CN113429627B - P-aminobenzoic acid-condensed p-hydroxyl Schiff base/DOPO flame retardant, preparation method thereof and modified epoxy resin - Google Patents
P-aminobenzoic acid-condensed p-hydroxyl Schiff base/DOPO flame retardant, preparation method thereof and modified epoxy resin Download PDFInfo
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- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K5/00—Use of organic ingredients
- C08K5/49—Phosphorus-containing compounds
- C08K5/51—Phosphorus bound to oxygen
- C08K5/53—Phosphorus bound to oxygen bound to oxygen and to carbon only
- C08K5/5313—Phosphinic compounds, e.g. R2=P(:O)OR'
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- C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
- C07F9/00—Compounds containing elements of Groups 5 or 15 of the Periodic System
- C07F9/02—Phosphorus compounds
- C07F9/547—Heterocyclic compounds, e.g. containing phosphorus as a ring hetero atom
- C07F9/6564—Heterocyclic compounds, e.g. containing phosphorus as a ring hetero atom having phosphorus atoms, with or without nitrogen, oxygen, sulfur, selenium or tellurium atoms, as ring hetero atoms
- C07F9/6571—Heterocyclic compounds, e.g. containing phosphorus as a ring hetero atom having phosphorus atoms, with or without nitrogen, oxygen, sulfur, selenium or tellurium atoms, as ring hetero atoms having phosphorus and oxygen atoms as the only ring hetero atoms
- C07F9/657163—Heterocyclic compounds, e.g. containing phosphorus as a ring hetero atom having phosphorus atoms, with or without nitrogen, oxygen, sulfur, selenium or tellurium atoms, as ring hetero atoms having phosphorus and oxygen atoms as the only ring hetero atoms the ring phosphorus atom being bound to at least one carbon atom
- C07F9/657172—Heterocyclic compounds, e.g. containing phosphorus as a ring hetero atom having phosphorus atoms, with or without nitrogen, oxygen, sulfur, selenium or tellurium atoms, as ring hetero atoms having phosphorus and oxygen atoms as the only ring hetero atoms the ring phosphorus atom being bound to at least one carbon atom the ring phosphorus atom and one oxygen atom being part of a (thio)phosphinic acid ester: (X = O, S)
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- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K5/00—Use of organic ingredients
- C08K5/16—Nitrogen-containing compounds
- C08K5/17—Amines; Quaternary ammonium compounds
- C08K5/18—Amines; Quaternary ammonium compounds with aromatically bound amino groups
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- C08L2201/00—Properties
- C08L2201/02—Flame or fire retardant/resistant
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- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L2201/00—Properties
- C08L2201/22—Halogen free composition
Abstract
The para aminobenzoic acid condensed p-hydroxy Schiff base/DOPO flame retardant has a brand new molecular structure, does not contain halogen elements, is a green halogen-free environment-friendly flame retardant, does not pollute the environment during thermal cracking or combustion, is favorable for environment protection and sustainable development, and can ensure good flame retardant effect under the condition of low addition amount of the flame retardant through carrying out flame retardant and heat resistance tests on an epoxy resin composite material added with the flame retardant. In addition, the preparation method of the p-aminobenzoic acid condensed p-hydroxy Schiff base/DOPO flame retardant has the advantages of simple process, lower reaction temperature, higher safety, lower requirement on equipment and easiness for industrial large-scale production and application.
Description
Technical Field
The invention relates to the technical field of flame retardant materials, in particular to a p-aminobenzoic acid condensed p-hydroxyl Schiff base/DOPO flame retardant, a preparation method thereof and modified epoxy resin.
Background
The polymer materials have excellent properties and are widely applied to a plurality of fields at present, but many polymer materials, such as epoxy resin, have high flammability, are easily decomposed and combusted at high temperature, and have great harmfulness, so that flame retardants are often required to be added to the polymer materials to endow the polymer materials with flame retardancy.
