CN115433333A

CN115433333A - Benzoxazine resin with erythritol acetal structure

Info

Publication number: CN115433333A
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: 2022-12-06
Anticipated expiration: 2041-06-02
Also published as: CN115433333B

Abstract

The invention discloses novel chemically degradable benzoxazine resin, wherein benzoxazine containing an erythritol acetal structure is prepared by condensation reaction of a phenol source containing the erythritol acetal structure, amines and aldehydes, and is cured to obtain resin or cured substance, or a composite material prepared from the benzoxazine containing the erythritol acetal structure can be completely degraded under an acidic condition, after separation and recovery of degradation products, the material recycling can be realized, the problem that a cross-linked network structure after the benzoxazine is cured is insoluble and cannot be degraded is solved, and the prepared benzoxazine containing the erythritol acetal structure has excellent rigidity.

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 containing a nitrogen-oxygen six-membered heterocyclic ring structure and is obtained by Mannich condensation reaction of an amine compound, a phenolic compound and formaldehyde. When a curing agent is added or heated, benzoxazine undergoes ring-opening curing to form a nitrogen-containing crosslinked network structure, so that the benzoxazine is also called ring-opening phenolic resin.

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

Meanwhile, the benzoxazine has some defects, such as high curing temperature which generally reaches 200 ℃, and long curing time; the benzoxazine resin obtained after the traditional benzoxazine polymerization is brittle and has not very high mechanical property; the processing process is complicated, most benzoxazine monomers are solid, and the benzoxazine monomers are difficult to use conveniently like liquid thermosetting resin prepolymers in the processing process; the prepolymer has a low molecular weight and is difficult to process into a film.

In order to overcome the defects, scientific research workers develop the benzoxazine with a novel structure by utilizing the flexible molecular design of the benzoxazine, namely, a synthetic monomer or a copolymer thereof contains benzoxazine rings, the benzoxazine monomer can be dissolved in a solvent and can also be processed in a molten state, and the material after heating and curing is still a thermosetting polymer. The benzoxazine resin has the advantages of both thermosetting resin and thermoplastic resin, has good application prospect, and can be used as electronic packaging, printed circuit board, aviation and film materials.

The crosslinked network structure of the benzoxazine resin after curing is insoluble, and the application of the benzoxazine resin is greatly limited in the aspects of recycling and degradability. How to degrade and recycle the cured benzoxazine is a real problem. Under the guidance of national policies, the industrial recycling and reusing process of the thermosetting carbon fiber composite waste with low energy consumption and good recycling effect is to be developed vigorously, so that the resource recycling and reusing of the composite waste are realized, and the method has important significance for building a resource-saving and environment-friendly harmonious society and responding to calls for environment protection, energy conservation, emission reduction and sustainable development at home and abroad.

Disclosure of Invention

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

Specifically, the present invention aims to provide the following:

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

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

In a second aspect, there is provided a method for preparing a benzoxazine of an erythritol acetal structure, the method comprising: and heating phenol, amine and aldehyde in an organic solution for reflux reaction to obtain the benzoxazine.

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

The invention has the advantages 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, a cured substance or a composite material prepared from the benzoxazine can be completely degraded under an acidic condition, the recycling of the material is realized, and the problem that the benzoxazine cannot be degraded due to insolubility of a cross-linked network structure after being cured 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 is simple in preparation method and is green and environment-friendly. The prepared benzoxazine has high mechanical property and meets the industrial requirement.

Drawings

FIG. 1 shows the infrared spectrum of example 1;

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

FIG. 3 shows a DSC plot for example 1;

FIG. 4 shows an infrared spectrum of example 2;

FIG. 5 shows a DSC plot for example 2;

FIG. 6 shows the infrared spectrum of example 3;

FIG. 7 shows the DSC plot of example 3;

FIG. 8 shows the infrared spectrum of example 4;

FIG. 9 shows the infrared spectrum of example 5;

FIG. 10 shows an infrared spectrum of example 6;

FIG. 11 shows the infrared spectrum of example 7;

FIG. 12 shows a chart of the infrared spectrum of example 8;

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

FIG. 14 shows DSC plots of example 8;

FIG. 15 shows an infrared spectrum of example 9;

FIG. 16 shows DSC plots of example 9;

FIG. 17 shows the DSC plot of example 10;

FIG. 18 is a chart showing an infrared spectrum of example 11;

