CN110551140B - Benzoxazine resin containing spiro acetal structure and preparation method thereof - Google Patents
Benzoxazine resin containing spiro acetal structure and preparation method thereof Download PDFInfo
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Abstract
The invention discloses a benzoxazine resin containing a spiro acetal structure and a preparation method thereof, the benzoxazine resin is prepared from a bisphenol compound containing the spiro acetal structure, a primary amine compound and an aldehyde compound through a solution synthesis method, the preparation method has simple process and mild conditions, large-scale industrial production can be realized, and a cured product of the prepared benzoxazine resin after curing has good chemical degradation property and can be degraded under an acidic condition, so that a composite material product can be recycled, resources are saved, and good environmental benefits are achieved.
Description
Technical Field
The invention relates to benzoxazine resin and a preparation method thereof, in particular to benzoxazine resin containing a spiro acetal structure and a preparation method thereof
Background
Along with the development of society, the requirements of people on materials are more and more strict, and the recycling of composite material wastes has important significance on the sustainable development of resources and environment. In China, with the development of the industries such as aerospace, new energy, rail transit, wind power and the like, the application field of the thermosetting resin-based composite material is continuously expanded, and accordingly, the problem of recycling the thermosetting resin-based composite material waste is more and more prominent. Many research institutions at home and abroad have already proposed related problems and researched the recovery problem [ chemical information, Ningbo materials institute composite material green recovery research advances [ J ] chemical novel materials, 2013 (2): 168-168.].
At present, comprehensive treatment becomes a new direction for recycling composite materials, and the main research direction is roughly divided into two aspects: the method is characterized by comprising the following steps of firstly, researching a new treatment technology of non-renewable thermosetting composite material waste; second, a new renewable and degradable material is developed [ shixijun, shigeling, zuirqing, current recycling situation of composite materials at home and abroad [ J ] plastic industry, 2011, 39 (1): 14-18.].
For the degradation and recovery of thermosetting resin, many experts and scholars at home and abroad have conducted relevant research, and the main methods include a physical method and a chemical method, wherein the physical method mainly adopts mechanical pulverization and recovery, and the chemical method mainly includes a pyrolysis method and a solvent method [ Xuping, mu Li Juan, Li Xiao, Li Qian ] research progress on recovery method of thermosetting resin-based composite material [ J]Engineering plastic application, 2013, 41 (1): 100-104.]. Shanxi coal chemical institute Hou-Xiang forest team using coordination unsaturated zinc ionThe carbon-nitrogen bond of the broken epoxy resin is selected, so that the high-efficiency degradation and cyclic utilization of the carbon fiber reinforced epoxy resin are realized; degradation recovery of glass fiber reinforced unsaturated polyester resins is achieved by selective cleavage of the ester bonds by weakly coordinating aluminum ions [ Deng T S, Liu Y, Cui XJ, et al. Cleavage of C-N bonds in carbon fiber/epoxy resins composites. Green Chemistry, 2015, 17, 2141-.]. Iwaya et al in solvents of diethylene glycol monomethyl ether and phenethyl alcohol, in K3PO4Under the catalysis of (2), the unsaturated polyester is reacted for 1-8 h at 190-350 ℃, and the long GF is obtained through recovery [ Iwaya T, et al. recycling of fiber recycled plastics using polymerization by Solvotherm Sci, 2008, 43 (7): 2452-2456.]。
The disposal of thermosetting composite material waste in China mainly adopts landfill and incineration, and the landfill method occupies land resources and causes soil damage. Incineration does not cause land waste, but secondary pollution is caused due to a large amount of toxic gas generated in combustion, and potential and unknown dangers exist [ chemical. Ningbo material composite material green recovery research advances [ J ] novel chemical materials, 2013 (2): 168-168.].
Therefore, the development of a decomposable thermosetting resin system is an effective way for realizing recycling of waste thermosetting resin and adhesives, coating materials and composite materials thereof, and is also one of important directions for the development of the field of thermosetting resin.
The benzoxazine resin (BZ) is a novel thermosetting resin which is a compound containing a nitrogen-oxygen six-membered heterocycle obtained by condensation reaction of phenols, aldehydes and amine compounds serving as raw materials, and is cured to obtain the polybenzoxazine resin. Besides good heat resistance and flame retardance of the traditional phenolic resin, the benzoxazine resin has no volatile micromolecules released in the ring-opening curing process, the thermosetting shrinkage rate is nearly zero, the porosity of the cured polybenzoxazine resin is low, internal stress and cracks almost do not exist, and the benzoxazine resin is beneficial to processing and molding of finished products and maintaining the size of products. Meanwhile, benzoxazine resin almost has no free aldehyde and phenol, can be used as a flame retardant material of an engine room, and is widely applied to various fields of buildings, transportation, aerospace, electronics, ships, energy sources and the like [ guo army, domestic and foreign composite material waste recovery technology and development status [ J ] scientific and technological innovation guide, 2011 (33): 99-100.].
However, the crosslinked network structure of the benzoxazine resin after curing is insoluble and infusible, which greatly limits the application of the benzoxazine resin in the aspects of recycling and degradability. Therefore, the method for degrading and recycling the cured benzoxazine is important for recycling the composite material waste, building a resource-saving and environment-friendly harmonious society, and responding to the call of environment protection, energy conservation, emission reduction and sustainable development at home and abroad.
Therefore, a degradable benzoxazine resin is needed to realize the recycling and reusing of the benzoxazine resin.
Disclosure of Invention
In order to overcome the above problems, the present inventors have conducted intensive studies and, as a result, found that: the benzoxazine resin containing the spiro acetal structure is prepared from the bisphenol compound containing the spiro acetal structure, a primary amine compound and an aldehyde compound through a solution synthesis method, the cured product of the prepared benzoxazine resin after curing has good chemical degradation property, the recycling and reutilization of waste materials are realized, and the preparation method is simple in process, mild in condition and environment-friendly, and is beneficial to large-scale industrial production, so that the invention is completed.
The invention aims to provide a benzoxazine resin containing a spiro acetal structure, wherein the benzoxazine resin contains a structure shown in a formula (I):
a, B is independently selected from one of formula (II) to formula (IV), A and B can be same or different;
wherein R is1、R2、R3Each independently selected from H, alkyl, alicyclic group, aromatic group or derivatives thereof, R1、R2And R3May be the same or different.
Another aspect of the present invention is to provide a method for preparing a benzoxazine resin containing a spiro acetal structure, the method comprising the steps of:
step 2, adding an aldehyde compound into the system in the step 1 for reaction;
and 3, carrying out post-treatment on the product obtained in the step 2.
The invention further provides a decomposition method of the benzoxazine resin cured product containing the spiro acetal structure, and the benzoxazine resin cured product is soaked in an acid solution for 2-72 hours, preferably 8-48 hours.
The invention has the following beneficial effects:
(1) the benzoxazine resin containing the spiro acetal structure has the spiro structure, so that the benzoxazine resin has excellent rigidity and heat resistance;
(2) the cured product of the benzoxazine resin containing the spiro acetal structure has good chemical degradation property and can be degraded under an acidic condition, so that the cyclic utilization of a composite material product can be realized;
(3) according to the preparation method of the benzoxazine resin containing the spiro acetal structure, the prepared benzoxazine resin has high purity and high yield, and the yield can reach 80% or even 85%;
(4) the preparation method of the benzoxazine resin containing the spiro acetal structure provided by the invention has the advantages of simple process, mild conditions, easily available raw materials, environmental friendliness and capability of large-scale industrial production.