Chinese patent 110156840A discloses a phosphorus-nitrogen type flame retardant containing DOPO. The compound is obtained by firstly forming R1 and R2 by one or two of H, C1-C18 alkyl, C6-C18 aryl, C3-C18 heteroaryl, fused cycloalkylaryl, fused cycloalkylheteroaryl, fused heterocyclylaaryl, fused heterocyclylheteroaryl and C1-C18 alkyl substituted by boron, silicon, oxygen, sulfur, carbonyl or sulfonyl, and then connecting R1 and R2 through saturated/unsaturated alkyl or forming heteroaryl, fused cycloalkylaryl, fused cycloalkylheteroaryl, fused heterocyclylaaryl or fused heterocyclylheteroaryl by N atoms. However, the flame retardant material can reach V0 grade when the addition amount of the flame retardant is at least 10wt%, for some nylon materials, the addition amount of the flame retardant even needs to reach 15 wt%, so that the addition amount of the flame retardant is large, the use cost is increased, the flame retardant effect is still to be improved after being reflected from the side surface, and in addition, the mechanical property of the polymer composite material is possibly influenced to a certain extent even if the addition amount of the flame retardant is too high.
Disclosure of Invention
One of the purposes of the invention is to provide a p-aminobenzoic acid condensed p-hydroxy Schiff base/DOPO flame retardant which can still obtain better flame retardant effect when the additive amount is lower.
In order to solve the technical problems, the invention adopts the following technical scheme: a p-aminobenzoic acid condensed p-hydroxyl Schiff base/DOPO flame retardant has a structural formula as follows:
in another aspect, the invention also relates to a preparation method of the p-aminobenzoic acid condensed p-hydroxy Schiff base/DOPO flame retardant, which comprises the following steps:
1. p-aminobenzoic acid condensed p-hydroxyl schiff base is prepared according to the following route:
2. the p-aminobenzoic acid condensed p-hydroxyl Schiff base/DOPO flame retardant is prepared according to the following route:
specifically, in the first step, a proper amount of p-aminobenzoic acid is dissolved in an organic solvent, a proper amount of p-hydroxybenzaldehyde is added after stirring and dissolving, the mixture is condensed and refluxed at 45-85 ℃, after the reaction is carried out for 2-6.0 h, an absolute ethyl alcohol solution of an alkaline substance (for example, a saturated absolute ethyl alcohol solution containing the alkaline substance) is dropwise added into a flask, an orange yellow solid is separated out after the pH value is controlled to be 5.0-8.0, the reaction is continued for 2.0h, and the p-aminobenzoic acid shrinkage p-hydroxyschiff base in an orange yellow powder solid state is obtained after suction filtration, washing, drying and grinding.
Wherein, the alkaline substance in the absolute ethyl alcohol solution with proper amount of alkaline substance is one or more of KOH, naOH, triethylamine and ethylenediamine.
Further, in the second step, a proper amount of p-aminobenzoic acid p-hydroxy Schiff base is taken to be dissolved in an organic solvent to obtain a dark brown solution, DOPO is added, the solution is condensed and refluxed at 50-80 ℃, the solution is gradually changed into a colorless solution from an initial orange yellow clear liquid, a white solid is generated along with the reaction, the reaction is stopped for 2.0 to 5.0 hours, and the white solid p-aminobenzoic acid p-hydroxy Schiff base/DOPO flame retardant is obtained through suction filtration, washing and drying.
Wherein the ratio of the amounts of the p-aminobenzoic acid condensed p-hydroxy Schiff base and DOPO is 1: (2 to 4).
Wherein, in the first step or the second step, the organic solvent is one or two of THF, MDF, acetonitrile, DMSO, methanol and ethanol.
Finally, the invention also relates to a modified epoxy resin, wherein the para aminobenzoic acid condensed para-hydroxyl Schiff base/DOPO flame retardant is added.
Further, the modified epoxy resin is prepared by the following steps: heating and melting 4, 4-diaminodiphenylmethane, cooling 4, 4-diaminodiphenylmethane to about 100 ℃, mixing the 4, 4-diaminodiphenylmethane with curing agent and p-aminobenzoic acid-condensed p-hydroxy Schiff base/DOPO flame retardant, uniformly stirring, adding epoxy resin under the condition of water bath, mixing and uniformly stirring, and curing to obtain the modified epoxy resin.
Wherein, in the step of preparing the modified epoxy resin, the curing operation comprises the following steps: curing at room temperature for 20h, curing at 100 ℃ for 3h, then placing in a vacuum drying oven at 160 ℃ for curing for 1h, and then naturally cooling to room temperature.
Wherein, in the step of preparing the modified epoxy resin, the mass content of the para aminobenzoic acid condensed para-hydroxyl Schiff base/DOPO flame retardant in the prepared modified epoxy resin is 1-7%.
