoxazine according to claim 1, which contains a free hydroxyl group, comprising any one or several of the units (vii) to (x) as shown below:

3. The benzoxazine of claim 1, which is a benzoxazine capped with aniline or phenol.

4. A process for the preparation of a benzoxazine containing an erythritol acetal structure according to any of claims 1-3, said process comprising: and carrying out temperature-rising reflux reaction on phenols, amines and aldehydes in an organic solvent to obtain the benzoxazine.

5. The method of claim 4, wherein the phenol is a bisphenol comprising an erythritol acetal structure; the amine comprises aliphatic amine, aromatic amine and alicyclic amine; the aldehyde is paraformaldehyde or formaldehyde aqueous solution; the organic solvent is selected from any one or more of dioxane, methanol, ethanol, dioxane, N-methylpyrrolidone, chloroform, toluene and N, N-dimethylformamide.

6. The method of claim 4 or 5, wherein the molar ratio of phenolic hydroxyl groups in the phenols, amine groups in the amines, aldehyde functional groups in the aldehydes is 1: (0.1-5): (0.5-8).

7. The method according to claim 4, wherein phenols, amines and aldehydes are directly mixed with an organic solvent and subjected to a temperature-rising reflux reaction.

8. The method according to claim 4, wherein phenols and amines are dissolved in an organic solvent, and aldehydes are added in 3 to 5 batches, and a temperature-rising reflux reaction is performed.

9. A method of preparing a resin from the benzoxazine containing erythritol acetal structure according to any of claims 1-3, the method comprising: the benzoxazine containing erythritol acetal structure is cured.

10. The method of claim 9, wherein the curing temperature is 80-280 ℃ and the curing time is 6-16 h.