CN114957619A - Epoxy flame-retardant composite material containing imidazole curing accelerator and preparation method thereof - Google Patents
Epoxy flame-retardant composite material containing imidazole curing accelerator and preparation method thereof Download PDFInfo
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- RAXXELZNTBOGNW-UHFFFAOYSA-N imidazole Natural products C1=CNC=N1 RAXXELZNTBOGNW-UHFFFAOYSA-N 0.000 title claims abstract description 150
- RNFJDJUURJAICM-UHFFFAOYSA-N 2,2,4,4,6,6-hexaphenoxy-1,3,5-triaza-2$l^{5},4$l^{5},6$l^{5}-triphosphacyclohexa-1,3,5-triene Chemical compound N=1P(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP=1(OC=1C=CC=CC=1)OC1=CC=CC=C1 RNFJDJUURJAICM-UHFFFAOYSA-N 0.000 title claims abstract description 52
- 239000003063 flame retardant Substances 0.000 title claims abstract description 52
- 239000002131 composite material Substances 0.000 title claims abstract description 40
- 239000004593 Epoxy Substances 0.000 title claims abstract description 29
- 238000002360 preparation method Methods 0.000 title abstract description 11
- 239000003822 epoxy resin Substances 0.000 claims abstract description 46
- 229920000647 polyepoxide Polymers 0.000 claims abstract description 46
- UBIJTWDKTYCPMQ-UHFFFAOYSA-N hexachlorophosphazene Chemical compound ClP1(Cl)=NP(Cl)(Cl)=NP(Cl)(Cl)=N1 UBIJTWDKTYCPMQ-UHFFFAOYSA-N 0.000 claims abstract description 24
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 12
- 125000002883 imidazolyl group Chemical group 0.000 claims abstract description 7
- 229910052739 hydrogen Inorganic materials 0.000 claims abstract description 6
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims abstract description 5
- 125000001309 chloro group Chemical group Cl* 0.000 claims abstract description 5
- 239000001257 hydrogen Substances 0.000 claims abstract description 5
- YMWUJEATGCHHMB-UHFFFAOYSA-N Dichloromethane Chemical compound ClCCl YMWUJEATGCHHMB-UHFFFAOYSA-N 0.000 claims description 20
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 claims description 18
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 14
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Chemical compound [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 claims description 10
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 claims description 9
- 238000000034 method Methods 0.000 claims description 8
- GKTNLYAAZKKMTQ-UHFFFAOYSA-N n-[bis(dimethylamino)phosphinimyl]-n-methylmethanamine Chemical compound CN(C)P(=N)(N(C)C)N(C)C GKTNLYAAZKKMTQ-UHFFFAOYSA-N 0.000 claims description 8
- 229910052757 nitrogen Inorganic materials 0.000 claims description 7
- 239000000047 product Substances 0.000 claims description 7
- 238000003756 stirring Methods 0.000 claims description 6
- 238000004821 distillation Methods 0.000 claims description 5
- 239000000203 mixture Substances 0.000 claims description 5
- 229910000027 potassium carbonate Inorganic materials 0.000 claims description 5
- MWSKJDNQKGCKPA-UHFFFAOYSA-N 6-methyl-3a,4,5,7a-tetrahydro-2-benzofuran-1,3-dione Chemical compound C1CC(C)=CC2C(=O)OC(=O)C12 MWSKJDNQKGCKPA-UHFFFAOYSA-N 0.000 claims description 4
- 238000006243 chemical reaction Methods 0.000 claims description 4
- 238000002156 mixing Methods 0.000 claims description 4
- 239000013078 crystal Substances 0.000 claims description 3
- 238000001035 drying Methods 0.000 claims description 3
- 239000000706 filtrate Substances 0.000 claims description 3
- 238000001914 filtration Methods 0.000 claims description 3
- 238000004519 manufacturing process Methods 0.000 claims description 3
- 239000002904 solvent Substances 0.000 claims description 3
- 238000005406 washing Methods 0.000 claims description 3
- KXGFMDJXCMQABM-UHFFFAOYSA-N 2-methoxy-6-methylphenol Chemical compound [CH]OC1=CC=CC([CH])=C1O KXGFMDJXCMQABM-UHFFFAOYSA-N 0.000 claims description 2
- VPWNQTHUCYMVMZ-UHFFFAOYSA-N 4,4'-sulfonyldiphenol Chemical compound C1=CC(O)=CC=C1S(=O)(=O)C1=CC=C(O)C=C1 VPWNQTHUCYMVMZ-UHFFFAOYSA-N 0.000 claims description 2