The invention has the beneficial effects that: the p-aminobenzoic acid condensed p-hydroxy Schiff base/DOPO flame retardant provided by the invention can have good flame retardant effect only by adding a lower dosage to the epoxy resin composite material, so that the use cost of the flame retardant is reduced, and the risk that the mechanical property of the polymer composite material is influenced is reduced; moreover, the flame retardant has a brand new molecular structure, does not contain halogen elements, is a green halogen-free environment-friendly flame retardant, and does not cause pollution to the environment during thermal cracking or combustion; in addition, the preparation method of the p-aminobenzoic acid condensed p-hydroxy Schiff base/DOPO flame retardant provided by the invention has the advantages of simple process, low reaction temperature, low requirement on equipment, easiness for industrial large-scale production and application and high safety in the production process.
Drawings
FIG. 1 is an infrared spectrum of p-aminobenzoic acid condensed p-hydroxy Schiff base prepared in the example of the present invention.
FIG. 2 is a hydrogen spectrum of p-aminobenzoic acid condensed p-hydroxy Schiff base/DOPO flame retardant in the example of the present invention.
Detailed Description
For the understanding of those skilled in the art, the present invention will be further described with reference to the following examples and drawings, which are not intended to limit the present invention. It should be noted that the following examples are carried out in the laboratory, and it should be understood by those skilled in the art that the amounts of the components given in the examples are merely representative of the proportioning relationship between the components, and are not specifically limited.
1. Preparation of p-aminobenzoic acid condensed p-hydroxy Schiff base/DOPO flame retardant.
1. Preparation of p-aminobenzoic acid condensed p-hydroxyl Schiff base.
The preparation route of p-aminobenzoic acid condensed p-hydroxyl Schiff base is as follows:
the specific operation process is as follows: weighing 0.1-0.3 mol of p-aminobenzoic acid, dissolving the p-aminobenzoic acid in 50ml of organic solvent, stirring and dissolving, then adding 0.1-0.4 mol of p-hydroxybenzaldehyde into a three-neck flask, condensing and refluxing at 45-85 ℃, reacting for 2-6.0 h, then dropwise adding (ethylenediamine) absolute ethyl alcohol solution (for example, saturated absolute ethyl alcohol solution containing alkaline substances) of alkaline substances into the flask, and controlling the pH value: 5.0 to 8.0, orange yellow solid is separated out instantly, the reaction lasts for 2 hours, then the extraction is carried out, the reaction product is washed for three times by using absolute ethyl alcohol and is put in a vacuum drying oven at the temperature of 40 ℃ for 3 to 5.0 hours, and the dried solid is ground to finally obtain orange yellow powder solid, namely p-aminobenzoic acid condensed p-hydroxy Schiff base.
FIG. 1 is an infrared spectrum of p-aminobenzoic acid condensed p-hydroxyschiff base, from which it can be seen that the absorption peak of-CHO on aldehyde and the absorption peak of N-H of p-aminobenzoic acid disappear in the absorption spectrum of the compound, indicating that the condensation reaction of the raw materials occurs. And the compound has a strong C = N stretching vibration band at 1606.12 cm-1, and the peak is observed to be sharp and narrow, thereby indicating that the Schiff base is generated. P-aminobenzoic acid is therefore chosen as the starting material for providing N-H to react with organic aldehydes to prepare schiff bases.
2. Preparation of p-aminobenzoic acid condensed p-hydroxy Schiff base/DOPO flame retardant.
The preparation route of the p-aminobenzoic acid condensed p-hydroxyl Schiff base/DOPO flame retardant is as follows:
the specific operation process is as follows: weighing 0.02-0.06 mol of p-aminobenzoic acid p-hydroxy Schiff base, placing the p-aminobenzoic acid p-hydroxy Schiff base into a 150ml three-necked flask, adding 50-90 ml of organic solvent (one or two of THF, MDF, acetonitrile, DMSO, methanol and ethanol), stirring and dissolving completely, enabling the solution to be dark brown, adding 0.02-0.05 mol of DOPO into the flask, condensing and refluxing at 50-80 ℃, gradually changing the solution from initial orange yellow clear liquid into colorless solution along with the reaction, quickly generating white solid along with the reaction, stopping the reaction for 2.0-5.0 h, performing suction filtration, washing three times by using organic solvent, and drying in a vacuum drying oven at 30-60 ℃ for 3.0-5.0 h to finally obtain a white solid target product.