Drawings
FIG. 1 shows an IR spectrum of the product obtained in example 1 of the present invention; FIG. 2 shows the DSC curve of the product obtained in example 1 of the present invention; FIG. 3 shows the nuclear magnetic hydrogen spectrum of the product obtained in example 1 of the present invention; FIG. 4 shows an IR spectrum of the product obtained in example 8 of the present invention; FIG. 5 shows a DSC curve of the product obtained in example 8 of the present invention; FIG. 6 shows a nuclear magnetic hydrogen spectrum of a product obtained in example 8 of the present invention; FIG. 7 shows an IR spectrum of a product obtained in example 11 of the present invention; FIG. 8 shows a DSC curve of the product obtained in example 11 of the present invention; FIG. 9 shows a nuclear magnetic hydrogen spectrum of a product obtained in example 11 of the present invention; FIG. 10 shows an IR spectrum of a product obtained in example 12 of the present invention; FIG. 11 shows a DSC curve of the product obtained in example 12 of the present invention; FIG. 12 shows a nuclear magnetic hydrogen spectrum of a product obtained in example 12 of the present invention; FIG. 13 shows an IR spectrum of a product obtained in example 10 of the present invention; FIG. 14 shows a DSC curve of the product obtained in example 10 of the present invention; FIG. 15 shows a nuclear magnetic hydrogen spectrum of a product obtained in example 10 of the present invention; FIG. 16 shows an IR spectrum of a product obtained in example 13 of the present invention; FIG. 17 shows a DSC curve of the product obtained in example 13 of the present invention; FIG. 18 shows a nuclear magnetic hydrogen spectrum of a product obtained in example 13 of the present invention; FIG. 19 shows an IR spectrum of a product obtained in example 14 of the present invention; FIG. 20 shows a DSC curve of the product obtained in example 14 of the present invention; FIG. 21 shows a nuclear magnetic hydrogen spectrum of a product obtained in example 14 of the present invention; FIG. 22 shows an IR spectrum of a product obtained in example 15 of the present invention; FIG. 23 shows a DSC curve of the product obtained in example 15 of the present invention; FIG. 24 shows a nuclear magnetic hydrogen spectrum of a product obtained in example 15 of the present invention; FIG. 25 shows an IR spectrum of a product obtained in example 16 of the present invention; FIG. 26 shows an IR spectrum of a product obtained in example 17 of the present invention.
Detailed Description
The invention is explained in more detail below with reference to the drawings and preferred embodiments. The features and advantages of the present invention will become more apparent from the description.
According to an aspect of the invention, a benzoxazine resin containing a spiro acetal structure is provided, wherein the benzoxazine resin contains a structure shown in a formula (I)
A, B is independently selected from one of formula (II) to formula (IV), A and B can be same or different;
wherein R is1、R2、R3Each independently selected from H, alkyl, substituted alkyl, alicyclic group, aromatic group or derivatives thereof, R1、R2And R3May be the same or different.
According to the invention, alkyl is C1～C22Is preferably C1～C18More preferably methyl, ethyl, n-butyl, n-pentyl, n-hexyl, dodecyl or octadecyl, such as n-butyl, n-pentyl or n-hexyl.
According to the invention, the substituted alkyl is selected from benzyl or β -phenylethyl.
According to the invention, the cycloaliphatic radical is C3～C8Is preferably C3～C6Such as a cyclobutyl group, a cyclopentyl group or a cyclohexyl group, for example a cyclohexyl group.
According to the invention, the aryl is phenyl or substituted phenyl, the substituted phenyl is alkyl substituted phenyl or nitro substituted phenyl, and p-tolyl, o-tolyl or m-tolyl are preferred; the aryl derivative is selected from 3- (trifluoromethyl) phenyl.
In a particular embodiment according to the present invention, the benzoxazine resin containing a spiro acetal structure has a structure as shown in any one of the following (1) to (10),
(1) pentaerythritol bis-p-hydroxybenzaldehyde-aniline type
(2) Pentaerythritol bis-p-hydroxybenzaldehyde-cyclohexylamine type
(3) Pentaerythritol bis-p-hydroxybenzaldehyde-n-hexylamine type
(4) Pentaerythritol bis-p-hydroxybenzaldehyde-n-pentylamine type
(5) Pentaerythritol bis-p-hydroxybenzaldehyde n-butylamine type
(6) Pentaerythritol bis-m-hydroxybenzaldehyde-aniline type
(7) Pentaerythritol bis-m-hydroxybenzaldehyde-cyclohexylamine type
(8) Pentaerythritol bis-m-hydroxybenzaldehyde-n-hexylamine type
(9) Pentaerythritol bis-p-hydroxybenzaldehyde-dodecylamine type
(10) Pentaerythritol bis-p-hydroxybenzaldehyde-p-toluidine type
Another aspect of the present invention provides a method for preparing a benzoxazine resin containing a spiro acetal structure, preferably the above benzoxazine resin, comprising the steps of:
step 2, adding an aldehyde compound into the system in the step 1 for reaction;
and 3, carrying out post-treatment on the reaction product obtained in the step 2.
According to the present invention, in step 1, the bisphenol compound containing a spiro acetal structure is selected from one or more of pentaerythritol bis (p-hydroxybenzaldehyde), pentaerythritol bis (m-hydroxybenzaldehyde), pentaerythritol bis (o-hydroxybenzaldehyde) or their derivatives, preferably pentaerythritol bis (p-hydroxybenzaldehyde) or pentaerythritol bis (m-hydroxybenzaldehyde).
Wherein, the molecular structures of the pentaerythritol bis-p-hydroxybenzaldehyde, the pentaerythritol bis-m-hydroxybenzaldehyde and the pentaerythritol bis-o-hydroxybenzaldehyde are respectively shown as formula (V), formula (VI) and formula (VII).
According to the invention, in step 1, primary amine compounds such as alkylamine, substituted alkylamine, alicyclic amine, aromatic amine and derivatives thereof are used.
According to the invention, the alkylamine is a C1-C22 alkylamine, preferably a C1-C18 alkylamine, more preferably methylamine, ethylamine, n-propylamine, n-butylamine, n-pentylamine, n-hexylamine, dodecylamine or octadecylamine, for example n-butylamine, n-pentylamine or n-pentylamine.
According to the invention, the substituted alkylamine is selected from benzylamine or β -phenylethylamine.
According to the invention, the alicyclic amine is a C3-C8 alicyclic amine, preferably a C3-C6 alicyclic amine, more preferably a cyclobutane amine, a cyclopentan-amine or a cyclohexylamine, such as cyclohexylamine.
According to the invention, the aromatic amine is selected from aniline or substituted aniline, preferably aniline; and/or, the derivative of the aromatic amine is selected from 3- (trifluoromethyl) phenyl.
According to the invention, the substituted aniline is an alkyl-substituted aniline or a nitro-substituted aniline, preferably p-toluidine, o-toluidine or m-toluidine.
According to the present invention, in step 2, the aldehyde compound is paraformaldehyde or an aqueous formaldehyde solution, preferably paraformaldehyde.