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

FIG. 20 shows DSC plots of example 11;

FIG. 21 is a chart showing the infrared spectrum of example 12;

FIG. 22 shows the DSC plot of example 12;

FIG. 23 shows DSC plots of example 13;

FIG. 24 is a chart showing the infrared spectrum of example 14;

FIG. 25 is a chart showing the infrared spectrum of example 16;

FIG. 26 is a chart showing the infrared spectrum of example 18;

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

Detailed Description

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

In a preferred embodiment, the benzoxazine contains free hydroxyl groups and includes any one or more of units (II) to (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 aniline group comprising the unit (vi) shown below:

wherein R is aliphatic group, alicyclic group, aromatic group, or the derivatives of aliphatic group, alicyclic group, aromatic group, n is not less than 1 and not more than 30, n is integer.

In a preferred embodiment, the benzoxazine is one terminated with an aniline group, and includes any one or more of the following units (vii) to (x):

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

in a preferred embodiment, the benzoxazine is erythritol bis-p-hydroxybenzaldehyde-cyclohexylamine type benzoxazine having the following structural formula:

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

in a second aspect of the present invention, there is provided a method for preparing a benzoxazine with an erythritol acetal structure, the method being a solution method, specifically comprising: and heating phenol, amine and aldehyde in an organic solution for reflux reaction to obtain the benzoxazine.

Compared with other methods such as suspension method, the solution method has the advantages of low system viscosity, uniform mixing, easy temperature control and the like, and has higher yield. It has been shown that the reaction in different solvents has an effect on the yield of benzoxazine monomers, for example, dimers or polymers decrease the content of benzoxazine monomers and affect the purity.

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

According to the invention, the phenols are bisphenols containing an erythritol acetal structure, such as: erythritol bis-p-hydroxybenzaldehyde (p-sq, chemical formula shown in formula 1), erythritol bis-m-hydroxybenzaldehyde (m-sq, chemical formula shown in formula 2), erythritol bis-o-hydroxybenzaldehyde (o-sq, chemical formula shown in formula 3), erythritol bis-vanillin (v-sq, chemical formula shown in formula 4), and erythritol bis-isovanillin (i-sq, chemical formula shown in formula 5).

The inventor finds that the resin or the compound prepared from the benzoxazine containing the erythritol acetal structure can be degraded under the acidic condition, the material recycling can be realized through separation, the environment is very friendly, and particularly, the benzoxazine prepared by providing the erythritol acetal structure required by the benzoxazine by utilizing the bisphenol containing the erythritol acetal structure has excellent heat resistance and rigidity.

According to the present invention, the amines include aliphatic amines such as butanediamine, 1, 5-pentanediamine, n-butane, cyclohexane, aromatic amines such as 4-aminobiphenyl, 4' -diaminodiphenylmethane, 2, 4-diaminotoluene, aniline, alicyclic amines such as isophoronediamine, 4-diaminodicyclohexylmethane, 1, 3-cyclohexyldimethylamine, preferably selected from any one or a 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 bifunctional compounds, can form a compound with high polymerization degree and a long molecular chain structure, and has thermosetting property. According to the traditional method, bisphenol monoamines or monophenol diamine is used as a raw material, the prepared benzoxazine resin is low in molecular weight, and a cross-linked network molecular chain formed during high-temperature curing is short and small in molecular free volume, so that the prepared cured material is poor in flexibility and dielectric property.

In the invention, the benzoxazine prepared by using the bisphenol containing the erythritol acetal structure as the raw material not only has excellent thermosetting property, but also can be completely degraded.

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

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

Wherein the molar ratio of phenols to phenol is 1: (1.5 to 3), for example, 1.

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

In this case, 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, the phenol and the amine are dissolved in the organic solvent, and the aldehyde is added in portions, for example, 3 to 5 times, and subjected to a heating reflux reaction.

In this case, 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 order of addition of the reactants is different, and there are differences in optimum reaction temperature and reaction time for preparing benzoxazine containing an erythritol acetal structure. In the reaction process, the structure of a reaction product can be influenced by the reaction temperature and the reaction time, side reactions can be caused by overhigh or overlow reaction temperature and overlong or overlow reaction time, and the reaction system is homogeneous in the reaction temperature and reaction time range, so that the high-quality benzoxazine can be obtained.

