CN109575076B - Preparation of phosphorus-containing bismaleimide and application of phosphorus-containing bismaleimide in flame-retardant epoxy resin - Google Patents
Preparation of phosphorus-containing bismaleimide and application of phosphorus-containing bismaleimide in flame-retardant epoxy resin Download PDFInfo
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- CN109575076B CN109575076B CN201811326637.4A CN201811326637A CN109575076B CN 109575076 B CN109575076 B CN 109575076B CN 201811326637 A CN201811326637 A CN 201811326637A CN 109575076 B CN109575076 B CN 109575076B
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- C—CHEMISTRY; METALLURGY
- 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
- C08K5/52—Phosphorus bound to oxygen only
- C08K5/521—Esters of phosphoric acids, e.g. of H3PO4
- C08K5/523—Esters of phosphoric acids, e.g. of H3PO4 with hydroxyaryl compounds
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- C—CHEMISTRY; METALLURGY
- 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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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L2201/00—Properties
- C08L2201/02—Flame or fire retardant/resistant
Abstract
The invention belongs to the field of flame retardants for epoxy resins, and particularly relates to a preparation method of phosphorus-containing bismaleimide and an application of the phosphorus-containing bismaleimide in flame-retardant epoxy resins. The preparation method comprises the following steps: dissolving a reactant N- (4-hydroxyphenyl) maleimide in tetrahydrofuran in a container provided with a nitrogen protection device under ice bath, adding triethylamine after the reactant N- (4-hydroxyphenyl) maleimide is completely dissolved, uniformly dispersing, and slowly dropwise adding a mixed solution of phenyl dichlorophosphate and tetrahydrofuran; stirring at room temperature after the dropwise addition is finished, reacting for 8-12h, performing suction filtration and rotary evaporation, washing the obtained light yellow viscous solid with ethyl acetate, ethanol and deionized water in sequence, purifying and drying, and refining with a mixed solvent of ethyl acetate and petroleum ether to obtain the target product, namely the phosphorus-containing bismaleimide. The phosphorus-containing bismaleimide prepared by the invention can form an interpenetrating polymer network structure with epoxy resin under the action of an amine curing agent, has an obvious flame-retardant effect, and can achieve the purposes of low addition and high-efficiency flame retardance.
Description
Technical Field
The invention belongs to the field of flame retardants for epoxy resins, and particularly relates to a preparation method of phosphorus-containing bismaleimide and an application of the phosphorus-containing bismaleimide in flame-retardant epoxy resins.
Background
Epoxy resins (EP) have high tensile strength and modulus, good chemical and corrosion resistance, excellent dimensional stability and electrical properties, and are widely used in many fields such as manufacturing, electronics and electrical, and aerospace. However, the flammability of epoxy resins greatly limits their use and leaves fire safety hazards in use. Therefore, the design and development of a high-efficiency flame-retardant epoxy resin system become an urgent problem to be solved in the field. Among them, phosphorus flame retardants are widely studied in flame-retardant epoxy resins because of their outstanding flame-retardant effects, low environmental pollution, and the like.
However, the phosphorus flame retardants widely used for flame retarding epoxy resins have the problems of low thermal stability, easy hydrolysis and the like, and the addition amount of the flame retardants is large. And the mechanical property of the epoxy resin is reduced to some extent due to excessively high addition amount, which is not beneficial to processing and application.
CN 103588990A discloses a series of heat-resistant reactive maleimide structure phosphorus-containing flame retardants and a preparation method thereof, which can achieve a certain flame-retardant effect in unsaturated resins. However, the relevant flame retardant synthesis process needs to be heated to 70-100 ℃, and corrosive gas hydrogen halide is released in the reaction process.
The invention provides a synthesis method of novel phosphorus-containing bismaleimide and application of flame-retardant epoxy resin thereof, the compound has maleimide groups which can be crosslinked with epoxy resin to form an interpenetrating polymer network structure under the action of an amine curing agent, and particularly compared with the prior art, the compound has the advantages of simple preparation process, mildness and low energy consumption, has the advantages of low addition and high-efficiency flame-retardant epoxy resin, can ensure that the epoxy resin passes through vertical combustion V-0 grade by controlling the addition amount to be below 4 percent, has the limit oxygen index to be above 30 percent, and solves the problem of difficult balance among flame retardant property, mechanical property and heat resistance of the epoxy resin.
Disclosure of Invention
The invention provides a preparation method of phosphorus-containing bismaleimide and an application of the phosphorus-containing bismaleimide in flame-retardant epoxy resin, aiming at solving the problem that the flame-retardant property, the mechanical property and the heat resistance of the epoxy resin are difficult to balance.