Fig. 2 is a hydrogen spectrum of the target product, and the target product is p-aminobenzoic acid-condensed p-hydroxy schiff base/DOPO flame retardant.
In order to facilitate the performance tests of the subsequent examples, three flame retardants, P1, P2 and P3, were provided, the preparation process of which was different:
p1 flame retardant: weighing 0.02mol of p-aminobenzoic acid p-hydroxy Schiff base, placing the p-aminobenzoic acid p-hydroxy Schiff base into a 150ml three-neck flask, adding 50ml of organic solvent (one or two of THF, MDF, acetonitrile, DMSO, methanol and ethanol), stirring and dissolving completely, enabling the solution to be dark brown, adding 0.02mol of DOPO into the flask, condensing and refluxing at 50 ℃, gradually changing the solution from initial orange yellow clear liquid into colorless solution along with the reaction, quickly generating white solid along with the reaction, stopping the reaction for 2.0h, performing suction filtration, washing with the organic solvent for three times, and drying in a vacuum drying oven at 30 ℃ for 3.0 h to finally obtain the target product of the white solid.
P2 flame retardant: weighing 0.06mol of p-aminobenzoic acid p-hydroxy Schiff base, placing the p-aminobenzoic acid p-hydroxy Schiff base into a 150ml three-neck flask, adding 90ml of organic solvent (one or two of THF, MDF, acetonitrile, DMSO, methanol and ethanol), stirring and dissolving completely, enabling the solution to be dark brown, adding 0.05 mol of DOPO into the flask, condensing and refluxing at 80 ℃, gradually changing the solution from initial orange yellow clear liquid into colorless solution along with the reaction, quickly generating white solid along with the reaction, stopping the reaction for 5.0h, performing suction filtration, washing with the organic solvent for three times, and drying in a vacuum drying oven at 60 ℃ for 5.0h to finally obtain the target product of the white solid.
P3 flame retardant: weighing 0.04mol of p-aminobenzoic acid p-hydroxy Schiff base, placing the p-aminobenzoic acid p-hydroxy Schiff base into a 150ml three-neck flask, adding 70ml of organic solvent (one or two of THF, MDF, acetonitrile, DMSO, methanol and ethanol), stirring and dissolving completely, enabling the solution to be dark brown, adding 0.03 mol of DOPO into the flask, condensing and refluxing at 65 ℃, gradually changing the solution from initial orange yellow clear liquid into colorless solution along with the reaction, quickly generating white solid along with the reaction, stopping the reaction for 3.5 h, performing suction filtration, washing with the organic solvent for three times, and drying in a vacuum drying oven at 45 ℃ for 4.0 h to finally obtain the target product of the white solid.
2. Preparing the p-aminobenzoic acid condensed p-hydroxyl Schiff base/DOPO flame-retardant composite material.
Example 1
Weighing 25.0 g of 4, 4-diaminodiphenylmethane in a 100mL beaker, heating and melting, cooling to about 100 ℃, adding 1% by mass of flame retardant P1 and a proper amount of curing agent, stirring and mixing uniformly, pouring 100g of epoxy resin which is weighed in advance and warmed in a 75 ℃ water bath into the beaker containing the curing agent and the flame retardant, quickly casting into a 130 x 6.5 x 3 national standard oxygen index sample bar and a 120 x 13 x 3.2 national standard vertical combustion sample bar mold after stirring uniformly, curing at room temperature for 20 hours, then curing at 100 ℃ for 3 hours, then placing in a 160 ℃ vacuum drying oven for curing for 1 hour, naturally cooling to room temperature and then demolding to obtain the target product.
Examples 2 to 8
Examples 2 to 8 are different from example 1 mainly in the selection of the flame retardant and the addition amount of the flame retardant in the composite material, the mass content of the flame retardant P1 in the whole composite material in example 2 is 3%, the mass content of the flame retardant P1 in the whole composite material in example 3 is 5%, and the mass content of the flame retardant P1 in the whole composite material in example 4 is 7%; the mass content of the flame retardant P2 in the whole composite material in the example 5 is 5 percent; the mass content of the flame retardant P2 in the whole composite material in the example 6 is 7 percent; the mass content of the flame retardant P3 in the whole composite material in example 7 is 5%; the content of the flame retardant P3 in the entire composite material in example 8 was 7% by mass.