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

Among them, the washing includes alkali washing and water washing, and the alkali washing preferably uses an aqueous strong alkali solution, such as an aqueous sodium hydroxide solution.

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

Wherein the curing temperature is 80-280 ℃, preferably 100-240 ℃, and 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 step temperature rise, one temperature step for every 15 to 20 ℃, and each temperature step reacts for 1 to 2 hours.

The inventors have found that if isothermal curing is used, the curing reaction can be carried out at a lower temperature, but the curing time is longer, while the reaction time is shorter at a higher temperature. When the curing reaction is carried out at a lower temperature, the curing reaction is mild, a compact network cured product can be obtained, but reactive groups are frozen at the later stage of the curing reaction, the curing reaction is incomplete, and the glass transition temperature after curing is lower. If the curing is carried out at a higher temperature, the reaction speed is severe, so that a larger internal stress is generated, more defects are generated, and the mechanical property is poor. When a 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 condensate prepared from the benzoxazine containing the erythritol acetal structure can be completely dissolved in an acid solution, and has great application potential in the aspects of recovery and degradability.

When degrading, the resin or the condensate 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 of organic acids such as formic acid, acetic acid, trifluoromethanesulfonic acid, trichloroacetic acid, or inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid.

According to the present invention, the acidic solution is a mixture of an organic acid or an inorganic acid with a polar solvent including 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 present invention is further described below by way of specific examples, which are merely exemplary and do not limit the scope of the present invention in any way.

Example 1

A50 ml three-necked flask was charged with 1.65g (0.005 mol) of erythritol parahydroxybenzaldehyde bis (p-hydroxybenzaldehyde), 0.44g (0.005 mol) of butanediamine, 0.60g (0.02 mol) of paraformaldehyde and 20mL of N, N-Dimethylformamide (DMF), and the reaction was carried out at 115 ℃ for 24 hours while setting the reflux reaction temperature. 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 the reaction product to be neutral by using deionized water, filtering, and drying at 50 ℃ to obtain a final product erythritol bis-p-hydroxybenzaldehyde-butanediamine benzoxazine containing free hydroxyl and containing a unit II, wherein R is butanediamine, and BPED is short.

FIG. 1 shows a BPED infrared spectrum. Wherein: 1501cm ^-1 Is located at 1389cm which is a C-C stretching vibration peak on a benzene ring ^-1 In the form of-CH in butanediamine ₂ -absorption vibration peak of. 1219cm ^-1 The position is a stretching vibration peak of a C-O-C bond on the oxazine ring; 1054cm ^-1 The absorption peak is the C-O characteristic peak of acetal, namely the C-O bond characteristic absorption peak of tertiary carbon connected with two O atoms on an acetal ring; 974cm ^-1 The peak is the absorption vibration peak of the oxazine ring; 1083cm ^-1 Is a stretching vibration peak of a C-O-C bond on an acetal ring; 1154cm ^-1 The peak is also the vibration peak of the C-N-C bond on the oxazine ring, and it can be seen that an oxazine ring is present. At 3386cm ^-1 Can observe a stretching vibration peak of-OH, and the two ends of the surface oxazine are free hydroxyl of acetal bisphenolPreliminary demonstration of successful synthesis of BPED.

Fig. 2 shows a BPED nuclear magnetic hydrogen spectrum. Wherein: a newly appeared proton peak Ha at the chemical shift delta =5.39ppm, belonging to hydrogen on the middle carbon of the oxazine ring N-C-C structure; the chemical shift delta =4.85ppm belongs to a proton peak Hb, the chemical shifts of four positions d, e, f and g on the middle spiral ring structure are changed from 4.27ppm-3.87ppm to 4.26ppm-3.45ppm, and the chemical shifts of two kinds of hydrogen are overlapped. Integration of the peak areas was performed, consistent with the theoretical above-mentioned ratios of hydrogen in the positions, to determine successful incorporation of BPED (CDCl at δ =7.29 ppm) ₃ Solvent peak of (1).

FIG. 3 shows a DSC curve of BPED, which is known to have a curing peak temperature of 191 ℃.