The invention is realized by the following technical scheme: a preparation method of phosphorus-containing bismaleimide, wherein the structural formula of the phosphorus-containing bismaleimide is as follows:
the preparation method comprises the following steps: dissolving a reactant N- (4-hydroxyphenyl) maleimide in tetrahydrofuran in a container provided with a nitrogen protection device under ice bath, adding triethylamine after all reactants are dissolved, uniformly dispersing, and slowly dropwise adding a mixed solution of phenyl dichlorophosphate and tetrahydrofuran (the temperature of the raw material in the container under ice bath is 5-7 ℃); stirring at room temperature after the dropwise addition is finished, reacting for 8-12h, performing suction filtration and rotary evaporation, washing the obtained light yellow viscous solid with ethyl acetate, ethanol and deionized water in sequence, purifying and drying, and refining with a mixed solvent of ethyl acetate and petroleum ether to obtain the target product, namely the phosphorus-containing bismaleimide.
As a further improvement of the technical scheme of the invention, the molar ratio of the N- (4-hydroxyphenyl) maleimide to the triethylamine is 1: 1.2-1.3.
The invention further provides application of the phosphorus-containing bismaleimide prepared by the preparation method of the phosphorus-containing bismaleimide as a flame retardant in flame-retardant epoxy resin. The specific implementation method for flame-retardant modification of the epoxy resin comprises the following steps: through stirring and ultrasound, firstly, phosphorus-containing bismaleimide and epoxy resin are dispersed in a proper amount of acetone solvent, after the phosphorus-containing bismaleimide and the epoxy resin are uniformly dispersed, the mixture is heated at the temperature of 60 ℃, and simultaneously, the solvent is removed through vacuum degassing. Mixing 4, 4-diaminodiphenylmethane heated and melted at 92-100 ℃, mechanically stirring for 1-3min, placing in a vacuum oven, degassing, and casting in a stainless steel mold.
As a further improvement of the application technical scheme of the invention, the addition amount of the phosphorus-containing maleimide is 1 wt% -4 wt%.
As a further improvement of the technical scheme of the application of the invention, the addition amount of the phosphorus-containing maleimide is preferably 2 wt%.
The invention further provides application of the compound flame retardant consisting of the phosphorus-containing bismaleimide (PDMP) prepared by the preparation method of the phosphorus-containing bismaleimide and 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) in flame-retardant epoxy resin. Dissolving appropriate amount of bismaleimide flame retardant PDMP, DOPO and epoxy resin in appropriate amount of tetrahydrofuran solvent simultaneously by ultrasonic dispersion method, heating at 45 deg.C, vacuum degassing to remove solvent, mixing with 4, 4-diaminodiphenylmethane heated and melted at 92-100 deg.C, mechanically stirring for 1-3min, placing in vacuum oven, degassing, and casting in stainless steel mold.
As a further improvement of another application technical scheme of the invention, the phosphorus-containing bismaleimide and 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide compound weight ratio in the compound flame retardant is 3: 1-9, and the addition amount of the compound flame retardant is 1-4 wt%.
Compared with the prior epoxy resin flame retardant and flame retardant method, the invention has the following advantages:
(1) the preparation process of the phosphorus-containing bismaleimide provided by the invention is simple, mild in reaction condition, energy-saving and environment-friendly, and suitable for industrial production.
(2) The phosphorus-containing bismaleimide prepared by the invention can form an interpenetrating polymer network structure with epoxy resin under the action of an amine curing agent, has a remarkable flame-retardant effect, can achieve the aim of low-addition high-efficiency flame retardance, and simultaneously keeps or improves the thermal property and the mechanical property of the epoxy resin.
(3) The invention provides a phosphorus-containing bismaleimide and 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) compound flame retardant system, which can further improve the flame retardant property of epoxy resin under low addition.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is an infrared spectrum of PDMP, a phosphorus-containing bismaleimide flame retardant of the present invention. As can be seen from the figure: 761.01cm in the PDCP spectrogram of the raw material-1Absorption peak of P-Cl bond at 3478.9cm in the 4-HPM spectrum of the raw material-1Of phenolic hydroxy groupsThe absorption peaks all disappeared in the product PDMP spectrum, while 1184, 1162, 1233, 1213cm in the PDMP spectrum-1And new absorption peaks of P ═ O and P-O-Ph bonds appear nearby, so that the completion of the substitution reaction of P-Cl and phenolic hydroxyl is proved, and the structure of the target product is determined.
FIG. 2 is a nuclear magnetic hydrogen spectrum of PDMP which is a flame retardant containing phosphorus bismaleimide. As can be seen from the figure: the single peak (Ha) appearing between 7.20ppm is attributed to 4 protons on the double bond in the maleimide group; the multiplet (Hd, Hf) occurring between 7.34 and 7.31ppm is ascribed to 3 protons in the meta-position of the benzene ring structure in phenyl dichlorophosphate; peaks (Hb, Hc) appearing between 7.46 and 7.44ppm are assigned to 8 protons on the benzene ring in N- (4-hydroxyphenyl) maleimide; the peak (He) appearing between 7.49 and 7.47ppm is ascribed to 2 protons at the para-position of the benzene ring in phenyl dichlorophosphate. The nuclear magnetic hydrogen spectrum data of the product proves that the structure of the target product is correct.