- LGRFSURHDFAFJT-UHFFFAOYSA-N Phthalic anhydride Natural products C1=CC=C2C(=O)OC(=O)C2=C1 LGRFSURHDFAFJT-UHFFFAOYSA-N 0.000 claims description 2
- 239000004841 bisphenol A epoxy resin Substances 0.000 claims description 2
- 239000004842 bisphenol F epoxy resin Substances 0.000 claims description 2
- JHIWVOJDXOSYLW-UHFFFAOYSA-N butyl 2,2-difluorocyclopropane-1-carboxylate Chemical compound CCCCOC(=O)C1CC1(F)F JHIWVOJDXOSYLW-UHFFFAOYSA-N 0.000 claims description 2
- 239000007810 chemical reaction solvent Substances 0.000 claims description 2
- 239000005007 epoxy-phenolic resin Substances 0.000 claims description 2
- 229920001568 phenolic resin Polymers 0.000 claims description 2
- SRPWOOOHEPICQU-UHFFFAOYSA-N trimellitic anhydride Chemical compound OC(=O)C1=CC=C2C(=O)OC(=O)C2=C1 SRPWOOOHEPICQU-UHFFFAOYSA-N 0.000 claims description 2
- 238000004100 electronic packaging Methods 0.000 abstract description 2
- 238000001938 differential scanning calorimetry curve Methods 0.000 description 8
- 238000007711 solidification Methods 0.000 description 7
- 230000008023 solidification Effects 0.000 description 7
- LNEPOXFFQSENCJ-UHFFFAOYSA-N haloperidol Chemical compound C1CC(O)(C=2C=CC(Cl)=CC=2)CCN1CCCC(=O)C1=CC=C(F)C=C1 LNEPOXFFQSENCJ-UHFFFAOYSA-N 0.000 description 5
- 229910052698 phosphorus Inorganic materials 0.000 description 5
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 4
- IISBACLAFKSPIT-UHFFFAOYSA-N bisphenol A Chemical compound C=1C=C(O)C=CC=1C(C)(C)C1=CC=C(O)C=C1 IISBACLAFKSPIT-UHFFFAOYSA-N 0.000 description 4
- 239000011574 phosphorus Substances 0.000 description 4
- 238000001228 spectrum Methods 0.000 description 4
- 239000000654 additive Substances 0.000 description 3
- 230000000996 additive effect Effects 0.000 description 3
- 238000011161 development Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 238000002485 combustion reaction Methods 0.000 description 2
- 238000002329 infrared spectrum Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 238000000655 nuclear magnetic resonance spectrum Methods 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 238000000197 pyrolysis Methods 0.000 description 2
- 230000009257 reactivity Effects 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- WKBOTKDWSSQWDR-UHFFFAOYSA-N Bromine atom Chemical compound [Br] WKBOTKDWSSQWDR-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical group [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 238000001157 Fourier transform infrared spectrum Methods 0.000 description 1
- UEZVMMHDMIWARA-UHFFFAOYSA-N Metaphosphoric acid Chemical compound OP(=O)=O UEZVMMHDMIWARA-UHFFFAOYSA-N 0.000 description 1
- YUWBVKYVJWNVLE-UHFFFAOYSA-N [N].[P] Chemical compound [N].[P] YUWBVKYVJWNVLE-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- GDTBXPJZTBHREO-UHFFFAOYSA-N bromine Substances BrBr GDTBXPJZTBHREO-UHFFFAOYSA-N 0.000 description 1
- 229910052794 bromium Inorganic materials 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 238000003763 carbonization Methods 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000005034 decoration Methods 0.000 description 1
- XPPKVPWEQAFLFU-UHFFFAOYSA-N diphosphoric acid Chemical compound OP(O)(=O)OP(O)(O)=O XPPKVPWEQAFLFU-UHFFFAOYSA-N 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 231100000956 nontoxicity Toxicity 0.000 description 1
- 230000000269 nucleophilic effect Effects 0.000 description 1
- 238000010534 nucleophilic substitution reaction Methods 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 125000004437 phosphorous atom Chemical group 0.000 description 1
- 229920001296 polysiloxane Polymers 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000000425 proton nuclear magnetic resonance spectrum Methods 0.000 description 1
- 229940005657 pyrophosphoric acid Drugs 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 229920001187 thermosetting polymer Polymers 0.000 description 1
- 239000002341 toxic gas Substances 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