In the invention, a bisphenol compound containing a spiro acetal structure, a primary amine compound and an aldehyde compound are subjected to condensation reaction to obtain the benzoxazine resin containing the spiro acetal structure, the synthesis method mainly comprises a solution method, a suspension method or a melting method, the benzoxazine resin is prepared by adopting a solution synthesis method, and phenolic hydroxyl, amino and aldehyde groups in the benzoxazine resin are reacted in the condensation reaction process, so that the amount of the bisphenol compound containing the spiro acetal structure, the primary amine compound and the aldehyde compound is calculated by the amount of the phenolic hydroxyl, the amino and the aldehyde compounds.
According to the invention, in the bisphenol compound, the primary amine compound and the aldehyde compound containing the spiro acetal structure, the ratio of the amount of the phenolic hydroxyl group, the amino group and the aldehyde group is 1: 1: (2.0-2.8), preferably 1: 2.0-2.4.
According to the present invention, in step 1, the solvent is selected from one of ethanol, methanol, isopropanol, butanol, tetrahydrofuran, dioxane, toluene, Dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP), preferably one of DMF, DMSO, NMP, more preferably DMF or NMP.
In the present invention, the bisphenol compound containing a spiro acetal structure and the primary amine compound are dissolved in a solvent and uniformly mixed, preferably, uniformly mixed by stirring. And then adding the aldehyde compound into the system in the step 1, wherein the reaction process for preparing the benzoxazine resin comprises an exothermic reaction, and in order to ensure that the reaction is sufficient and prevent other byproducts or exothermic reactions from being generated and influencing the yield of a final product, the aldehyde compound needs to be slowly added into the system in the step 1, and is preferably added into the system in the step 1 in portions.
According to the present invention, in step 2, the aldehyde compound is added to the system of step 1 one to many times, preferably 2 to 6 times, and more preferably 2 to 4 times.
According to the invention, because the early stage of the condensation reaction comprises an exothermic reaction, in order to prevent the heat released by the reaction from influencing the synthesis of a final product, the reaction system needs to be stirred at a low temperature of-10 ℃.
According to the invention, in the step 2, the reaction system is placed in a low-temperature constant-temperature water bath and stirred for 10-60 min, preferably 20-50 min, and more preferably 30 min.
According to the invention, in the step 2, the temperature of the reaction system is increased to carry out the reflux reaction at 80-120 ℃, preferably 90-110 ℃, more preferably 95-105 ℃, for example 95 ℃.
According to the invention, in the step 2, the temperature-rising reflux reaction time of the reaction system is 1-15 h, preferably 2-10 h, more preferably 5-12 h, most preferably 8-10 h, for example 10 h.
According to the invention, in step 3, the work-up comprises washing, filtering and drying of the reaction product obtained in step 2.
According to the invention, in the step 3, the reaction product obtained in the step 2 is washed by sodium hydroxide aqueous solution, filtered, washed by deionized water to be neutral and filtered, and the process can be repeated for multiple times, wherein the concentration of sodium hydroxide is preferably 1-3 mol/L.
According to the invention, in the step 3, the drying is to vacuum dry the washed and filtered product to constant weight, preferably the vacuum drying temperature is 40-60 ℃, preferably 50-60 ℃, for example 50 ℃.
In the present invention, the cured product can be prepared by curing the prepared benzoxazine resin containing a spiro acetal structure, and the preparation method preferably comprises the following steps: the benzoxazine resin containing the spiro acetal structure is treated for 2-16 hours at 100-240 ℃, preferably for 2-12 hours at 140-220 ℃, more preferably according to a programmed gradient temperature rise, and is treated for 1-2 hours at constant temperature of 140 ℃, 160 ℃, 180 ℃, 200 ℃ and 220 ℃.
In another aspect, the present invention provides a method for degrading a benzoxazine resin cured product containing a spiro acetal structure, the method specifically comprising: and (3) soaking the benzoxazine resin cured product containing the spiro acetal structure in an acid solution for 2-72 hours, preferably 8-48 hours.
According to the invention, the acidic solution comprises an acid compound, and the acid compound is an organic acid or an inorganic acid.
According to the invention, the organic acid is selected from one or more of formic acid, acetic acid, p-toluenesulfonic acid, trifluoromethanesulfonic acid and trichloroacetic acid, preferably acetic acid or p-toluenesulfonic acid, and more preferably acetic acid.
According to the invention, the inorganic acid is selected from one or more of hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid.
According to the invention, the acidic solution also comprises a polar solvent, preferably water, alcohol compounds, ketone compounds, ether compounds or amide compounds,
according to the invention, the alcohol compound is a compound containing one or more hydroxyl groups, and is selected from 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, preferably methanol, ethanol, ethylene glycol, or diethylene glycol, more preferably ethanol or diethylene glycol.
According to the invention, the ketone compound is selected from butanone or cyclohexanone.
According to the invention, the ether compound is one or more selected from ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, Tetrahydrofuran (THF) and 1, 4-dioxane, preferably THF or 1, 4-dioxane.
According to the invention, the amide compound is selected from one of Dimethylformamide (DMF), dimethyl sulfoxide (DMSO), sulfolane, N-methyl pyrrolidone (NMP), morpholine and N-methyl morpholine, preferably one or more of DMF, DMSO and NMP, preferably DMF or DMSO.
The benzoxazine resin containing the spirocyclic acetal structure provided by the invention is mixed with other thermosetting resins to obtain a composition, wherein the other thermosetting resins comprise one or more of epoxy resin, polyurethane resin, cyanate resin, furan resin, phenolic resin, unsaturated polyester resin, bismaleimide resin and other benzoxazine resin.
The benzoxazine resin containing the spiro acetal structure can be used for preparing various compositions with reinforcing materials, such as silicon dioxide, carbon nanotubes, glass fibers, carbon fibers, aramid fibers and the like, so as to obtain thermosetting resins with different purposes and products thereof. The obtained product has low porosity, small volume shrinkage, excellent heat resistance and mechanical property.
Examples
The invention is further described below by means of specific examples. However, these examples are only illustrative and do not limit the scope of the present invention.
The following examples and comparative examples employ test methods:
infrared spectroscopy test (FTIR): an IS-5 Fourier infrared spectrometer, wherein a KBr tabletting method IS adopted to prepare a test sample;
nuclear magnetic resonance hydrogen spectrum test (1H-NMR): adopting a 400MHz nuclear magnetic resonance instrument of Bruker Avance, wherein the testing temperature is 25 ℃, and the solvent is deuterated chloroform;
differential Scanning Calorimeter (DSC): model TQ100, test conditions: the temperature was raised from room temperature to 350 ℃ at a temperature raising rate of 10 ℃/min under a nitrogen atmosphere.
Example 1
Weighing raw materials according to the molar ratio of phenolic hydroxyl group, amino group and aldehyde group of 1: 2.1, sequentially adding 50mL of DMF, 3.44g (0.01mol) of pentaerythritol bis-p-hydroxybenzaldehyde and 1.83mL (0.02mol) of aniline into a 100mL three-neck flask, and uniformly stirring and mixing;
adding 1.261g (0.042mol) of paraformaldehyde into a three-neck flask for 2-4 times, placing the three-neck flask in a low-temperature constant-temperature reaction bath, stirring for 30min, gradually heating to 95 ℃, and reacting at constant temperature for 10 h.
After the reaction is finished, washing a reaction product by using a sodium hydroxide aqueous solution with the concentration of 1mol/L, filtering, washing by using deionized water to be neutral, filtering, and drying in vacuum at 50 ℃ to be constant weight.