FIG. 3 is a nuclear magnetic phosphorus spectrum of PDMP, a phosphorus-containing bismaleimide flame retardant of the present invention. As can be seen from the figure: a pure single peak appears at-17.29 ppm in the product spectrum, which corresponds to only one chemical environment phosphorus element in the structure of the target product, and the purity of the product is proved.
The results of fig. 1-3 collectively demonstrate that the PDMP flame retardant is consistent with the target structure.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be described in detail below. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the examples given herein without any inventive step, are within the scope of the present invention.
The technical solution of the present invention will be described in detail below with reference to the accompanying drawings.
Example 1
The preparation method of the phosphorus-containing bismaleimide comprises the following steps:
(1) in a 250mL reaction vessel equipped with stirring, 7.65g N- (4-hydroxyphenyl) maleimide and 50mL tetrahydrofuran were added under ice-bath and dissolved by magnetic stirring; after complete dissolution, 5.3g of triethylamine was added and stirring was continued until uniform mixing occurred. Then, 4.5g of a mixed solution of phenyl dichlorophosphate and tetrahydrofuran was added dropwise to the reaction vessel at 5-7 ℃ to gradually form a white precipitate.
(2) After the solution is dropwise added, the system is reacted for 10 hours at room temperature, white precipitate triethylamine hydrochloride is filtered and then distilled under reduced pressure, and a light yellow solid product is obtained after purification and drying by utilizing ethyl acetate and petroleum ether, wherein the yield is 91.7%.
Example 2
The preparation method of the phosphorus-containing bismaleimide comprises the following steps:
(1) in a 250mL reaction vessel equipped with stirring, 7.65g N- (4-hydroxyphenyl) maleimide and 50mL tetrahydrofuran were added under ice-bath and dissolved by magnetic stirring; after complete dissolution, 4.89g of triethylamine was added and stirring was continued until uniform mixing occurred. Then, 4.5g of a mixed solution of phenyl dichlorophosphate and tetrahydrofuran was added dropwise to the reaction vessel at 5-7 ℃ to gradually form a white precipitate.
(2) After the solution is dropwise added, the system is reacted for 12 hours at room temperature, white precipitate triethylamine hydrochloride is filtered and then distilled under reduced pressure, and a light yellow solid product is obtained after purification and drying by utilizing ethyl acetate and petroleum ether, wherein the yield is 92.5%.
Comparative example 1
The preparation method of the phosphorus-containing bismaleimide comprises the following steps:
(1) in a 250mL reaction vessel equipped with stirring, 7.65g N- (4-hydroxyphenyl) maleimide and 50mL tetrahydrofuran were added at room temperature and dissolved by magnetic stirring; after complete dissolution, 5.30g of triethylamine was added and stirring was continued until uniform mixing occurred. Then, a mixed solution of 4.5g of phenyl dichlorophosphate and tetrahydrofuran was added dropwise to the above reaction vessel at room temperature, and a white precipitate was gradually formed in the system.
(2) After the solution is dropwise added, the system is continuously reacted for 10 hours at room temperature, white precipitate triethylamine hydrochloride is filtered and then is subjected to reduced pressure distillation, and a light yellow solid product is obtained after purification and drying by utilizing ethyl acetate and petroleum ether, wherein the yield is 83.0%.
Comparing example 2 with comparative example 1, it can be seen that: example 2 during step (1), the raw material mixing was performed under ice bath conditions (raw material mixing temperature condition of 5-7 ℃), while comparative example 1 was performed at room temperature, but steps (1) and (2) performed at room temperature resulted in a problem of yield reduction. This is because the step (1) carried out at room temperature causes a problem that the reaction rate is too fast, resulting in a decrease in yield. Therefore, the invention preferably adopts the technical scheme that in the step (1), the raw material mixing is carried out under ice bath conditions (5-7 ℃ condition).
Example 3
The preparation method of the phosphorus-containing bismaleimide comprises the following steps:
(1) in a 250mL reaction vessel equipped with stirring, 7.65g N- (4-hydroxyphenyl) maleimide and 50mL tetrahydrofuran were added under ice-bath and dissolved by magnetic stirring; after complete dissolution, 5.35g of triethylamine was added and stirring was continued until uniform mixing occurred. Then, 4.5g of a mixed solution of phenyl dichlorophosphate and tetrahydrofuran was added dropwise to the reaction vessel at 5-7 ℃ to gradually form a white precipitate.
