CN117466941A - Hydroxyl-containing bivalent phosphorus flame retardant, preparation method thereof and flame-retardant modified epoxy resin - Google Patents
Hydroxyl-containing bivalent phosphorus flame retardant, preparation method thereof and flame-retardant modified epoxy resin Download PDFInfo
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- CN117466941A CN117466941A CN202311428668.1A CN202311428668A CN117466941A CN 117466941 A CN117466941 A CN 117466941A CN 202311428668 A CN202311428668 A CN 202311428668A CN 117466941 A CN117466941 A CN 117466941A
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- 239000003063 flame retardant Substances 0.000 title claims abstract description 164
- 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 146
- 239000003822 epoxy resin Substances 0.000 title claims abstract description 66
- 229920000647 polyepoxide Polymers 0.000 title claims abstract description 66
- 229910052698 phosphorus Inorganic materials 0.000 title claims abstract description 60
- 239000011574 phosphorus Substances 0.000 title claims abstract description 60
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 title claims abstract description 58
- 125000002887 hydroxy group Chemical group [H]O* 0.000 title claims abstract description 35
- 238000002360 preparation method Methods 0.000 title abstract description 24
- RGHHSNMVTDWUBI-UHFFFAOYSA-N 4-hydroxybenzaldehyde Chemical compound OC1=CC=C(C=O)C=C1 RGHHSNMVTDWUBI-UHFFFAOYSA-N 0.000 claims abstract description 56
- DWSWCPPGLRSPIT-UHFFFAOYSA-N benzo[c][2,1]benzoxaphosphinin-6-ium 6-oxide Chemical compound C1=CC=C2[P+](=O)OC3=CC=CC=C3C2=C1 DWSWCPPGLRSPIT-UHFFFAOYSA-N 0.000 claims abstract 6
- 238000001723 curing Methods 0.000 claims description 66
- XEKOWRVHYACXOJ-UHFFFAOYSA-N Ethyl acetate Chemical compound CCOC(C)=O XEKOWRVHYACXOJ-UHFFFAOYSA-N 0.000 claims description 63
- 238000006243 chemical reaction Methods 0.000 claims description 49
- 239000000203 mixture Substances 0.000 claims description 46
- 239000002904 solvent Substances 0.000 claims description 38
- ZMANZCXQSJIPKH-UHFFFAOYSA-N Triethylamine Chemical compound CCN(CC)CC ZMANZCXQSJIPKH-UHFFFAOYSA-N 0.000 claims description 36
- 239000007787 solid Substances 0.000 claims description 35
- 239000003795 chemical substances by application Substances 0.000 claims description 34
- XHXFXVLFKHQFAL-UHFFFAOYSA-N phosphoryl trichloride Chemical compound ClP(Cl)(Cl)=O XHXFXVLFKHQFAL-UHFFFAOYSA-N 0.000 claims description 30
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 claims description 26
- 238000000034 method Methods 0.000 claims description 24
- 238000010438 heat treatment Methods 0.000 claims description 22
- 238000005406 washing Methods 0.000 claims description 22
- QWXYZCJEXYQNEI-OSZHWHEXSA-N intermediate I Chemical compound COC(=O)[C@@]1(C=O)[C@H]2CC=[N+](C\C2=C\C)CCc2c1[nH]c1ccccc21 QWXYZCJEXYQNEI-OSZHWHEXSA-N 0.000 claims description 21
- 239000013067 intermediate product Substances 0.000 claims description 21
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 claims description 20
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 18
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 claims description 18
- 238000001035 drying Methods 0.000 claims description 17
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 14
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 claims description 13
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 13
- WEVYAHXRMPXWCK-UHFFFAOYSA-N Acetonitrile Chemical compound CC#N WEVYAHXRMPXWCK-UHFFFAOYSA-N 0.000 claims description 12
- 239000010413 mother solution Substances 0.000 claims description 11
- 238000001914 filtration Methods 0.000 claims description 10
- 239000003208 petroleum Substances 0.000 claims description 10
- 238000002390 rotary evaporation Methods 0.000 claims description 10
- 239000012046 mixed solvent Substances 0.000 claims description 9
- RYHBNJHYFVUHQT-UHFFFAOYSA-N 1,4-Dioxane Chemical compound C1COCCO1 RYHBNJHYFVUHQT-UHFFFAOYSA-N 0.000 claims description 8
- YMWUJEATGCHHMB-UHFFFAOYSA-N Dichloromethane Chemical compound ClCCl YMWUJEATGCHHMB-UHFFFAOYSA-N 0.000 claims description 6
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 claims description 6
- 238000001704 evaporation Methods 0.000 claims description 6
- 238000002156 mixing Methods 0.000 claims description 6
- 239000012074 organic phase Substances 0.000 claims description 6