- 239000002023 wood Substances 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
- C08G59/18—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing
- C08G59/68—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing characterised by the catalysts used
- C08G59/688—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing characterised by the catalysts used containing phosphorus
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- 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 Table
- 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
- C07F9/6581—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 nitrogen atoms with or without oxygen or sulfur atoms, as ring hetero atoms
- C07F9/65812—Cyclic phosphazenes [P=N-]n, n>=3
- C07F9/65815—Cyclic phosphazenes [P=N-]n, n>=3 n = 3
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- Molecular Biology (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Epoxy Resins (AREA)
Abstract
The invention discloses an epoxy flame-retardant composite material containing imidazole curing accelerator and a preparation method thereof, wherein the epoxy flame-retardant composite material is composed of epoxy resin, a curing agent and the imidazole curing accelerator, the imidazole curing accelerator is prepared by reacting hexachlorocyclotriphosphazene with imidazole and substituting six chlorine atoms on the hexachlorocyclotriphosphazene by active hydrogen on an imidazole ring. The imidazole curing accelerator can effectively improve the flame retardance of epoxy resin, prolongs the ignition time of composite materials, obviously reduces the heat release rate and the total heat release amount, and has wide application prospect in electronic packaging and building industries.
Description
Technical Field
The invention relates to an epoxy flame-retardant composite material containing imidazole curing accelerators and a preparation method thereof, belonging to the field of flame-retardant composite materials.
Background
Epoxy resin is an important thermosetting resin, has excellent comprehensive performance, has mature industrial preparation process, and is widely applied to various aspects of production and life, such as rust prevention of metal materials, addition of functionality or decoration to wood boards, high-performance adhesive and the like. However, the Limiting Oxygen Index (LOI) of the common epoxy resin is only about 20%, and the application of the epoxy resin is limited to a great extent due to the inflammability of the common epoxy resin. With the rapid development of high-precision industries, the flame retardancy of epoxy resins is gradually unable to meet the demand, so the development of highly effective flame retardant epoxy resins is imminent.
Flame-retardant epoxy resins are generally classified into additive type and reactive type. The additive type epoxy resin has simple process and wide raw material source, is a type which is frequently used in the world at present, but the addition of the additive also causes the problems of dispersibility, compatibility and interfacial property, and the mechanical property of the epoxy resin is greatly influenced. The reactive flame-retardant curing accelerator can directly introduce flame-retardant elements into an epoxy resin chain, and if the reactive flame-retardant curing accelerator is used as a curing agent, the epoxy resin has a long-term flame-retardant effect and has small influence on the mechanical property of an epoxy system. At present, bromine elements such as brominated epoxy resin and the like are mainly introduced into the epoxy resin, but the brominated epoxy resin generates a large amount of toxic gas during combustion, so that the brominated epoxy resin is harmful to human health and has very limited application, and people urgently need other types of flame-retardant epoxy resin. Therefore, the development of epoxy resins containing phosphorus and nitrogen and silicone epoxy resins has been regarded as important.