Example 2

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

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

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

Example 3

A benzoxazine was prepared in a similar manner to example 1, except that: the reactants added were 3.30g (0.01 mol) of erythritol bis-p-hydroxybenzaldehyde, 2.10g (0.01 mol) of 4,4' -diaminodicyclohexylmethane, 1.2g (0.04 mol) of paraformaldehyde and 50ml of DMF. The prepared benzoxazine is erythritol bis p-hydroxybenzaldehyde-4, 4 '-diaminodicyclohexyl methane main chain type benzoxazine containing free hydroxyl and containing a unit II, wherein R is 4,4' -diaminodicyclohexyl methyl alkyl, and is called BPHD for short.

Wherein the yield of the reaction obtained was 90.6%.

Fig. 6 shows a BPHD infrared spectrum. Wherein: 1502cm ^-1 Is at the stretching vibration peak of C-C on the benzene ring, 1379cm ^-1 Is treated as-CH in PACM ₂ -absorption vibration peak of (a). 1234cm ^-1 The position is a stretching vibration peak of a C-O-C bond on the oxazine ring; 974cm ^-1 The peak is the absorption vibration peak of the oxazine ring; 1096cm ^-1 Is a stretching vibration peak of a C-O-C bond on an acetal ring; 1152cm ^-1 The peak is also the vibration peak of the C-N-C bond on the oxazine ring, and it can be seen that an oxazine ring is present. At 3416cm ^-1 A stretching vibration peak of-OH can be observed, and the two ends of the surface oxazine are free hydroxyl of acetal bisphenol, which preliminarily shows that the BPHD is successfully synthesized.

Fig. 7 shows a DSC curve of BPHD, and it is found that the curing peak temperature of BPHD is 228 ℃.

Example 4

A benzoxazine was prepared in a similar manner to 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 20ml DMF. The prepared benzoxazine is erythritol double-condensed m-hydroxybenzaldehyde-butanediamine main chain type benzoxazine containing free hydroxyl and containing a unit III, wherein R is butanediamine, and BMED is short.

FIG. 8 shows a BMED infrared spectrum. Wherein: 1243cm ^-1 Is arranged asA stretching vibration peak of a C-O-C bond on the oxazine ring; 973cm ^-1 The peak is the absorption vibration peak of the oxazine ring; 1172cm ^-1 The position is also the vibration peak of the C-N-C bond on the oxazine ring, and it can be seen that an oxazine ring is present. At 3403cm ^-1 A stretching vibration peak of-OH can be observed, and the two ends of the surface oxazine are free hydroxyl of acetal bisphenol, which preliminarily shows that the BMED is successfully synthesized.

Example 5

A benzoxazine was prepared in a similar manner to 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 20ml DMMF. The prepared benzoxazine is erythritol bis-m-hydroxybenzaldehyde-4, 4 '-diaminodiphenylmethane main chain type benzoxazine containing free hydroxyl and containing a unit III, wherein R is 4,4' -diaminodiphenylmethane, and is abbreviated as BMMD.

Fig. 9 shows a BMMD ir spectrum. Wherein: 1231cm ^-1 The position is a stretching vibration peak of a C-O-C bond on the oxazine ring; 974cm ^-1 The peak is the absorption vibration peak of the oxazine ring; 1167cm ^-1 The peak is also the vibration peak of the C-N-C bond on the oxazine ring, and it can be seen that an oxazine ring is present. At 3380cm ^-1 A stretching vibration peak of-OH can be observed, and the two ends of the surface oxazine are free hydroxyl of acetal bisphenol, which initially indicates that the BMMD is successfully synthesized.

Example 6

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

FIG. 10 shows a BIED infrared spectrum. Wherein: 1219cm ^-1 The position is a stretching vibration peak of a C-O-C bond on the oxazine ring; 968cm ^-1 The peak is the absorption vibration peak of the oxazine ring; 1163cm ^-1 Where is also C-N on the oxazine ringThe peak of the C bond oscillation, and the presence of an oxazine ring can be seen. At 3416cm ^-1 A stretching vibration peak of-OH can be observed, and the two ends of the surface oxazine are free hydroxyl of acetal bisphenol, which preliminarily shows that BIED is successfully synthesized.

Example 7

A benzoxazine was prepared in a similar manner to example 1, except that: the reactants added were 1.95g (0.005 mol) erythritol isovanillin, 0.99g (0.005 mol) 4,4' -diaminodiphenylmethane, 0.60g (0.02 mol) paraformaldehyde and 20ml DMF. The prepared benzoxazine is erythritol double-condensed isovanillin-4, 4 '-diaminodiphenylmethane main chain type benzoxazine containing free hydroxyl and containing a unit V, wherein R is 4,4' -diaminodiphenylmethane, and the short is as follows: BIMD.