(2) After the solution is dropwise added, the system is reacted for 8 hours at room temperature, white precipitate triethylamine hydrochloride is filtered and then distilled under reduced pressure, and a light yellow solid product is obtained after purification and drying by utilizing ethyl acetate and petroleum ether, wherein the yield is 95.3%.
Examples 4 to 20
The phosphorus-containing bismaleimide PDMP (or the phosphorus-containing bismaleimide PDMP and DOPO are compounded) prepared by the method is used for preparing the flame-retardant epoxy resin composite material. The phosphorus-containing bismaleimide PDMP (or the phosphorus-containing bismaleimide PDMP and DOPO are mixed according to a reasonable formula ratio), the mixture and epoxy resin are uniformly dispersed in an acetone or tetrahydrofuran solvent together through stirring and ultrasound, and then the solvent is removed by heating at 60 ℃ (or 45 ℃) in a vacuum oven. And 4, 4-diaminodiphenylmethane (DDM) heated and melted at the temperature of 92-100 ℃ is mixed with the epoxy resin, mechanically stirred for 1-3min, placed in a vacuum oven at the temperature of 60 ℃ for degassing, cast and cured after complete degassing, cured for 2h at the temperature of 100 ℃ and cured for 4h at the temperature of 150 ℃ to obtain the flame-retardant epoxy resin composite material. The UL-94 test results and LOI values of the flame retardants with different components and contents are tested and compared, and are shown in Table 1.
TABLE 1 comparison of formulation and Combustion behavior test results for various epoxy resin composites
As can be seen from the above table: when 1 wt%, 2 wt%, 3 wt% and 4 wt% of the PDMP flame retardant disclosed by the invention is independently added for flame-retarding epoxy resin, the flame-retardant grade and the Limiting Oxygen Index (LOI) value are superior to those of DOPO flame retardant with corresponding content; meanwhile, when the PDMP and the DOPO form a composite flame retardant system in a scientific proportion for flame retarding of epoxy resin, the flame retarding effect of the composite flame retardant with the same content is obviously better than that of the composite flame retardant with the PDMP or the DOPO added separately.
The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.
Claims (4)
1. A preparation method of phosphorus-containing bismaleimide, wherein the structural formula of the phosphorus-containing bismaleimide is as follows:
the preparation method is characterized by comprising the following steps: dissolving a reactant N- (4-hydroxyphenyl) maleimide in tetrahydrofuran in a container provided with a nitrogen protection device under ice bath, adding triethylamine after the reactant N- (4-hydroxyphenyl) maleimide is completely dissolved, uniformly dispersing, and slowly dropwise adding a mixed solution of phenyl dichlorophosphate and tetrahydrofuran; stirring at room temperature after the dropwise addition is finished, reacting for 8-12h, performing suction filtration and rotary evaporation, washing the obtained light yellow viscous solid with ethyl acetate, ethanol and deionized water in sequence, purifying and drying, and refining with a mixed solvent of ethyl acetate and petroleum ether to obtain the target product, namely the phosphorus-containing bismaleimide.
2. The process according to claim 1, wherein the molar ratio of N- (4-hydroxyphenyl) maleimide to triethylamine is 1:1.2 to 1.3.
3. The use of the complex flame retardant comprising the phosphorus-containing bismaleimide prepared by the method of claim 1 or 2 and 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide in flame retardant epoxy resins.
4. The application of claim 3, wherein the phosphorus-containing bismaleimide and 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide are compounded in the compound flame retardant in a weight ratio of 3: 1-9, and the addition amount of the compound flame retardant is 1-4 wt%.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103588990A (en) * | 2013-11-13 | 2014-02-19 | 中国科学技术大学 | Heat-resisting reaction type phosphorate containing flame retardant with maleimide structure and preparation method thereof |
| CN105086449A (en) * | 2015-09-11 | 2015-11-25 | 西北工业大学 | Phosphorus-containing POSS (polyhedral oligomeric silsesquioxane) flame-retardant bismaleimide resin and preparation method thereof |
| CN107868228A (en) * | 2016-09-28 | 2018-04-03 | 广东生益科技股份有限公司 | A kind of phosphorous imido organosilicon epoxy resin and its preparation method and application |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103588990A (en) * | 2013-11-13 | 2014-02-19 | 中国科学技术大学 | Heat-resisting reaction type phosphorate containing flame retardant with maleimide structure and preparation method thereof |
| CN105086449A (en) * | 2015-09-11 | 2015-11-25 | 西北工业大学 | Phosphorus-containing POSS (polyhedral oligomeric silsesquioxane) flame-retardant bismaleimide resin and preparation method thereof |
| CN107868228A (en) * | 2016-09-28 | 2018-04-03 | 广东生益科技股份有限公司 | A kind of phosphorous imido organosilicon epoxy resin and its preparation method and application |
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