The final product was weighed and the calculated yield was 40.1%.
And performing infrared and DSC tests and nuclear magnetic characterization on the obtained final product, wherein the obtained infrared spectrogram, DSC curve and nuclear magnetic hydrogen spectrum are respectively shown in figure 1, figure 2 and figure 3.
In FIG. 1, at 1600cm-1And 1501cm-1The position is a stretching vibration peak of C-C on a benzene ring. At 1242cm-1And 1031cm-1And asymmetric stretching vibration peaks and symmetric stretching vibration peaks of C-O-C bonds on the oxazine ring are respectively formed. At 947cm-1The absorption vibration peak of the oxazine ring is shown. And 1077cm-1And 824cm-1The peak is the peak of C-O-C vibration on the acetal ring, except for 824cm-1And the position is also the vibration peak of C-N-C on the oxazine ring. In conclusion, the final product contains a spiro acetal structure and oxazine rings in the molecular structure.
As can be seen from FIG. 2, the first downward peak on the DSC curve is the melting endothermic peak, and the melting peak top temperature is about 155 ℃. The second upward peak is the exothermic curing peak of the oxazine, the initial curing temperature of the pentaerythritol bis-p-hydroxybenzaldehyde-aniline oxazine is 180 ℃, and the peak top temperature is about 227 ℃. Around 290 c, a downward endothermic peak begins to appear, probably because the oxazine ring is decomposed at high temperature.
In fig. 3, a proton peak H newly appears at a chemical shift δ of 4.60ppmaBelonging to the hydrogen on the middle carbon of the oxazine ring N-C-C structure. Chemical shift δ 538ppm belongs to the proton peak HbAnd HcCorresponding peak area Sb+c∶SaThe ratio of the corresponding hydrogen is also satisfied at 3: 2. Chemical shifts at four positions of d, e, f and g on the intermediate spiro structure are also changed from 4.5ppm-3.6ppm to 4.9ppm-3.6ppm, and the chemical shifts of two kinds of hydrogen are overlapped. Integral integration Sa: S for some peaksb+c∶Sd∶Se∶Sf∶Sg∶Sh+i+j+k+1+m2: 3: 1: 8, in accordance with the theoretical hydrogen ratios at the individual positions. As a result, the final product obtained was pentaerythritol bis-p-hydroxybenzaldehyde-aniline oxazine (solvent peak of deuterated chloroform at δ 7.29 ppm), and had high purity.
Example 2
The procedure of example 1 was repeated except that paraformaldehyde was added in an amount of 1.321g (0.044mol), that is, a molar ratio of phenolic hydroxyl group, amine group and aldehyde group was 1: 2.2, and the obtained yield was 77.6%. The resulting final product was subjected to infrared, DSC testing and nuclear magnetic characterization, and the results were similar to example 1.
Example 3
The procedure of example 1 was repeated except that paraformaldehyde was added in an amount of 1.381g (0.046mol), that is, a molar ratio of phenolic hydroxyl group, amine group and aldehyde group was 1: 2.3, and the obtained yield was 85%. The resulting final product was subjected to infrared, DSC testing and nuclear magnetic characterization, and the results were similar to example 1.
Example 4
The procedure of example 1 was repeated except that paraformaldehyde was added in an amount of 1.201g (0.04mol), that is, a molar ratio of phenolic hydroxyl group, amine group and aldehyde group was 1: 2.0, and the obtained yield was 35%. The resulting final product was subjected to infrared, DSC testing and nuclear magnetic characterization, and the results were similar to example 1.
Example 5
The procedure of example 1 was repeated except that paraformaldehyde was added in an amount of 1.441g (0.048mol), that is, a molar ratio of phenolic hydroxyl group, amine group and aldehyde group was 1: 2.4, and the obtained yield was 80%. The resulting final product was subjected to infrared, DSC testing and nuclear magnetic characterization, and the results were similar to example 1.
Example 6
The procedure in example 3 was repeated, except that the isothermal reaction time was 6h, and the yield was 80.7%. The resulting final product was subjected to infrared, DSC testing and nuclear magnetic characterization, and the results were similar to example 1.
Example 7
The procedure in example 3 was repeated, except that the isothermal reaction time was 2h, and the yield was 35.3%. The resulting final product was subjected to infrared, DSC testing and nuclear magnetic characterization, and the results were similar to example 1.
Example 8
Weighing raw materials according to the molar ratio of phenolic hydroxyl group, amino group and aldehyde group of 1: 2.3, sequentially adding 50ml of mixed solution of LDMF, 3.44g (0.01mol) of pentaerythritol bis-p-hydroxybenzaldehyde and 2.30ml (0.02mol) of cyclohexylamine into a 100ml three-neck flask, and uniformly stirring and mixing;
adding 1.381g (0.046mol) of paraformaldehyde into a three-neck flask 2-4 times, placing the three-neck flask in a low-temperature constant-temperature reaction bath, stirring for 30min, gradually heating to 95 ℃, and reacting at constant temperature for 10 h.
After the reaction is finished, washing a reaction product by using a sodium hydroxide aqueous solution with the concentration of 1mol/L, filtering, washing by using deionized water to be neutral, filtering, and drying in vacuum at 50 ℃ to be constant weight.
The final product was weighed and the calculated yield was 33.2%.
And performing infrared and DSC tests and nuclear magnetic characterization on the obtained final product, wherein the obtained infrared spectrogram, DSC curve and nuclear magnetic hydrogen spectrum are respectively shown in figure 4, figure 5 and figure 6.
As can be seen in FIG. 4, 1504cm-1The single peak is the stretching vibration peak of C-C on the benzene ring, 1230cm-1The position is a stretching vibration peak of a C-O-C bond on the oxazine ring; 891cm-1Is treated as the absorption vibration peak of oxazine ring, 823cm-1And 1075cm-1Is a stretching vibration peak of C-O-C on an acetal ring; in addition, 823cm-1Is also the oscillation peak of C-N-C on the oxazine ring; in conclusion, the final product contains a spiro acetal structure and oxazine rings in the molecular structure.
As can be seen in fig. 5, the first downward peak is the melting endotherm and the melting peak top temperature is around 186 ℃. The second upward peak is the exothermic curing peak of the oxazine, the initial curing temperature of the pentaerythritol bis-p-hydroxybenzaldehyde-cyclohexylamine oxazine is about 190 ℃, and the peak top temperature is about 245 ℃. Around 278 ℃, a downward endothermic peak begins to appear, and the peak is broad, probably because the oxazine is decomposed at high temperature.
As can be seen from fig. 6, a proton peak H newly appears at a chemical shift δ of 4.13ppmaBelonging to the hydrogen on the middle carbon of the oxazine ring N-C-C structure; the chemical shift delta is 5.39ppm and is the proton peak HcAnd the peak at 5.01ppm is the proton peak Hb(ii) a Chemical shifts at four positions of d, e, f and g on the intermediate spiro structure are also changed from 4.5ppm-3.6ppm to 4.9ppm-3.6ppm, and the chemical shifts of two kinds of hydrogen are overlapped. And belongs to the proton peak H on cyclohexylaminekTo HpIt is in the range of 2.7ppm to 1.1 ppm. Proton peaks on cyclohexylamine are not easy to be scored separately, and some peaks are integrated to obtain Sa∶Sb∶Sc∶Sd∶Se∶Sf∶Sg∶Sh∶Si∶Sj：Sk+1+m+n+o+p2: 1: 11, in accordance with the theoretical ratio of hydrogen in each position. In conclusion, the pentaerythritol bis-p-hydroxybenzaldehyde-cyclohexylamine oxazine is determined to be synthesized.