Fig. 11 shows BIMD infrared spectra. Wherein: 1249cm ^-1 The position is a stretching vibration peak of a C-O-C bond on the oxazine ring; 970cm ^-1 The peak is the absorption vibration peak of the oxazine ring; 1165cm ^-1 The position is also the vibration peak of the C-N-C bond on the oxazine ring, and it can be seen that an oxazine ring is present. At 3420cm ^-1 A stretching vibration peak of-OH can be observed, and the two ends of the surface oxazine are free hydroxyl of acetal bisphenol, which preliminarily shows that BIMD is successfully synthesized.

Example 8

A benzoxazine was prepared in a similar manner to example 1, except that: the reactants added were 6.60g (0.02 mol) erythritol bis-p-hydroxybenzaldehyde, 0.88g (0.01 mol) butanediamine, 1.86g (0.02 mol) aniline, 2.40g (0.08 mol) paraformaldehyde and 50ml DMF. The prepared benzoxazine is terminated by aniline group, and contains erythritol bis-p-hydroxybenzaldehyde-butanediamine aniline terminated main chain type benzoxazine with a unit VI and a unit R of butanediamine group, and is called BPEA for short.

FIG. 12 shows a BPEA infrared spectrum. Wherein: 1281cm ^-1 The position is a stretching vibration peak of a C-O-C bond on the oxazine ring; 979cm ^-1 The peak is the absorption vibration peak of the oxazine ring; 1158cm ^-1 The peak is also the vibration peak of the C-N-C bond on the oxazine ring, and it can be seen that an oxazine ring is present. 760 and 695cm ^-1 Characteristic peak of monosubstituted benzene ringIndicating aniline capping and preliminary successful synthesis of BPEA.

Fig. 13 shows a BPEA nuclear magnetic hydrogen spectrum. 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 middle carbon of the N-structure. With reference to FIG. 9, it can be shown that BPEA was successfully synthesized

FIG. 14 shows a BPEA DSC curve, from which it can be seen that the first downward peak is the melting endotherm and the melting peak top temperature is around 80 ℃. The second upward peak is the curing exotherm peak of oxazines, the initial curing temperature of BPEA is 145 ℃, and the peak top temperature is around 230 ℃.

Example 9

A benzoxazine was prepared in a similar manner to example 1, except that: the reactants added were 6.60g (0.02 mol) of erythritol bis-p-hydroxybenzaldehyde, 1.98g (0.01 mol) of 4,4' -diaminodiphenylmethane, 1.86g (0.02 mol) of aniline, 2.40g (0.08 mol) of paraformaldehyde and 50ml of DMF. The prepared benzoxazine is end-capped by aniline group, and contains erythritol bis-p-hydroxybenzaldehyde-4, 4 '-diaminodiphenylmethane aniline with a unit VI and R being 4,4' -diaminodiphenylmethane alkyl, and is called BPMA for short.

Fig. 15 shows a BPMA infrared spectrum. Wherein: 1281cm ^-1 The position is a stretching vibration peak of a C-O-C bond on the oxazine ring; 979cm ^-1 The peak is the absorption vibration peak of the oxazine ring; 1158cm ^-1 The peak is also the vibration peak of the C-N-C bond on the oxazine ring, and it can be seen that an oxazine ring is present. 760 and 695cm ^-1 The characteristic peak of the mono-substituted benzene ring indicates that aniline is blocked, and the synthesis of BPMA is primarily indicated.

Fig. 16 shows a DSC curve for BPMA, from which a melting peak temperature of 114 ℃ and a solidification peak temperature of 192 ℃ are read.