3. And (3) testing the performance of the aminobenzoic acid condensed p-hydroxy Schiff base/DOPO flame-retardant composite material.
1. And (3) testing the flame retardant performance of the aminobenzoic acid condensed p-hydroxy Schiff base/DOPO flame retardant composite material.
The aminobenzoic acid reduced-p-hydroxy schiff base/DOPO flame-retardant composite material and the epoxy resin without the flame retardant (blank EP, as a control sample) were prepared into international oxygen index (o) sample bars with specification of 130 x 6.5 x 3 and international vertical combustion sample bars with specification of 125 x 13 x 3. The limit oxygen index is measured by a JF 3-oxygen index instrument, a UL-94 vertical combustion performance test is carried out by an FZ-5401 type vertical combustor, the limit oxygen index is measured by referring to a national standard method GB/T2406.2-2009, a GB/T2408-2008 standard is adopted for the UL-94 vertical combustion test, and the test results are shown in the following table:
TABLE 1
Wherein the weight percentages refer to the additive in relation to the total weight percentage of (epoxy resin EP-51 + curing agent).
The blank EP had an LOI value of 20.8 and a non-extinguishing time at combustion of 30s. As can be seen from the test results of the above table for examples 1-8, the oxygen index of the epoxy resin sample strip can be improved with the increase of the addition amount of the flame retardant within a certain range, and no obvious flame retardant effect is achieved when the addition amount is 1%; when the addition amount is increased to 3%, the oxygen index of the epoxy resin sample strip is greatly increased from 20.8% of a blank sample to 32.5%, an obvious flame retardant effect can be seen, the LOI value reaches the level of difficult combustion, the combustion time of the sample strip in a vertical combustion test is within 10s, and the V-0 level is reached, which indicates that the flame retardant has strong flame retardant capability; when the addition amount is increased to 5%, the LOI value of the epoxy resin sample strip reaches 33.2%, the UL-94 grade is still V-0, and the flame retardant effect is slightly improved compared with that of 3%, so that the flame retardant effect of the epoxy resin is better and better along with the increase of the addition amount of the flame retardant; however, when the amount of the flame retardant is increased to 7%, the LOI value of the epoxy resin is suddenly reduced to 29.3%, and the UL-94 rating is also reduced to V-1 rating, which indicates that the epoxy resin with the amount of 7% still has a certain flame retardant effect, but the flame retardant effect is much worse than that of the epoxy resin with the amount of 3% and 5%, and the reason for analyzing the LOI value is that the epoxy resin with the amount of 7% is larger, so that the epoxy resin is easy to agglomerate in an epoxy resin sample bar and is difficult to be uniformly distributed in the epoxy resin, and therefore, the flame retardant performance of the epoxy resin with the amount of 7% is rather inferior to that of the epoxy resin with the amount of 3% and 5%. Therefore, 5% of the amount of the flame retardant is required to be added into the epoxy resin, and a good flame retardant effect can be obtained with a small amount of the flame retardant.
2. And (3) testing the thermal performance of the aminobenzoic acid condensed p-hydroxy Schiff base/DOPO flame-retardant composite material.
Thermogravimetric analysis tests were performed on epoxy resin samples containing 5% and 7% of the P3 flame retardant, and the test results are shown in the following table:
TABLE 2 thermogravimetric analysis data of samples with different flame retardant contents
As can be seen from Table 2, the initial decomposition temperature of the flame-retardant epoxy resin sample at 5% level was about 258 deg.C, the initial decomposition temperature of the flame-retardant epoxy resin sample at 7% level was about 289 deg.C, but the char yield of the flame-retardant epoxy resin sample at 5% level was higher than that of the flame-retardant epoxy resin sample at 7% level. By combining the combustion test results of the flame-retardant epoxy resin sample, the flame retardant with the dosage of 5% is relatively suitable to be added into the epoxy resin, and the flame-retardant epoxy resin sample has good flame-retardant effect and thermal property.