Example 9
Weighing the raw materials according to the molar ratio of phenolic hydroxyl group, amino group and aldehyde group of 1: 2.3, sequentially adding 50mL of dioxane, 3.44g (0.01mol) of pentaerythritol bis-p-hydroxybenzaldehyde and 2.30mL (0.02mol) of cyclohexylamine into a 100mL three-neck flask, and stirring and uniformly mixing;
adding 1.381g (0.046mo1) of paraformaldehyde into a three-neck flask 2-4 times, placing the three-neck flask in a low-temperature constant-temperature reaction bath, stirring for 30min, gradually heating to 95 ℃, and reacting at constant temperature for 10 h.
After the reaction is finished, washing a reaction product by using a sodium hydroxide aqueous solution with the concentration of 1mol/L, filtering, washing by using deionized water to be neutral, filtering, and drying in vacuum at 50 ℃ to be constant weight. The calculated yield was 54.3%.
Example 10
The procedure in example 9 was repeated except that 1.977ml (0.02mol) of n-butylamine was used in place of 2.30ml (0.02mol) of cyclohexylamine, to calculate the yield to be 43.1%.
And performing infrared and DSC tests and nuclear magnetic characterization on the obtained final product, wherein the obtained infrared spectrogram, DSC curve and nuclear magnetic hydrogen spectrum are respectively shown in figure 13, figure 14 and figure 15.
As can be seen from FIG. 13, 1504cm-1Is at 1232cm, and has a C-C stretching vibration peak on benzene ring-1The position is a stretching vibration peak of a C-O-C bond on the oxazine ring. 923cm-1Is positioned at the absorption vibration peak of oxazine ring of 824cm-1And 1079cm-1Is a stretching vibration peak of C-O-C on an acetal ring, and is 824cm-1And is also the oscillation peak of C-N-C on the oxazine ring. At 2947cm-1And 2856cm-1In the form of CH carried on n-butylamine2、CH3The peak of vibration of (1). Thus, as can be seen in fig. 13, there is the generation of oxazines.
As can be seen in FIG. 14, the first downward peak is the melting endotherm and the melting peak top temperature is around 107 ℃. The second upward peak is the exothermic curing peak of oxazine, which has an initial curing temperature of about 150 deg.C and a peak top temperature of about 228 deg.C. Around 255 ℃, a downward endothermic peak begins to appear, and the oxazine is decomposed probably at high temperature.
As can be seen from fig. 15, what appears at δ ═ 4.02pm is the proton peak Ha, which belongs to the hydrogen on the middle carbon of the oxazine ring N-C structure. The proton peak Hc is at 5.39ppm, and the proton peak Hb appears at 4.86 ppm. Chemical shifts of four positions of d, e, f and g on the intermediate spiro structure are changed to 4.9ppm-3.6ppm, and some proton peaks and HbAn overlap occurs. Proton peak H on n-butylaminekTo HoIt is in the range of 0.9ppm to 2.9 ppm. Integrating the peak area to obtain Sa∶Sb∶Sc∶Sd+e+f+g∶Sh∶Si∶Sj∶Sk∶Sl∶Sm∶Sn2: 1: 4.6: 1: 2: 2.2: 3.2, slightly different from the theoretical hydrogen ratios, probably because of the long reaction time, which leads to the ring opening of partial oxazines. In conclusion, the obtained final product is pentaerythritol bis (p-hydroxybenzaldehyde) -n-butylamine type oxazine and has high purity.
Example 11
The procedure in example 9 was repeated except that 2.642ml (0.02mol) of n-hexylamine was used in place of 2.30ml (0.02mol) of cyclohexylamine, and the calculated yield was 22.6%.
And performing infrared and DSC tests and nuclear magnetic characterization on the obtained final product, wherein the obtained infrared spectrogram, DSC curve and nuclear magnetic hydrogen spectrum are respectively shown in figure 7, figure 8 and figure 9.
As can be seen from FIG. 7, 1504cm-1Is positioned at 1231cm which is a C-C stretching vibration peak on a benzene ring-1The position is a stretching vibration peak of a C-O-C bond on the oxazine ring; 929cm-1The absorption vibration peak of the oxazine ring is shown. 824cm-1And 1077cm-1Is a stretching vibration peak of C-O-C on an acetal ring, and further, 824cm-1Is also the oscillation peak of C-N-C in the oxazine ring; 929cm-1What appears here is the vibrational peak of the benzene ring to which the oxazine ring is attached. Thus illustrating the presence of an oxazine ring.
As can be seen from FIG. 8, the first downward peak is the melting endotherm and the melting peak top temperature is around 105 ℃. The second upward peak is the exothermic curing peak of the oxazine, the initial curing temperature of the pentaerythritol bis-p-hydroxybenzaldehyde-n-hexylamine oxazine is about 155 ℃, and the peak top temperature is about 240 ℃. After which no endothermic peak appeared.
As can be seen from fig. 9, what appears at δ of 4.02ppm is the proton peak HaBelonging to the hydrogen on the middle carbon of the oxazine ring N-C-C structure. Delta 5.39ppmIs proton peak HcProton peak HbOccurs at δ 4.89 ppm; chemical shifts of four positions of d, e, f and g on the intermediate spiro structure are also changed from 4.5ppm-3.6ppm to 4.9ppm-3.6ppm, and some proton peaks and HbAn overlap occurs. Belonging to the proton peaks Hk to H on n-hexylaminepIt is in the range of 0.89ppm to 2.75 ppm. Integration of peak area to obtain Sa∶Sb∶Sc∶Sd∶Se∶Sf∶Sg∶Sh∶Si∶Sj∶Sk∶Sl：Sm+n+o：Sp2: 1: 2: 6: 3.2, except for HpThe peak area of (A) is slightly larger, and the other parts are consistent with the proportion of hydrogen at each theoretical position. In conclusion, the obtained final product is pentaerythritol bis (p-hydroxybenzaldehyde) -n-hexylamine oxazine.
Example 12
The procedure in example 9 was repeated except that 2.32ml (0.02mol) of n-pentylamine was used in place of 2.30ml (0.02mol) of cyclohexylamine, and the calculated yield was 56.6%.
And performing infrared and DSC tests and nuclear magnetic characterization on the obtained final product, wherein the obtained infrared spectrogram, DSC curve and nuclear magnetic hydrogen spectrum are respectively shown in figure 10, figure 11 and figure 12.
As can be seen from FIG. 10, 1504cm-1Is the stretching vibration peak of C-C on the benzene ring at 1230cm-1The position is a stretching vibration peak of a C-O-C bond on the oxazine ring. 929cm-1The absorption vibration peak of the oxazine ring is shown. 824cm-1And 1079cm-1The peak is the stretching vibration peak of C-O-C on the acetal ring, and the peak is 824cm-1Is also the oscillation peak of C-N-C in the oxazine ring. At 2941cm-1And 2858cm-1In the form of CH carried by n-pentylamine2、CH3The peak of vibration of (1). Thus, as can be seen in fig. 10, there is the generation of oxazines.