Example 10

A benzoxazine was prepared in a similar manner to example 1, except that: the reactants added were 6.60g (0.02 mol) of erythritol bis-p-hydroxybenzal, 2.10g (0.01 mol) of 4,4' -diaminodicyclohexylmethane, 1.86g (0.02 mol) of aniline, 2.40g (0.08 mol) of paraformaldehyde and 50ml of DMF. The prepared benzoxazine is end-capped by aniline group, and contains erythritol bis p-hydroxybenzaldehyde-4, 4 '-diaminodicyclohexyl methane aniline with a unit VI and R being 4,4' -diaminodicyclohexyl methane alkyl, and is called BPHA 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

A benzoxazine was prepared in a similar manner to example 1, except that: the reactants added were 3.30g (0.01 mol) erythritol bis-p-hydroxybenzaldehyde, 0.88g (0.01 mol) butanediamine, 0.94g (0.01 mol) phenol, 1.20g (0.04 mol) paraformaldehyde and 20ml DMMF. The prepared benzoxazine is end-capped by a phenol group, contains a unit VII, and is erythritol bis-p-hydroxybenzaldehyde-butanediamine phenol end-capped main chain type benzoxazine with R being butanediamine group, which is called BPEF for short.

FIG. 18 shows a BPEF infrared spectrum. Wherein: 1493cm ^-1 Is located at 1387cm which is a stretching vibration peak of C-C on a benzene ring ^-1 In the form of-CH in butanediamine ₂ -absorption vibration peak of. 1259cm ^-1 The position is a stretching vibration peak of a C-O-C bond on the oxazine ring; 1096cm ^-1 The characteristic peak of C-O of acetal is the characteristic absorption peak of C-O bond of tertiary carbon connected with two O atoms on the acetal ring; 974cm ^-1 The peak is the absorption vibration peak of the oxazine ring; 1152cm ^-1 The peak is also the vibration peak of the C-N-C bond on the oxazine ring, and it can be seen that an oxazine ring is present. Only at 757cm ^-1 The characteristic peak of the benzene ring appears, which indicates that the phenol is blocked and initially indicates that the BPEF is successfully synthesized.

Fig. 19 shows a BPEF nuclear magnetic hydrogen spectrum. 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 middle carbon of the N-structure. The successful synthesis of BPEF is illustrated in connection with FIG. 13.

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

Example 12

A benzoxazine was prepared in a similar manner to example 1, except that: the reactants added were 3.30g (0.01 mol) of erythritol bis-p-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 20ml of DMF. The prepared benzoxazine is end-capped by a phenol group, and contains erythritol bis-p-hydroxybenzaldehyde-4, 4 '-diaminodiphenylmethane phenol end-capped main chain type benzoxazine with a unit VII and R being 4,4' -diaminodiphenylmethane alkyl, which is called BPMF for short.

Fig. 21 shows a BPMF infrared spectrum. Wherein: 1513cm ^-1 The position is a stretching vibration peak of C-C on a benzene ring. 1228cm ^-1 The position is a stretching vibration peak of a C-O-C bond on the oxazine ring; 1095cm ^-1 The characteristic peak of C-O of acetal is the characteristic absorption peak of C-O bond of tertiary carbon connected with two O atoms on the acetal ring; 972cm ^-1 The peak is the absorption vibration peak of the oxazine ring; 1152cm ^-1 The position is also the vibration peak of the C-N-C bond on the oxazine ring, and it can be seen that an oxazine ring is present. At 756cm only ^-1 The characteristic peak of the benzene ring appears, which indicates that the phenol is blocked, and the preliminary result can indicate that the BPMF is successfully synthesized.

Fig. 22 shows a DSC curve of BPMF, from which it is read that the melting peak temperature of BPMF is 117 ℃ and the solidification peak temperature is 223 ℃.

Example 13

A benzoxazine was prepared in a similar manner to example 1, except that: the reactants added were 3.30g (0.01 mol) of erythritol bis-p-hydroxybenzaldehyde, 4.20g (0.02 mol) of 4,4' -diaminodicyclohexylmethane, 1.88g (0.02 mol) of phenol, 2.40g (0.08 mol) of paraformaldehyde and 50ml of DMF. The prepared benzoxazine is end-capped by a phenol group, and contains erythritol bis-p-hydroxybenzaldehyde-4, 4 '-diaminodicyclohexyl methane phenol end-capped main chain type benzoxazine with a unit VII and R being 4,4' -diaminodicyclohexyl methane-base, which is BPHF for short.

FIG. 23 shows a BPHF DSC curve, which indicates that the curing peak temperature of BPHF is 224 ℃.

Example 14

A benzoxazine was prepared in a similar manner to 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 20ml of DMF. The prepared benzoxazine is end-capped by a phenol group, and contains erythritol bis-m-hydroxybenzaldehyde-4, 4 '-diaminodiphenylmethane phenol end-capped main chain type benzoxazine with a unit VIII and R of 4,4' -diaminodiphenylmethane alkyl, which is called BMMF for short.