- HEDRZPFGACZZDS-UHFFFAOYSA-N Chloroform Chemical compound ClC(Cl)Cl HEDRZPFGACZZDS-UHFFFAOYSA-N 0.000 claims description 4
- 239000007795 chemical reaction product Substances 0.000 claims description 4
- 239000007788 liquid Substances 0.000 claims description 3
- 239000003054 catalyst Substances 0.000 claims description 2
- 230000008020 evaporation Effects 0.000 claims description 2
- 238000013007 heat curing Methods 0.000 claims description 2
- 238000005303 weighing Methods 0.000 claims description 2
- 239000011248 coating agent Substances 0.000 claims 1
- 238000000576 coating method Methods 0.000 claims 1
- 239000000463 material Substances 0.000 abstract description 17
- 230000000694 effects Effects 0.000 abstract description 13
- 125000003118 aryl group Chemical group 0.000 abstract description 7
- 230000002195 synergetic effect Effects 0.000 abstract description 4
- 231100000053 low toxicity Toxicity 0.000 abstract description 3
- 125000001997 phenyl group Chemical group [H]C1=C([H])C([H])=C(*)C([H])=C1[H] 0.000 abstract description 3
- 230000002411 adverse Effects 0.000 abstract description 2
- IBIRZFNPWYRWOG-UHFFFAOYSA-N phosphane;phosphoric acid Chemical compound P.OP(O)(O)=O IBIRZFNPWYRWOG-UHFFFAOYSA-N 0.000 abstract description 2
- 238000003756 stirring Methods 0.000 description 23
- 229910019142 PO4 Inorganic materials 0.000 description 20
- 239000010452 phosphate Substances 0.000 description 20
- 239000012071 phase Substances 0.000 description 16
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 14
- 239000000243 solution Substances 0.000 description 14
- 238000012360 testing method Methods 0.000 description 13
- 238000001816 cooling Methods 0.000 description 9
- ZZTCPWRAHWXWCH-UHFFFAOYSA-N diphenylmethanediamine Chemical compound C=1C=CC=CC=1C(N)(N)C1=CC=CC=C1 ZZTCPWRAHWXWCH-UHFFFAOYSA-N 0.000 description 9
- 238000004090 dissolution Methods 0.000 description 8
- 230000007246 mechanism Effects 0.000 description 8
- 239000008346 aqueous phase Substances 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 7
- 239000005457 ice water Substances 0.000 description 7
- 238000010992 reflux Methods 0.000 description 7
- 238000000926 separation method Methods 0.000 description 7
- 229920000742 Cotton Polymers 0.000 description 6
- 238000005481 NMR spectroscopy Methods 0.000 description 6
- 239000000126 substance Substances 0.000 description 6
- 239000007789 gas Substances 0.000 description 5
- 239000000047 product Substances 0.000 description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical group [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 4
- 230000009286 beneficial effect Effects 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 4
- 238000002485 combustion reaction Methods 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- 238000001228 spectrum Methods 0.000 description 4
- 238000010183 spectrum analysis Methods 0.000 description 4
- 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 3
- 239000012796 inorganic flame retardant Substances 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 230000003647 oxidation Effects 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- 238000000746 purification Methods 0.000 description 3
- 238000011160 research Methods 0.000 description 3
- 238000001644 13C nuclear magnetic resonance spectroscopy Methods 0.000 description 2
- 238000005160 1H NMR spectroscopy Methods 0.000 description 2
- 239000004114 Ammonium polyphosphate Substances 0.000 description 2
- 235000019826 ammonium polyphosphate Nutrition 0.000 description 2
- 229920001276 ammonium polyphosphate Polymers 0.000 description 2
- 238000009835 boiling Methods 0.000 description 2
- 239000006227 byproduct Substances 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000009472 formulation Methods 0.000 description 2
- 238000009776 industrial production Methods 0.000 description 2
- 229910044991 metal oxide Inorganic materials 0.000 description 2
- 150000004706 metal oxides Chemical class 0.000 description 2
- 239000012452 mother liquor Substances 0.000 description 2
- 239000002105 nanoparticle Substances 0.000 description 2
- 239000000376 reactant Substances 0.000 description 2
- 230000000979 retarding effect Effects 0.000 description 2
- 238000003786 synthesis reaction Methods 0.000 description 2
- 238000010998 test method Methods 0.000 description 2