As can be seen from FIG. 11, the first downward peak is the melting endotherm and the melting peak top temperature is around 113 ℃. The second upward peak is the exothermic curing peak of the oxazine, the initial curing temperature of the pentaerythritol bis-p-hydroxybenzaldehyde-n-pentylamine oxazine is about 155 ℃, and the peak top temperature is about 240 ℃. Around 286 c, a downward endothermic peak begins to appear, probably because at high temperatures, oxazines decompose.
As can be seen from fig. 12, what appears at δ ═ 4.01ppm is the proton peak Ha, which is the hydrogen on the middle carbon of the oxazine ring N-C structure. The chemical shift δ of 5.38ppm is the proton peak Hc, and the proton peak Hb appears at δ of 4.88 ppm. Since an oxazine ring is formed, the chemical shifts and splits of the hydrogens on the benzene ring are changed, and the proton peaks Hj, Hh, and Hi all appear in the chemical shift δ range of 6.77ppm to 7.29 ppm. In addition, chemical shifts at four positions of d, e, f and g on the intermediate spiro structure are changed from 4.5ppm-3.6ppm to 4.9ppm-3.6ppm, and some proton peaks are overlapped with Hb. Belongs to the proton peak H on n-pentylaminekTo HoIt is in the range of 0.9ppm to 2.9 ppm. Integrating the peak area to obtain Sa∶Sb∶Sc∶Sd+e+f+g∶Sh∶Si∶Sj∶Sk∶Sl+m+n∶SoThe ratio of hydrogen in each position is theoretically the same as 2: 1: 4: 1: 2: 6: 3. In conclusion, the obtained final product is pentaerythritol bis (p-hydroxybenzaldehyde) -n-pentylamine oxazine and has high purity.
Example 13
Weighing raw materials according to the molar ratio of phenolic hydroxyl group, amino group and aldehyde group of 1: 2.3, sequentially adding 50mL of dioxane, 3.44g (0.01mol) of pentaerythritol bis-m-hydroxybenzaldehyde and 1.83mL (0.02mol) of aniline into a 100mL three-neck flask, and uniformly stirring and mixing;
adding 1.381g (0.046mol) of paraformaldehyde into a three-neck flask 2-4 times, placing the three-neck flask in a low-temperature constant-temperature reaction bath, stirring for 30min, gradually heating to 95 ℃, and reacting at constant temperature for 10 h.
After the reaction is finished, washing a reaction product by using a sodium hydroxide aqueous solution with the concentration of 1mol/L, filtering, washing by using deionized water to be neutral, filtering, and drying in vacuum at 50 ℃ to be constant weight. The calculated yield was 23.4%.
And performing infrared and DSC tests and nuclear magnetic characterization on the obtained final product, wherein the obtained infrared spectrogram, DSC curve and nuclear magnetic hydrogen spectrum are respectively shown in figure 16, figure 17 and figure 18.
From FIG. 16, it can be seen that it is at 1599cm-1And 1498cm-1The position is the stretching vibration peak of C-C on the benzene ring. 1229cm-1And 1032cm-1And asymmetric stretching vibration peaks and symmetric stretching vibration peaks of C-O-C bonds on the oxazine ring are respectively formed. 932cm-1The absorption vibration peak of the oxazine ring is shown. 1078cm-1And 803cm-1The peak is a stretching vibration peak of C-O-C on the acetal ring, except for 803cm-1And the position is also the vibration peak of C-N-C in the oxazine ring. The molecular structure of the final product contains a spiro acetal structure and an oxazine ring.
From FIG. 17, it can be seen that two melting peaks appear, the first melting peak having a peak top temperature of about 130 ℃ and the second melting peak having a peak top temperature of 190 ℃. The third upward peak is the exothermic curing peak of oxazine, the initial curing temperature is about 230 ℃, and the peak top temperature is about 260 ℃. Around 295 c, a small endothermic peak appears, probably because at high temperatures partial decomposition of oxazines occurs.
As can be seen from fig. 18, the newly appearing proton peak Ha at δ ═ 4.65ppm belongs to the hydrogen on the middle carbon of the oxazine ring N-C structure. The peak area is 5.38ppm, belonging to proton peaks Hb and Hc, corresponding to peak area Sb+c∶SaThe ratio of the corresponding hydrogen is also satisfied at 3: 2. Because the oxazine ring is generated, the chemical shift and split of hydrogen on the original benzene ring are changed, and in addition, the benzene ring brought by aniline on the oxazine ring, proton peaks of hydrogen on all the benzene rings are in the range of chemical shift delta being 6.95-7.3ppm, and the phenomenon of chemical shift overlapping occurs. In addition, chemical shifts at four positions of d, e, f and g on the intermediate spiro structure are changed from 4.5ppm-3.6ppm to 4.85ppm-3.6ppm, and the chemical shifts of two kinds of hydrogen are overlapped. The integration of the peak areas is performed for FIGS. 3-18, with some of the peaks being rounded due to the similarity and partial overlap of the chemical shifts of the hydrogens and some of the hydrogens on the phenyl ringsVolume fraction Sa∶Sb+c∶Sd∶Se∶Sf∶SgThe ratio of hydrogen is 2: 3: 1, which is consistent with the theoretical ratio of hydrogen at each position. The interval of the hydrogen on the benzene ring is difficult to integrate because of too many hetero peaks. From the figure, we can find more small peaks, namely the acetal of the raw material is not removed, or ring-opening polymerization reaction of the oxazine is carried out, but the synthesis of pentaerythritol bis-m-hydroxybenzaldehyde-aniline type oxazine can be determined.
Example 14
The procedure in example 13 was repeated, except that 2.30ml (0.02mol) of cyclohexylamine was used in place of 1.83ml (0.02mol) of aniline, to give a yield of 68.8%.
And performing infrared and DSC tests and nuclear magnetic characterization on the obtained final product, wherein the obtained infrared spectrogram, DSC curve and nuclear magnetic hydrogen spectrum are respectively shown in figure 19, figure 20 and figure 21.
As can be seen from FIG. 19, 1247cm-1And the position is a stretching vibration peak of a C-O-C bond on the oxazine ring. At 924cm-1Is the absorption vibration peak belonging to oxazine ring, and 1079cm-1Is the stretching vibration peak of C-O-C on the acetal ring, 873cm-1The peak is the vibration peak of C-N-C in the oxazine ring. 2928cm-1And 2852cm-1In the presence of CH carried by cyclohexylamine2The peak of vibration of (1). The molecular structure of the final product contains a spiro acetal structure and an oxazine ring.
From FIG. 20, it can be seen that the first downward melting peak top temperature is around 148 ℃. The first upward peak is the exothermic curing peak of oxazine, which has an initial curing temperature of about 185 deg.C and a peak top temperature of about 242 deg.C. At around 270 ℃, an endothermic peak appears, probably because partial decomposition of oxazines occurs at high temperatures.
As can be seen from fig. 21, the newly-appearing proton peak Ha at δ ═ 4.10ppm belongs to the hydrogen on the middle carbon of the oxazine ring N-C structure. The proton peak Hc is at 5.38ppm δ, and the proton peak Hb is at 5.00ppm δ. Because oxazine rings are generated, chemical shifts and splits of hydrogen on the original benzene ring are changed, and proton peaks Hh, Hi and Hj all appear in a chemical shift delta range of 6.76-7.29 ppm. Chemical shifts of four positions of d, e, f and g on the intermediate spiro structure are also changed to 4.9ppm-3.6 ppm. And the proton peaks Hk to Hp belonging to cyclohexylamine appear in the interval of 2.7ppm to 1.1 ppm. In the figure, we can find that the peak is much, the raw material is not removed completely, or the reaction time is too long to cause partial ring opening of oxazine, and the acetal of m-hydroxyl has two reaction sites and byproducts. The method can ensure that the pentaerythritol bis-m-hydroxybenzaldehyde-cyclohexylamine oxazine is successfully synthesized.