Fig. 24 shows a BMMF infrared spectrum. Wherein: 1513cm ^-1 The position is a stretching vibration peak of C-C on a benzene ring. 1228cm ^-1 The position is a stretching vibration peak of a C-O-C bond on the oxazine ring; 1092cm ^-1 The absorption peak is the C-O characteristic peak of acetal, namely the C-O bond characteristic absorption peak of tertiary carbon connected with two O atoms on an acetal ring; 970cm ^-1 The peak is the absorption vibration peak of the oxazine ring; 1177cm ^-1 The peak is also the vibration peak of the C-N-C bond on the oxazine ring, and it can be seen that an oxazine ring is present. At 748cm only ^-1 The characteristic peak of the benzene ring appears, which indicates that the phenol is blocked and initially indicates that the BMMF is successfully synthesized.

Example 15

A benzoxazine was prepared in a similar manner to example 1, except that: the reactants added were 3.30g (0.01 mol) of erythritol bis-ortho-hydroxybenzaldehyde, 3.97g (0.02 mol) of 4,4' -diaminodiphenylmethane, 1.88g (0.02 mol) of phenol, 2.40g (0.08 mol) of paraformaldehyde and 50ml of DMF. The prepared benzoxazine is end-capped by a phenol group, and contains erythritol double-condensed o-hydroxybenzaldehyde-4, 4 '-diaminodiphenylmethane phenol end-capped main chain type benzoxazine of which the unit IX and R are 4,4' -diaminodiphenylmethane, which is called BOMF for short.

Example 16

A benzoxazine was prepared in a similar manner to example 1, except that: the reactants added were 3.90g (0.01 mol) erythritol bis-vanillin, 3.97g (0.02 mol) 4,4' -diaminodiphenylmethane, 1.88g (0.02 mol) phenol, 2.40g (0.08 mol) paraformaldehyde and 50ml DMF. The prepared benzoxazine is end-capped by a phenol group, and erythritol double-condensed vanillin-4, 4 '-diaminodiphenylmethane phenol end-capped main chain type benzoxazine containing the unit X and the unit R which are 4,4' -diaminodiphenylmethane alkyl is called BVMF for short.

Fig. 25 shows BVMF infrared spectrum. Wherein: 1513cm ^-1 The position is a stretching vibration peak of C-C on a benzene ring. 1228cm ^-1 The position is a stretching vibration peak of a C-O-C bond on the oxazine ring; 1101cm ^-1 The absorption peak is the C-O characteristic peak of acetal, namely the C-O bond characteristic absorption peak of tertiary carbon connected with two O atoms on an acetal ring; 974cm ^-1 The peak is the absorption vibration peak of the oxazine ring; 1151cm ^-1 The peak is also the vibration peak of the C-N-C bond on the oxazine ring, and the existence of the oxazine ring can be seen. Only at 757cm ^-1 The characteristic peak of a benzene ring appears, which indicates that the end capping of phenol is performed, and initially indicates that the BVMF is successfully synthesized.

Example 17

A benzoxazine was prepared in a similar manner to example 1, except that: 1.65g (0.005 mol) of erythritol bis-condensed o-hydroxybenzaldehyde, 0.44g (0.005 mol) of butanediamine, 0.60g (0.02 mol) of paraformaldehyde and 20ml of DMF were added. The prepared benzoxazine is erythritol double-condensed ortho-hydroxybenzaldehyde-butanediamine main chain type benzoxazine containing free hydroxyl and containing a unit IV, wherein R is butanediamine, and BOED is short.

Example 18

A benzoxazine was prepared in a similar manner to example 1, except that: the reactants added were 3.30g (0.01 mol) of erythritol bis-ortho-hydroxybenzaldehyde, 0.88g (0.01 mol) of butanediamine, 0.94g (0.01 mol) of phenol, 1.20g (0.04 mol) of paraformaldehyde and 20ml of DMMF. The prepared benzoxazine is end-capped by a phenol group, and contains an erythritol double-condensed o-hydroxybenzaldehyde-butanediamine phenol end-capped main chain type benzoxazine with a unit IX and R as butanediamine, which is called BOEF for short.