- 239000004593 Epoxy Substances 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- ZTTFLCGNQCKBRY-UHFFFAOYSA-N O=C1c2ccccc2-c2ccccc2P1=O Chemical compound O=C1c2ccccc2-c2ccccc2P1=O ZTTFLCGNQCKBRY-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000009471 action 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
- 239000011230 binding agent Substances 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 239000000571 coke Substances 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010292 electrical insulation Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- -1 flame retardant modified epoxy resins Chemical class 0.000 description 1
- 125000000524 functional group Chemical group 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 1
- IXCSERBJSXMMFS-UHFFFAOYSA-N hydrogen chloride Substances Cl.Cl IXCSERBJSXMMFS-UHFFFAOYSA-N 0.000 description 1
- 229910000041 hydrogen chloride Inorganic materials 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000005764 inhibitory process Effects 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 150000007522 mineralic acids Chemical class 0.000 description 1
- 230000003472 neutralizing effect Effects 0.000 description 1
- 239000012299 nitrogen atmosphere Substances 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 1
- 238000006366 phosphorylation reaction Methods 0.000 description 1
- 239000002861 polymer material Substances 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 238000007086 side reaction Methods 0.000 description 1
- 239000000779 smoke Substances 0.000 description 1
- 238000005979 thermal decomposition reaction Methods 0.000 description 1
- 238000001757 thermogravimetry curve Methods 0.000 description 1
- 229920001187 thermosetting polymer Polymers 0.000 description 1
- 239000004634 thermosetting polymer Substances 0.000 description 1
- ILWRPSCZWQJDMK-UHFFFAOYSA-N triethylazanium;chloride Chemical compound Cl.CCN(CC)CC ILWRPSCZWQJDMK-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- 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 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)
Abstract
The invention discloses a hydroxyl-containing bivalent phosphorus flame retardant, a preparation method thereof and flame-retardant modified epoxy resin, wherein the hydroxyl-containing bivalent phosphorus flame retardant has the following structure:the flame retardant has both low-valence phosphorus (DOPO) with good gas-phase flame retardant effect and high-valence phosphorus (phosphate) with excellent condensed-phase flame retardant effect, and the performance of the flame retardant is enhanced by the synergistic effect of multiple flame retardant effects. Meanwhile, the aromatic benzene ring in the parahydroxybenzaldehyde endows the flame retardant with structural rigidity and good heat resistance, DOPO is introduced through a branch connection point, the generated hydroxyl further enhances the condensed phase flame retardant effect, and meanwhile, the adverse effect of DOPO which is independently used as the flame retardant to the performance of the epoxy resin material is solved, and the compatibility of the flame retardant in the epoxy resin material is enhanced due to the hydroxyl and the aromatic rigid structure. In addition, the flame retardant achieves a UL-94V0 flame retardant rating at an add-on level of 3.7%And belongs to an efficient, low-toxicity, halogen-free and environment-friendly flame retardant.
Description
Technical Field
The invention belongs to the technical field of flame retardants, and particularly relates to a hydroxyl-containing bivalent phosphorus flame retardant, a preparation method thereof and flame-retardant modified epoxy resin.
Background
The statements herein merely provide background information related to the present disclosure and may not necessarily constitute prior art.
As an important thermosetting polymer, the epoxy resin (EP) has the advantages of high mechanical strength, strong adhesive force, chemical corrosion resistance, good electrical insulation property and the like, and is widely applied to the fields of construction, automobiles, electronics, aerospace and the like. However, epoxy resins are inherently flammable, have a low limiting oxygen index, cannot pass the UL-94 burn test, and their widespread use constitutes a great fire threat to human life and property, and the flammability of epoxy resins has severely limited their further use in many fields. Therefore, research on flame retardant modification of epoxy resin is beneficial to promote development of high-performance epoxy resin materials.