Example 15
The procedure in example 13 was repeated except that 2.64ml (0.02mol) of n-hexylamine was used in place of 1.83ml (0.02mol) of aniline, to obtain a yield of 35.6%.
And performing infrared and DSC tests and nuclear magnetic characterization on the obtained final product, wherein the obtained infrared spectrogram, DSC curve and nuclear magnetic hydrogen spectrum are respectively shown in figure 22, figure 23 and figure 24.
As can be seen in FIG. 22, at 1244cm-1 is the stretching vibration peak of the C-O-C bond on the oxazine ring. At 931cm-1The absorption vibration peak of 1072cm is the absorption vibration peak of oxazine ring-1(iii) a stretching vibration peak of 879cm at C-O-C of acetal ring-1The peak is the vibration peak of C-N-C on the oxazine ring. 2929cm-1And 2856cm-1Where is CH carried by n-hexylamine2、CH3The peak of vibration of (1). Therefore, as can be seen from fig. 22, an oxazine ring is generated.
It can be seen from FIG. 23 that the first downward melting peak has a peak top temperature of about 86 deg.C, the second downward melting peak has a peak top temperature of 190 deg.C, an initial solidification temperature of about 225 deg.C, and a peak top temperature of about 249 deg.C.
As can be seen from fig. 24, the proton peak Ha appears at 6 ═ 4.00 ppm. The chemical shift δ is 5.39ppm, the proton peak Hc, and the chemical shift δ is 4.88ppm, the proton peak Hb. Because oxazine rings are generated, chemical shifts and splits of hydrogen on the original benzene ring are changed, and proton peaks Hh, Hi and Hj all appear in a chemical shift delta range of 6.76-7.00 ppm. Chemical shifts of four positions of d, e, f and g on the intermediate spiro structure are also changed to 4.9ppm-3.6 ppm. While the proton peak belonging to n-hexylamine appears in the interval of 2.7ppm to 0.9 pm. FIG. 24 was integrated Sa: Sb: Sc: Sd + e + f + g: Sh + i + j 2: 3: 1, in accordance with the theoretical ratio. More hetero-peaks can be found in the figure, which may be the partial ring opening of oxazines caused by too long reaction time or the by-products caused by two reaction sites of m-hydroxy acetal. The successful synthesis of pentaerythritol bis-m-hydroxybenzaldehyde-n-hexylamine oxazine can be determined.
Example 16
The procedure in example 9 was repeated except that 3.707g (0.02mol) of dodecylamine was used in place of 2.30ml (0.02mol) of cyclohexylamine, the yield was 40.3%. The obtained product was subjected to infrared test, and the results are shown in fig. 25.
As can be seen from FIG. 25, 1504cm-1The position is a C-C stretching vibration peak on a benzene ring; 1238cm-1The position is a stretching vibration peak of C-O-C on the oxazine ring; 918cm-1The peak is the absorption vibration peak of the oxazine ring; 1072cm-1And 829cm-1Is a stretching vibration peak of C-O-C on an acetal ring; further, 829cm-1And the position is also the vibration peak of C-N-C on the oxazine ring. 2924cm-1And 2850cm-1In the form of CH carried on dodecylamine2、CH3The peak of vibration of (1). As can be seen, an oxazine ring is present. The synthesis of pentaerythritol bis-p-hydroxybenzaldehyde-dodecylamine benzoxazine is illustrated.
Example 17
The synthesis was carried out in the same manner as in example 9 except that 2.143g (0.02mol) of p-toluidine was used in place of 2.30ml (0.02mol) of cyclohexylamine, giving a yield of 30.9%. The obtained product was subjected to infrared test, and the results are shown in fig. 25.
As can be seen in FIG. 26, 1518cm-1The position is a C-C stretching vibration peak on a benzene ring; 1238cm-1The position is a stretching vibration peak of C-O-C on the oxazine ring; 949cm-1The peak is the absorption vibration peak of the oxazine ring; 1072cm-1And 814cm-1Is a stretching vibration peak of C-O-C on an acetal ring; 879cm-1The peak is the vibration peak of C-N-C on the oxazine ring. 2858cm-1In the form of CH carried on p-toluidine3The peak of vibration of (1). As can be seen, an oxazine ring is present. The synthesis of pentaerythritol bis p-hydroxybenzaldehyde-p-toluidine benzoxazine is illustrated.
Comparative example 1
Weighing raw materials according to the molar ratio of phenolic hydroxyl group, amino group and aldehyde group of 1: 2.1, sequentially adding 50mL of toluene, 2.28g (0.01mol) of bisphenol A and 1.83mL (0.02mol) of aniline into a 100mL three-neck flask, and uniformly stirring and mixing;
adding 1.261g (0.042mol) of paraformaldehyde into a three-neck flask for 2-4 times, placing the three-neck flask in a low-temperature constant-temperature reaction bath, stirring for 30min, gradually heating to 95 ℃, and reacting at constant temperature for 10 h.
After the reaction is finished, the reaction product is washed by sodium hydroxide aqueous solution with the concentration of 1mol/L, filtered, washed by deionized water to be neutral, filtered and dried in vacuum at the temperature of 50 ℃ to be constant weight. The final product was weighed to give a yield of 75.2%.
And (3) curing the obtained final product, specifically, respectively carrying out constant temperature treatment for 1h at 140 ℃, 160 ℃, 180 ℃ and 200 ℃ according to the programmed temperature rise, and naturally cooling to the room temperature after the constant temperature treatment to obtain the cured product.
Examples of the experiments
Experimental example 1
Comparative example 1 the cured product and the cured product of example 1 were placed in an acidic solution, degraded by heating for a certain period of time, filtered, dried to a constant weight, and tested for the degree of degradation, with the results shown in table 1. Wherein the content of the first and second substances,
TABLE 1 degradation of the cured products of comparative example 1 and example 1 in acidic solution
| Sample (I) | Kinds of solution (volume ratio) | Temperature/. degree.C | Reaction time/h | Degree of degradation/%) |
| Comparative example 1 | Ethanol, water and acetic acid are 1: 1 | 85 | 9 | 0 |
| Example 1 | Ethanol, water and acetic acid are 1: 1 | 85 | 9 | 54.1 |
| Example 1 | Ethanol, water and acetic acid are 1: 1 | 85 | 24 | 81.2 |
| Example 1 | Ethanol, water and acetic acid are 1: 1 | 85 | 48 | 90 |
| Example 1 | Ethanol, water and acetic acid are 1: 2 | 85 | 48 | 100 |
| Example 1 | 50ml of ethanol: 0.025mol of p-toluenesulfonic acid | 85 | 9 | 52.3 |
| Example 1 | Nitric acid, water, DMF and ethanol in the ratio of 1 to 2 | 75 | 12 | 60.0 |
| Example 1 | Sulfuric acid, water, DMF and ethanol in the ratio of 1 to 2 | 65 | 12 | 16.5 |
| Example 1 | Ethanol, water and hydrochloric acid are 1: 2 | 85 | 8 | 60.2 |
| Example 1 | Glycol, water and acetic acid are 1: 1 | 100 | 10 | 65.2 |
| Example 1 | Diethylene glycol, water and acetic acid are 1: 1 | 100 | 10 | 63.5 |
| Example 1 | DMSO, water and acetic acid are 1: 2 | 120 | 48 | 100 |
| Example 1 | NMP, water and acetic acid are 1: 2 | 120 | 48 | 100 |
| Example 1 | THF, ethanol, water and acetic acid are 1: 2 | 60 | 48 | 55.7 |
As can be seen from table 1, the cured products of comparative example 1 and example 1 were placed in a solution of ethanol, water and acetic acid in a volume ratio of 1: 1, and after degradation at the same temperature for the same time, the degree of degradation of the cured product of comparative example 1 was 0, i.e., no degradation occurred, and the degree of degradation of the cured product of example 1 was 54.1%. The spirocyclic acetal structure is demonstrated to endow the polybenzoxazine resin with degradability under acidic conditions. As can be seen from Table 1, the cured products of example 1 were degraded to different degrees in the above solutions, and the longer the degradation time and the stronger the acidity, the higher the degradation degree, at the same solution and temperature. The cured product of the benzoxazine resin containing the helical acetal structure can be degraded under acidic conditions, and has the property of chemical degradation, namely the polybenzoxazine resin containing the helical acetal structure can be recycled.