FIG. 26 shows a BOEF infrared spectrum. Wherein: 1459cm ^-1 The position is a stretching vibration peak of C-C on a benzene ring. 1257cm ^-1 The position is a stretching vibration peak of a C-O-C bond on the oxazine ring; 1097cm ^-1 Is a C-O characteristic peak of acetal, namely C-O of tertiary carbon connected with two O atoms on an acetal ringA characteristic bond absorption peak; 970cm ^-1 The peak is the absorption vibration peak of the oxazine ring; 1145cm ^-1 The position is also the vibration peak of the C-N-C bond on the oxazine ring, and it can be seen that an oxazine ring is present. Only at 754cm ^-1 The occurrence of characteristic peaks of benzene rings indicates the end capping of phenol, which initially indicates the successful synthesis of BOEF.

Example 19

A benzoxazine was prepared in a similar manner to example 1, except that: 3.30g (0.01 mol) of erythritol bis-p-hydroxybenzaldehyde, 1.83ml (0.02 mol) of aniline and 50ml of DMF were added to a 100ml three-necked flask, 1.381g (0.046 mol) of paraformaldehyde was further added thereto in 3 portions in the three-necked flask, and then the three-necked flask containing the reactants was placed in a constant temperature reaction bath at a temperature of 95 ℃ and stirred for 30min, and then heated to 95 ℃ to react for 10 hours. The prepared benzoxazine is erythritol bis-p-hydroxybenzaldehyde-aniline type benzoxazine.

Example 20

A benzoxazine was prepared in a similar manner to example 19, except that: 3.30g (0.01 mol) of erythritol p-hydroxybenzene bis-acetal, 2.30mL (0.02 mol) of cyclohexylamine and 50mL of DMF were added, and 1.261g (0.042 mol) of paraformaldehyde was further added in 3 portions in a three-necked flask. The prepared benzoxazine is erythritol bis-p-hydroxybenzaldehyde-cyclohexylamine type benzoxazine.

Example 21

A benzoxazine was prepared in a similar manner to example 19, except that: 3.30g (0.01 mol) of erythritol p-hydroxybenzaldehyde bis-p-hydroxybenzaldehyde, 1.977ml (0.02 mol) of n-butylamine and 50ml of DMF were added, and 1.261g (0.042 mol) of paraformaldehyde was further added in 3 portions in a three-necked flask to obtain benzoxazine which was erythritol p-hydroxybenzaldehyde-n-butylamine type benzoxazine.

Comparative example

Comparative example 1

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

the yield of the reaction was 75.2% of the total.

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

Examples of the experiments

Experimental example 1

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

And (2) heating the bisphenol A-aniline benzoxazine prepared in the comparative example 1 in steps according to the program of 140 ℃,160 ℃,180 ℃ and 200 ℃, keeping the temperature of each step for 1 hour, and finally cooling to room temperature for ring-opening curing to obtain the bisphenol A-aniline benzoxazine resin (shown as the comparative example 1 in the table).

Respectively degrading the BPMA resin and the bisphenol A-aniline benzoxazine resin under the following conditions, filtering and drying after degradation is finished, and calculating the degradation degree of each group of resins according to formula 1:

in the formula: w is a group of ₁ Is the mass of the starting resin;

W ₂ is the amount of the residue。

The degradation conditions and degradation degree results for each resin set are shown in table 1:

TABLE 1 summary of the resin degradation conditions and degradation degrees

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

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

Claims

1. A benzoxazine of an erythritol acetal structure comprising unit (I) as shown below:

2. The benzoxazine according to claim 1, which contains free hydroxyl groups and comprises any one or more of the following units (II) to (v):

3. The benzoxazine according to claim 1, which is a benzoxazine terminated with an aniline group or a phenol group.

4. A method for preparing a benzoxazine of erythritol acetal structure, the method comprising: and heating phenol, amine and aldehyde in an organic solution for reflux reaction to obtain the benzoxazine.

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

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

7. The method of claim 4, wherein the phenols, amines and aldehydes are directly mixed with the organic solution and subjected to a reflux reaction at elevated temperature.

8. The method of claim 4, wherein the phenols and amines are dissolved in the organic solvent, the aldehydes are added in 3-5 batches, and the reaction is carried out under heating and reflux.

9. A method for preparing a resin from a benzoxazine of an erythritol acetal structure, the method comprising: curing the benzoxazine containing the erythritol acetal structure.

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