The cyclopolyphosphazene has the advantages of alternate arrangement of nitrogen and phosphorus, high nitrogen and phosphorus content, flame retardant capability endowed by chemical composition and structure, good biocompatibility and no toxicity and harm, and is an environment-friendly raw material. Therefore, Hexachlorocyclotriphosphazene (HCCP) has great flame retardant potential as the compound. The HCCP structure has active nucleophilic reactive groups, and various structures are introduced through nucleophilic substitution reaction. Imidazole has a hetero-ring structure with a high nitrogen content, and the structure of imidazole can effectively cure epoxy resin. Therefore, the imidazole curing accelerator is designed on the basis of the preparation method and is used for preparing the epoxy flame-retardant composite material.
Disclosure of Invention
The invention aims to provide an epoxy flame-retardant composite material containing an imidazole curing accelerator and a preparation method thereof, so as to improve the flame retardance of epoxy resin.
The invention adopts the following technical scheme for realizing the purpose:
an epoxy flame-retardant composite material containing imidazole curing accelerator is characterized in that: the epoxy flame-retardant composite material consists of epoxy resin, a curing agent and an imidazole curing accelerator;
the imidazole curing accelerator is hexa-imidazolyl phosphazene with a structural formula shown in a formula (1) obtained by reacting hexachlorocyclotriphosphazene with imidazole and substituting six chlorine atoms on the hexachlorocyclotriphosphazene with active hydrogen on an imidazole ring;
further, the epoxy resin is at least one of bisphenol A epoxy resin, bisphenol F epoxy resin, phenolic resin and bisphenol S type epoxy resin.
Further, the curing agent is at least one of methyltetrahydrophthalic anhydride, phthalic anhydride and trimellitic anhydride.
Further, the preparation method of the imidazole curing accelerator, hexaimidazolylphosphazene, comprises the following steps: imidazole and anhydrous potassium carbonate are added into a three-neck flask, tetrahydrofuran is added to serve as a reaction solvent, air is pumped out by a vacuum pump, and then nitrogen is introduced for protection; dissolving hexachlorocyclotriphosphazene in a proper amount of tetrahydrofuran, dripping the solution into an imidazole solution by using a dropping funnel, and stirring and reacting for 1-2 hours at the temperature of 30-35 ℃; and (3) after the reaction is finished, filtering to obtain filtrate, distilling at the temperature of 30-35 ℃ under reduced pressure to remove the solvent, washing with tetrahydrofuran, and finally drying the product in a vacuum oven at the temperature of 30-35 ℃ overnight to obtain white crystal hexaimidazolyl phosphazene (recorded as HIMPH).
Further, the mass ratio of imidazole to anhydrous potassium carbonate to hexachlorocyclotriphosphazene is (7-8): 2-3: 3.
the preparation method of the epoxy flame-retardant composite material comprises the following steps: dissolving hexaimidazolylphosphazene in a proper amount of dichloromethane, adding epoxy resin and a curing agent, mixing, mechanically stirring until the solution is clear and transparent, then carrying out reduced pressure distillation to remove dichloromethane, pouring the obtained mixture into a mold, carrying out vacuum defoaming, and curing to obtain the epoxy flame-retardant composite material containing the imidazole curing accelerator.
Further, the mass ratio of the epoxy resin to the curing agent is 6: 5-5.5, and the mass ratio of the hexaimidazolyl phosphorus to the epoxy resin is 1-11.5: 100.
Further, the temperature of the reduced pressure distillation is 80 ℃, the vacuum deaeration is carried out for 0.5h at 80 ℃, and the curing is carried out for 1h at 80 ℃ and then for 1h at 90 ℃.