Flame retardants for epoxy resins can be classified into inorganic flame retardants and organic flame retardants. The inorganic flame retardant comprises inorganic acid or precursor represented by metal oxide, ammonium polyphosphate and the like, inorganic nano particles and the like, wherein the metal oxide and the inorganic nano particles have the defects of large use amount, low flame retardant efficiency and the like, and the ammonium polyphosphate has the characteristics of poor compatibility, low thermal stability, easiness in hydrolysis and the like, so that the inorganic flame retardant is gradually replaced by the organic flame retardant. In recent years, organophosphorus flame retardants are widely used because of the characteristics of high flame retardant efficiency, molten drop inhibition, low smoke release, low toxicity, environmental friendliness and the like, and gradually take the market dominant position. The flame retardant mechanism of the organophosphorus flame retardant is divided into two types of condensed phase flame retardant and gas phase flame retardant. In the gas phase, phosphorus inhibits flame through a radical trapping mechanism, while in the condensed phase, phosphorus can promote coke formation. Research shows that the oxidation state of phosphorus plays a key role in the chemical mechanism and the flame-retardant action mode of the flame retardant, and the flame retardant gradually changes from gas-phase flame retardance to condensed-phase flame retardance along with the increase of the oxidation state of phosphorus. In addition, the flame retardant effect of phosphorus is related not only to the phosphorus content but also to the chemical environment such as the oxidation valence state of phosphorus, the kind of functional group to which phosphorus is attached, and the like. However, most of the existing organophosphorus flame retardants contain single phosphorus valence state, and it is difficult to consider two flame retarding mechanisms of gas phase and condensed phase, and the chemical environment such as a phosphorus connecting group is not optimized, which is unfavorable for researching and developing high-performance organophosphorus flame retardants.
9, 10-dihydro-9-oxo-10-phosphaphenanthrene-10-oxide (DOPO) and its derivatives have attracted considerable attention from researchers due to their excellent gas fire resistance properties. However, DOPO relying on a single flame retardant mechanism requires a large amount of addition to achieve good flame retardant results. Only a few efforts are focused on developing high-efficiency DOPO derivatives at present, and there is no research on the structure of high-performance DOPO derivatives with multiple flame retarding mechanisms.
Disclosure of Invention
Aiming at the defects existing in the prior art, the invention aims to provide a hydroxyl-containing bivalent phosphorus flame retardant, a preparation method thereof and flame-retardant modified epoxy resin, so as to solve the problem of flammability of an epoxy resin material.
The invention provides a hydroxyl-containing double-valence phosphorus flame retardant and a preparation method thereof, and the hydroxyl-containing double-valence phosphorus flame retardant is applied to flame-retardant modified epoxy resin materials based on high reactivity of P-Cl and P-H bonds, wherein phosphate containing phosphorus (5 valence) is taken as a framework, P-Hydroxybenzaldehyde (HBA) is taken as a branch connection point, and phosphorus (3 valence) DOPO is introduced into a flame retardant structure. The flame retardant has both low-valence phosphorus (DOPO) with good gas-phase flame retardant effect and high-valence phosphorus (phosphate) with excellent condensed-phase flame retardant effect, and the performance of the flame retardant is enhanced by the synergistic effect of multiple flame retardant effects. Meanwhile, the aromatic benzene ring in the parahydroxybenzaldehyde endows the flame retardant with structural rigidity and good heat resistance, DOPO is introduced through a branch connection point, the generated hydroxyl further enhances the condensed phase flame retardant effect, and meanwhile, the adverse effect of DOPO which is independently used as the flame retardant to the performance of the epoxy resin material is solved, and the compatibility of the flame retardant in the epoxy resin material is enhanced due to the hydroxyl and the aromatic rigid structure. In addition, the preparation process of the flame retardant is simple, green and environment-friendly, does not need a complex post-treatment process, has the synthesis yield of more than 85 percent, and is easy to realize industrial production.