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 only 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 (8)
1. A preparation method of benzoxazine resin containing a spiro acetal structure is characterized in that the benzoxazine resin contains a structure shown in a formula (I):
wherein A, B is independently selected from one of formula (II) to formula (IV), A and B are the same;
wherein R is1、R2、R3Each independently selected from alkyl, alicyclic or aromatic groups, R1、R2And R3In the same way, the first and second,
the alkyl is n-butyl, n-pentyl, n-hexyl or dodecyl; and
the alicyclic group is cyclohexane; and
the aryl is phenyl or p-tolyl;
the method comprises the following steps:
step 1, adding a bisphenol compound containing a spiro acetal structure and a primary amine compound into a solvent, and mixing;
step 2, adding an aldehyde compound into the system in the step 1 for reaction;
step 3, carrying out post-treatment on the product obtained in the step 2;
the bisphenol compound containing the spirocyclic acetal structure is selected from pentaerythritol bis-p-hydroxybenzaldehyde or pentaerythritol bis-m-hydroxybenzaldehyde,
the primary amine compound is alkylamine, alicyclic amine or aromatic amine,
the alkylamine is n-butylamine, n-pentylamine, n-hexylamine or dodecylamine,
the alicyclic amine is cyclohexylamine,
the aromatic amine is aniline or p-toluidine;
the aldehyde compound is paraformaldehyde or a formaldehyde aqueous solution;
in the bisphenol compound, the primary amine compound and the aldehyde compound containing the spiro acetal structure, the ratio of the amount of phenolic hydroxyl, amino and aldehyde is 1: 1: (2.0-2.4).
2. The method according to claim 1, wherein the benzoxazine resin has a structure as shown in any one of (1) to (10),
(1) pentaerythritol bis-p-hydroxybenzaldehyde-aniline type
(2) Pentaerythritol bis-p-hydroxybenzaldehyde-cyclohexylamine type
(3) Pentaerythritol bis-p-hydroxybenzaldehyde-n-hexylamine type
(4) Pentaerythritol bis-p-hydroxybenzaldehyde-n-pentylamine type
(5) Pentaerythritol bis-p-hydroxybenzaldehyde n-butylamine type
(6) Pentaerythritol bis-m-hydroxybenzaldehyde-aniline type
(7) Pentaerythritol bis-m-hydroxybenzaldehyde-cyclohexylamine type
(8) Pentaerythritol bis-m-hydroxybenzaldehyde-n-hexylamine type
(9) Pentaerythritol bis-p-hydroxybenzaldehyde-dodecylamine type
(10) Pentaerythritol bis-p-hydroxybenzaldehyde-p-toluidine type
3. The method according to claim 1, wherein the solvent is selected from one or more of ethanol, methanol, isopropanol, butanol, tetrahydrofuran, dioxane, toluene, dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone.
4. The method of claim 1,
in the step 2, the reaction is carried out for 10-60 min at-10 ℃, and then the reaction is carried out for 1-15 h at 80-120 ℃.
5. A decomposition method of a benzoxazine resin cured product containing a spiro acetal structure prepared according to the method of any one of claims 1 to 4, wherein the benzoxazine resin cured product is soaked in an acidic solution for 2-72 h,
the acid solution comprises an acid compound which is an organic acid or an inorganic acid,
the organic acid is selected from formic acid, acetic acid, p-toluenesulfonic acid, trifluoromethanesulfonic acid or trichloroacetic acid;
the inorganic acid is selected from hydrochloric acid, sulfuric acid, nitric acid or phosphoric acid.
6. The method according to claim 5, wherein the benzoxazine resin cured product is soaked in an acidic solution for 8-48 h.
7. The method according to claim 5, wherein the acidic solution further comprises a polar solvent, wherein the polar solvent is one or more of water, alcohol compounds, ketone compounds, ether compounds or amide compounds,
the alcohol compound is a compound containing one or more hydroxyl groups,
the ketone compound is selected from one or two of butanone and cyclohexanone,
the ether compound is one or more selected from ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, tetrahydrofuran and 1, 4-dioxane,
the amide compound is selected from one or more of dimethylformamide, dimethyl sulfoxide, sulfolane, N-methyl pyrrolidone, morpholine and N-methyl morpholine.
8. The method according to claim 7, wherein the alcohol compound is one or more of ethanol, methanol, glycerol, diethylene glycol and furfuryl alcohol.
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| EP3888940B1 (en) * | 2020-04-01 | 2023-01-11 | The Goodyear Tire & Rubber Company | A rubber composition and a rubber product |
| CN113637132B (en) * | 2020-05-11 | 2023-10-13 | 中国石油化工股份有限公司 | Benzoxazine resin and preparation method and application thereof |
| CN113698418A (en) * | 2020-05-21 | 2021-11-26 | 北京化工大学 | Bisacetamide compound containing spiro structure, and preparation method and application thereof |
| EP4015237A1 (en) * | 2020-12-17 | 2022-06-22 | The Goodyear Tire & Rubber Company | Rubber composition offering high stiffness and low hysteresis, method of manufacturing and tire |
| CN115403724A (en) * | 2021-05-27 | 2022-11-29 | 中国石油化工股份有限公司 | Main chain type benzoxazine resin, preparation method thereof, and bisphthalonitrile-based composite material and composite cured resin containing same |
| CN115433333B (en) * | 2021-06-02 | 2023-12-15 | 北京化工大学 | Benzoxazine resin with erythritol acetal structure |
| CN115433334B (en) * | 2021-06-02 | 2023-12-15 | 北京化工大学 | Main chain type benzoxazine resin with bis (trimethylol) propane acetal structure |
| CN115490824A (en) * | 2021-06-17 | 2022-12-20 | 中国石油化工股份有限公司 | End-capped benzoxazine resin, bisphthalonitrile-based composite material containing end-capped benzoxazine resin and composite cured resin |
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| WO2009070172A1 (en) * | 2007-11-30 | 2009-06-04 | Henkel Ag & Co. Kgaa | Curable resins containing acetal, ketal, acetal ester, or ketal ester linkages |
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