Compared with the prior art, the invention has the beneficial effects that:
1. the imidazole curing accelerator can effectively improve the flame retardance of epoxy resin, prolongs the ignition time of composite materials, obviously reduces the heat release rate and the total heat release amount, and has wide application prospect in electronic packaging and building industries.
2. The epoxy flame-retardant composite material containing the imidazole curing accelerator is simple in preparation method and convenient to use, can be cured at a lower temperature, and can be applied to actual production and life.
3. The epoxy flame-retardant composite material containing the imidazole curing accelerator has good compatibility of the raw materials hexachlorocyclotriphosphazene and imidazole, so that the epoxy resin composite material has more excellent flame-retardant performance.
4. The flame retardant mechanism of the imidazole curing accelerator HIMPH in the condensed phase is that metaphosphoric acid and pyrophosphoric acid generated by pyrolysis have catalytic carbonization effect on an epoxy resin matrix, and the dense expanded carbon residue generated by promotion can obstruct heat transfer, insulate and inhibit volatilization of pyrolysis products so as to achieve the flame retardant effect.
Drawings
FIG. 1 is a FT-IR spectrum of the IM, HCCP feedstocks and the resultant HIMPH product used in example 1 of this invention.
FIG. 2 is an NMR spectrum of a HIMPH product obtained in example 1 of the present invention, wherein (a) is 1 HNMR spectrogram (b) is 31 PNMR spectra.
FIG. 3 is a graph of the Heat Release Rate (HRR) and Total Heat Release (THR) over time for a flame retardant composite of HIMPH/EP obtained with different ratios of the HIMPH addition in various embodiments of the present invention.
FIG. 4 is a differential scanning calorimetry curve and ln (β/Tp2) versus 1/Tp curve for non-isothermal curing of EP (without HIMPH) and HIMPH/EP-1 systems at different ramp rates according to the present invention, wherein: FIG. 4(a) is a DSC curve of EP non-isothermal solidification at different ramp rates, and FIG. 4(b) is a linear fit of ln (. beta./Tp 2) to 1/Tp based on Kissinger's equation according to FIG. 4 (a); FIG. 4(c) is a DSC curve of HIMPH/EP-1 non-isothermal solidification at different ramp rates, and FIG. 4(d) is a linear fit of ln (. beta./Tp 2) to 1/Tp based on Kissinger's equation according to FIG. 4 (c).
Detailed Description
The technical solution of the present invention is described in detail by the following specific examples, which are carried out on the premise of the technical solution of the present invention, and detailed embodiments and specific operation procedures are given, but the scope of the present invention is not limited to the following examples.
The embodiment of the invention provides a preparation method of an epoxy flame-retardant composite material containing an imidazole curing accelerator, which comprises the steps of reacting hexachlorocyclotriphosphazene with imidazole, substituting six chlorine atoms on the hexachlorocyclotriphosphazene by active hydrogen on an imidazole ring to obtain hexaimidazolyl phosphazene (HIMPH), and using the hexaimidazolyl phosphazene (HIMPH) for flame-retardant modification of epoxy resin by a solution blending method to obtain the epoxy flame-retardant composite material containing the imidazole curing accelerator, wherein the flame-retardant performance of the epoxy flame-retardant composite material is improved.
Example 1
Step 1: synthesis of flame-retardant imidazole curing accelerator HIMPH
Imidazole (7.05g) and anhydrous potassium carbonate (2.5g) are added into a 500mL three-neck flask, 100mL tetrahydrofuran is added, air is pumped out by a vacuum pump, and then nitrogen is introduced for protection; HCCP (3g) was dissolved in 50mL of tetrahydrofuran, and then dropped into the imidazole solution through a dropping funnel, followed by stirring at 35 ℃ for 1 hour. And after the reaction is finished, filtering to obtain filtrate, distilling at 35 ℃ under reduced pressure to remove the solvent, washing with tetrahydrofuran for a few times, and finally drying the product in a vacuum oven at 35 ℃ overnight to obtain a white crystal product HIMPH.