In order to achieve the above object, the present invention is realized by the following technical scheme:
in a first aspect, the present invention provides a hydroxyl-containing bis-valent phosphorus flame retardant having the structure shown below:
in a second aspect, the invention provides a preparation method of the hydroxyl-containing bivalent phosphorus flame retardant, which comprises the following steps:
adding p-hydroxybenzaldehyde and triethylamine into tetrahydrofuran according to a proportion, uniformly mixing, and then dropwise adding phosphorus oxychloride at a low temperature to perform a first reaction;
after the reaction is finished, evaporating to remove the solvent, adding ethyl acetate to the reaction product for redissolution, washing with water, separating liquid to obtain an organic phase, concentrating the organic phase to obtain a mother solution, dropwise adding a mixed solvent of ethyl acetate and petroleum ether into the mother solution, and separating out an intermediate product I;
adding the intermediate product I and DOPO into a solvent in a molar ratio of 1:3-3.6, and carrying out a second reaction at 85-110 ℃ for 6-8h;
after the reaction is finished, removing the solvent, and purifying the solid to obtain the catalyst.
The molar ratio of intermediate I to DOPO includes, but is not limited to, 1:3, 1:3.1, 1:3.2, 1:3.3, 1:3.4, 1:3.5, 1:3.6, and the like.
The reaction temperature of the second reaction includes, but is not limited to, 85 ℃, 87 ℃, 88 ℃, 89 ℃, 90 ℃, 92 ℃, 93 ℃, 95 ℃, 96 ℃, 97 ℃, 100 ℃, 102 ℃, 104 ℃, 106 ℃, 109 ℃, 110 ℃, etc.
The triethylamine is used as an acid binding agent for neutralizing hydrogen chloride generated in a reaction system so as to promote the reaction.
Tetrahydrofuran only acts as a solvent in the reaction system to dissolve the reactants and provide an environment for interaction between the reactants.
After the reaction is finished, evaporating to remove the solvent, adding ethyl acetate for dissolution, and dissolving the rotary evaporation product in a good solvent which is not mutually soluble with water for subsequent enrichment and purification of the intermediate product I.
After the reaction is finished and the solvent is removed by evaporation, the reaction product comprises an intermediate product I and other water-soluble byproducts; adding ethyl acetate to redissolve the reaction product, washing with water, transferring water-soluble byproducts such as triethylamine hydrochloride in the product into water, separating and removing water phase by separating liquid, leaving organic phase, and adopting the method to realize the primary purification of the intermediate product I. And concentrating the organic phase to obtain mother liquor, adding a poor solvent prepared by ethyl acetate and petroleum ether according to a certain proportion into the mother liquor to separate out an intermediate product I, and finally purifying the intermediate product I and improving the yield.
The intermediate product I has the following chemical structural formula:
the preparation reaction process is as follows:
in some embodiments, the molar ratio of parahydroxyben-zaldehyde to triethylamine is 1:1-1.5. This includes, but is not limited to, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, and the like.
Preferably, the mass ratio of tetrahydrofuran to p-hydroxybenzaldehyde is 8-15:1. This includes, but is not limited to, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, and the like.
Preferably, the molar ratio of phosphorus oxychloride to parahydroxyben-zaldehyde is 1:3-4. This includes, but is not limited to, 1:3, 1:3.1, 1:3.2, 1:3.3, 1:3.4, 1:3.5, 1:3.6, 1:3.7, 1:3.8, 1:3.9, 1:4, and the like.
In some embodiments, the temperature at which phosphorus oxychloride is added dropwise is-2 to 5 ℃, such as may be-2 ℃, 0 ℃,1 ℃, 2 ℃,3 ℃,5 ℃, preferably 0 ℃.
The reaction between phosphorus oxychloride and p-hydroxybenzaldehyde is exothermic, and the reaction is more severe under the condition of higher temperature, so that the temperature of a reaction system is easy to be rapidly increased, and the temperature exceeds a reasonable temperature interval, so that side reactions are easy to occur. Therefore, in order to avoid this, the reaction system should be kept at a low temperature when phosphorus oxychloride is added dropwise.
In some embodiments, the method of evaporating the removal solvent is rotary evaporation.
In some embodiments, the solvent added in the second reaction is selected from acetonitrile, dioxane, dimethylformamide (DMF) or toluene.
Preferably, in the second reaction, the molar ratio of intermediate I to DOPO is 1:3.
In some embodiments, the method of purifying the solid is: and dissolving the obtained solid by using a solvent, then recrystallizing, filtering, washing and drying to obtain the pure flame retardant.