In summary, the p-aminobenzoic acid condensed p-hydroxy Schiff base/DOPO flame retardant in the embodiment has a brand new molecular structure, does not contain halogen elements, is a green halogen-free environment-friendly flame retardant, and can ensure a good flame retardant effect under the condition that the additive amount of the flame retardant is lower (5%) after the epoxy resin is modified by using the flame retardant. In addition, the invention provides the preparation method of the flame retardant, which has the advantages of simple process, lower reaction temperature, higher safety, lower requirement on equipment and easier industrial large-scale production and application.
The above embodiments are preferred implementations of the present invention, and the present invention can be implemented in other ways without departing from the spirit of the present invention.
Some descriptions of the present invention have been simplified to facilitate understanding of the improvement of the present invention over the prior art by those of ordinary skill in the art, and some other elements have been omitted from this document for clarity, and those omitted elements should be recognized by those of ordinary skill in the art to constitute the content of the present invention.
Claims (7)
1. The p-aminobenzoic acid condensed p-hydroxyl Schiff base/DOPO flame retardant is characterized in that the structural formula is as follows:
the method for preparing the p-aminobenzoic acid condensed p-hydroxyl Schiff base/DOPO flame retardant comprises the following steps:
1. p-aminobenzoic acid condensed p-hydroxyl schiff base is prepared according to the following route:
2. p-aminobenzoic acid condensed p-hydroxyl Schiff base/DOPO flame retardant is prepared according to the following route:
in the first step: dissolving a proper amount of p-aminobenzoic acid in an organic solvent, stirring and dissolving, adding a proper amount of p-hydroxybenzaldehyde, condensing and refluxing at 45-85 ℃, reacting for 2-6.0 h, dropwise adding an absolute ethanol solution of an alkaline substance into a flask, controlling the pH value to be 5.0-8.0 to separate out an orange solid, continuously reacting for 2.0h, and performing suction filtration, washing, drying and grinding to obtain the orange powdery solid p-aminobenzoic acid p-hydroxy Schiff base;
in the second step: dissolving a proper amount of p-aminobenzoic acid condensed p-hydroxy Schiff base in an organic solvent to obtain a dark brown solution, adding DOPO, condensing and refluxing at 50-80 ℃, gradually changing the solution from an initial orange clear liquid to a colorless solution, generating a white solid along with the reaction, stopping the reaction for 2.0-5.0 h, and performing suction filtration, washing and drying to obtain the white solid p-aminobenzoic acid condensed p-hydroxy Schiff base/DOPO flame retardant.
2. The para-aminobenzoic acid para-hydroxy schiff base/DOPO flame retardant of claim 1, wherein: the alkaline substance in the absolute ethyl alcohol solution of the alkaline substance is one or more of KOH, naOH, triethylamine and ethylenediamine.
3. The para-aminobenzoic acid para-hydroxy schiff base/DOPO flame retardant of claim 1, wherein: the ratio of the p-aminobenzoic acid to the hydroxyl Schiff base to the DOPO is 1: (2 to 4).
4. The para-aminobenzoic acid para-hydroxy schiff base/DOPO flame retardant of claim 1, wherein: the organic solvent is one or two of THF, MDF, acetonitrile, DMSO, methanol and ethanol.
5. The modified epoxy resin is characterized in that: wherein the para-aminobenzoic acid para-hydroxy schiff base/DOPO flame retardant of claim 1 is added.
6. The modified epoxy resin according to claim 5, which is prepared by the following steps: heating and melting 4, 4-diaminodiphenylmethane, cooling 4, 4-diaminodiphenylmethane to 100 ℃, mixing the 4, 4-diaminodiphenylmethane with curing agent and p-aminobenzoic acid-condensed p-hydroxy Schiff base/DOPO flame retardant, stirring uniformly, adding epoxy resin under the condition of water bath, mixing and stirring uniformly, and curing to obtain the modified epoxy resin.
7. The modified epoxy resin according to claim 6, wherein: the mass content of the para aminobenzoic acid condensed para-hydroxyl Schiff base/DOPO flame retardant in the prepared modified epoxy resin is 1-7%.
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Application publication date: 20210924 Assignee: HENGYANG YILE NEW MATERIAL Co.,Ltd. Assignor: Hengyang Normal University Contract record no.: X2023980035966 Denomination of invention: P-Aminobenzoic acid p-hydroxy Schiff base/DOPO flame retardant and its preparation method and modified epoxy resin Granted publication date: 20230228 License type: Common License Record date: 20230529 |