Step 2: solution method for preparing HIMPH/EP flame-retardant composite material
Weighing 0.3g of HIMPH, dissolving in a proper amount of dichloromethane, adding 30g of epoxy resin (bisphenol A type epoxy resin E-44) and 25.5g of curing agent methyltetrahydrophthalic anhydride, mixing, mechanically stirring until the solution is clear and transparent, then distilling under reduced pressure at 80 ℃ to remove dichloromethane, pouring the obtained mixture into a mold, defoaming at 80 ℃ in a vacuum oven for 0.5h, curing at 80 ℃ for 1h, and curing at 90 ℃ for 1h to obtain the epoxy flame-retardant composite material containing the imidazole curing accelerator, which is marked as HIMPH/EP-1.
Example 2
In this example, a flame-retardant imidazole-based curing accelerator HIMPH was synthesized and a HIMPH/EP flame-retardant composite was prepared in the same manner as in example 1 except that the amount of HIMPH added in step 2 was 0.77g, and the obtained sample was designated as HIMPH/EP-2.
Example 3
In this example, a flame-retardant imidazole-based curing accelerator HIMPH was synthesized and a HIMPH/EP flame-retardant composite was prepared in the same manner as in example 1 except that the amount of HIMPH added in step 2 was 1.57g, and the obtained sample was designated as HIMPH/EP-3.
Example 4
In this example, a flame-retardant imidazole-based curing accelerator, HIMPH, was synthesized and a HIMPH/EP flame-retardant composite was prepared in the same manner as in example 1, except that the amount of HIMPH added in step 2 was 2.43g, and the obtained sample was designated as HIMPH/EP-4.
Example 5
In this example, a flame-retardant imidazole-based curing accelerator, HIMPH, was synthesized and a HIMPH/EP flame-retardant composite was prepared in the same manner as in example 1, except that the amount of HIMPH added in step 2 was 3.33g, and the obtained sample was designated as HIMPH/EP-5.
Example 6
30g of epoxy resin (bisphenol A type epoxy resin E-44) and 25.5g of curing agent methyltetrahydrophthalic anhydride are mixed and mechanically stirred until the solution is clear and transparent, then methylene dichloride is removed by reduced pressure distillation at 80 ℃, the obtained mixture is poured into a mould, defoamed for 0.5h at 80 ℃ in a vacuum oven, then cured for 1h at 80 ℃, and cured for 1h at 90 ℃, and the epoxy material without the imidazole curing accelerator is obtained and is marked as EP.
FIG. 1 is an infrared spectrum of imidazole, hexachlorocyclotriphosphazene and hexaimidazolphosphazene. The infrared spectrum of HIMPH is 3112, 1520, 1462, 1231 and 863cm -1 The absorption peaks correspond to characteristic peaks of-H, C ═ C bond and C ═ N bond on double bond on five-membered ring in imidazole, and N ═ P bond and N-P bond on nitrogen-phosphorus six-membered ring in hexachlorocyclotriphosphazene. The presence of the characteristic peaks indicates the presence of imidazole and phosphazene rings in the hexaimidazolylphosphazene. Meanwhile, 2500-3100 cm does not exist in the spectrogram of the hexachlorocyclotriphosphazene -1 This peak corresponds to the stretching vibration peak of imidazole structure N-H. And 614 and 532cm present in the HCCP spectrum -1 The characteristic peaks of the P-Cl bond corresponding to the peak also disappear in the spectrum of the hexaimidazolyl phosphazene, and the hexaimidazolyl phosphazene can be successfully synthesized on the initial surface through an infrared spectrogram.
FIG. 2 is an NMR spectrum of hexaimidazolylphosphazene, wherein (a) is 1 H NMR spectrum, (b) is 31 PNMR spectra. In fig. 2(a), the peak at a (7.59ppm) is assigned to the hydrogen atom of-N ═ CH-N-on the imidazole ring, and the peak at b (7.18ppm) is assigned to the hydrogen on the C ═ C double bond, indicating that the imidazole ring structure smoothly enters the hexaimidazolylphosphazene. In FIG. 2(b), the peaks in the plot of hexaimidazolylphosphazene are shifted, indicating a change in the chemical environment of the phosphorus atom in hexaimidazolylphosphazene compared to hexachlorocyclotriphosphazene, while only one peak indicates complete substitution of the chlorine atom of hexachlorocyclotriphosphazene and no disruption of the phosphazene ring. Overall the hexaimidazolylphosphazenes were successfully synthesized.
FIG. 3 is a graph of the Heat Release Rate (HRR) and Total Heat Release (THR) of a flame retardant composite of HIMPH/EP obtained from different proportions of the HIMPH added in each example over time. As can be seen from FIG. 3, the HIMPH/EP composite material has a structure in which the amount of HIMPH added is gradually increasedBoth HRR and THR decrease gradually. The addition of the HIMPH can effectively inhibit the combustion of the composite material and enhance the flame retardance of the material. When the amount of the HIMPH added was 11.1 wt%, the HRR was 701.64kW/m from pure epoxy resin 2 Reduced to 323.36kW/m 2 The reduction is 53.91%. As shown in FIG. 3(b), the total amount of heat release of the epoxy resin composite material can be reduced by adding HIMPH, and when the amount of HIMPH is 5 wt%, the total amount of heat release is minimized to 67.94MJ/m 2 Compared with epoxy resin (99.92 MJ/m) 2 ) The reduction is 32.01%. Indicating that the addition of HIMPH effectively prevented the burning of the epoxy composite.
FIG. 4 is a differential scanning calorimetry curve and ln (. beta./Tp 2) versus 1/Tp curve for non-isothermal solidification of EP (without HIMPH) and HIMPH/EP-1 systems at different ramp rates. FIG. 4(a) is a DSC curve of EP non-isothermal solidification at different ramp rates, and FIG. 4(b) is a linear fit of ln (. beta./Tp 2) to 1/Tp based on Kissinger's equation according to FIG. 4 (a); FIG. 4(c) is a DSC curve of non-isothermal HIMPH/EP-1 solidification at different heating rates, and FIG. 4(d) is a linear fit of ln (. beta./Tp 2) to 1/Tp based on Kissinger's equation according to FIG. 4 (c). The exothermic peaks in fig. 4(a), 4(c) are due to the exotherm during the curing of the epoxy resin. The EP and HIMPH/EP-1 cure systems exhibit similar curing trends as the ramp rate is increased from 5 deg.C/min to 25 deg.C/min. The higher the temperature rise rate, the more intense the curing reaction and the more pronounced the exotherm. Apparent activation energy (E) a ) Reflecting reactivity during curing. E a The lower the curing reactivity, the higher. The E in the curing process can be obtained through calculation of Kissinger equation and linear fitting analysis a . The DSC curve of the non-isothermal solidification of the EP system is shown in FIG. 4(a), and E is obtained by linear fitting of the slope a The value was 75.83 kJ/mol. The DSC curve of the non-isothermal solidification of the HIMPH/EP-1 system is shown in FIG. 4(c), and E is obtained by linear fitting of the slope a The value was 70.64 kJ/mol. DSC tests show that the HIMPH has the function of obviously promoting the curing of an epoxy system.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (8)
1. An epoxy flame-retardant composite material containing imidazole curing accelerator is characterized in that: the epoxy flame-retardant composite material consists of epoxy resin, a curing agent and an imidazole curing accelerator;
the imidazole curing accelerator is hexa-imidazolyl phosphazene with a structural formula shown in a formula (1) obtained by reacting hexachlorocyclotriphosphazene with imidazole and substituting six chlorine atoms on the hexachlorocyclotriphosphazene with active hydrogen on an imidazole ring;
2. the epoxy flame retardant composite of claim 1, wherein: the epoxy resin is at least one of bisphenol A epoxy resin, bisphenol F epoxy resin, phenolic resin and bisphenol S type epoxy resin.
3. The epoxy flame retardant composite of claim 1, wherein: the curing agent is at least one of methyltetrahydrophthalic anhydride, phthalic anhydride and trimellitic anhydride.
4. The epoxy flame-retardant composite material according to claim 1, wherein the imidazole-based curing accelerator, hexaimidazolylphosphazene, is prepared by a method comprising: imidazole and anhydrous potassium carbonate are added into a three-neck flask, tetrahydrofuran is added to serve as a reaction solvent, air is pumped out by a vacuum pump, and then nitrogen is introduced for protection; dissolving hexachlorocyclotriphosphazene in a proper amount of tetrahydrofuran, dripping the solution into an imidazole solution by using a dropping funnel, and stirring and reacting for 1-2 hours at the temperature of 30-35 ℃; and after the reaction is finished, filtering to obtain filtrate, distilling at the temperature of 30-35 ℃ under reduced pressure to remove the solvent, washing with tetrahydrofuran, and finally drying the product in a vacuum oven at the temperature of 30-35 ℃ overnight to obtain white crystal hexaimidazolyl phosphazene.
5. The epoxy flame retardant composite of claim 4, wherein: the mass ratio of imidazole to anhydrous potassium carbonate to hexachlorocyclotriphosphazene is 7-8: 2-3: 3.
6. a method for preparing the epoxy flame-retardant composite material as claimed in any one of claims 1 to 5, characterized in that: dissolving hexaimidazolylphosphazene in a proper amount of dichloromethane, adding epoxy resin and a curing agent, mixing, mechanically stirring until the solution is clear and transparent, then carrying out reduced pressure distillation to remove dichloromethane, pouring the obtained mixture into a mold, carrying out vacuum defoaming, and curing to obtain the epoxy flame-retardant composite material containing the imidazole curing accelerator.
7. The method of claim 6, wherein: the mass ratio of the epoxy resin to the curing agent is 6: 5-5.5; the mass ratio of the hexaimidazolylphosphazene to the epoxy resin is 1-11.5: 100.
8. The method of manufacturing according to claim 6, characterized in that: the temperature of the reduced pressure distillation is 80 ℃; the vacuum defoaming is carried out for 0.5h at 80 ℃; the curing is carried out for 1h at 80 ℃ and then for 1h at 90 ℃.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110066384A (en) * | 2019-04-15 | 2019-07-30 | 广东精铟海洋工程创新研究有限公司 | The preparation method of single-component flame-retardant epoxy resin system, imidazoles latent curing agent and preparation method thereof |
| JP2020200393A (en) * | 2019-06-10 | 2020-12-17 | サンアプロ株式会社 | Epoxy resin curing accelerator and epoxy resin composition |
| CN112194779A (en) * | 2020-10-09 | 2021-01-08 | 江南大学 | Single-component epoxy resin composition containing latent imidazole curing accelerator and preparation method and application thereof |
| CN114181377A (en) * | 2021-12-02 | 2022-03-15 | 常州百思通复合材料有限公司 | Cyclotriphosphazene-based flame-retardant imidazole curing agent and preparation method and application thereof |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110066384A (en) * | 2019-04-15 | 2019-07-30 | 广东精铟海洋工程创新研究有限公司 | The preparation method of single-component flame-retardant epoxy resin system, imidazoles latent curing agent and preparation method thereof |
| JP2020200393A (en) * | 2019-06-10 | 2020-12-17 | サンアプロ株式会社 | Epoxy resin curing accelerator and epoxy resin composition |
| CN112194779A (en) * | 2020-10-09 | 2021-01-08 | 江南大学 | Single-component epoxy resin composition containing latent imidazole curing accelerator and preparation method and application thereof |
| CN114181377A (en) * | 2021-12-02 | 2022-03-15 | 常州百思通复合材料有限公司 | Cyclotriphosphazene-based flame-retardant imidazole curing agent and preparation method and application thereof |
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