Preferably, the solvent for washing the solid is one or a combination of methanol, ethanol, methylene chloride, chloroform or dioxane.
Preferably, the solvent used for the washing is ethanol.
Ethanol is used as a good solvent and a low boiling point solvent of DOPO as raw materials, is used for dissolving and removing the residual DOPO in a reaction system in a filtering operation, and can replace the high boiling point solvent, thereby being beneficial to drying the product.
In a third aspect, the invention provides a flame-retardant modified epoxy resin, which comprises the following components in parts by mass: 73-78 parts of epoxy resin, 18-21 parts of curing agent and 1-9 parts of flame retardant.
In a fourth aspect, the invention provides a method for preparing the flame-retardant modified epoxy resin, comprising the following steps:
weighing epoxy resin, curing agent and flame retardant in proportion;
adding a flame retardant into epoxy resin at 100-115 ℃, uniformly mixing, vacuumizing to remove bubbles, and obtaining a first-grade mixture;
and adding the curing agent into the primary mixture, and uniformly mixing to obtain the secondary mixture.
In some embodiments, the method further comprises the step of injecting the secondary mix into a mold to thermally cure the secondary mix to produce the target part.
Preferably, the method of heat curing is as follows: heating and curing for 1-3h at 80-100 ℃, and then curing for 4-8h at 140-150 ℃.
The beneficial effects achieved by one or more embodiments of the present invention described above are as follows:
the hydroxyl-containing double-valence phosphorus flame retardant provided by the invention contains +3 and +5 double-valence phosphorus elements, and combines the gas-phase flame retardant effect of low-valence phosphorus and the condensed-phase flame retardant effect of high-valence phosphorus, so that the synergistic flame retardant mechanism effectively improves the flame retardant property of an epoxy resin material, and the flame retardant grade reaches UL-94V0 when the synergistic flame retardant mechanism is added into the epoxy resin material in a weight percentage of 3.7%, thus the hydroxyl-containing double-valence phosphorus flame retardant belongs to an efficient, low-toxicity and halogen-free environment-friendly flame retardant.
The hydroxyl-containing bivalent phosphorus flame retardant provided by the invention contains hydroxyl groups and an aromatic rigid structure, the hydroxyl groups and the flame retardant can be subjected to phosphorylation reaction to improve the heat stability of the flame retardant, the aromatic benzene ring structure also further improves the temperature resistance of the flame retardant, and the molecular structure design not only enhances the compatibility with an epoxy resin material, but also is beneficial to increasing the char formation amount of the epoxy resin material at high temperature.
The preparation method of the flame retardant provided by the invention can be obtained through two steps of reactions, the reaction process is easy to control, the synthesis process is simple, the post-treatment processes such as product purification and the like are easy to carry out, the product yield can reach more than 85%, and the industrial production is easy.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention.
FIG. 1 shows the intermediate product I according to example 1 of the invention 1 H-NMR nuclear magnetic spectrum;
FIG. 2 shows the intermediate product I according to example 1 of the invention 13 C-NMR nuclear magnetic spectrum;
FIG. 3 shows DOPO-phosphonates prepared in the examples of the present invention 1 H-NMR nuclear magnetic spectrum;
FIG. 4 shows DOPO-phosphonates prepared in the examples of the present invention 13 C-NMR nuclear magnetic spectrum;
FIG. 5 shows two organic flame retardants containing phosphorus in different valence states;
FIG. 6 is DOPO-phosphate, OPPh 3 Thermal gravimetric TGA profile of DOPO-HBA;
FIG. 7 is a thermogravimetric TGA graph of an epoxy resin and its flame retardant composite.
Detailed Description
It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the invention. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
The invention is further illustrated in the following figures and examples, which are not to be construed as limiting the scope of the invention.
Example 1
(1) Preparation of intermediate I
9.24g of p-Hydroxybenzaldehyde (HBA) and 10.5ml of triethylamine were added to 90ml of tetrahydrofuran, stirred at room temperature for 30 minutes, and then 3.52g of phosphorus oxychloride was slowly added dropwise under ice water bath conditions. After the dripping is finished, the room temperature is restored to continue the reaction for 2 hours. 5ml of dilute sulfuric acid solution (0.1 mol/L H) are added 2 SO 4 ) After the reaction was completed, the solvent was removed by rotary evaporation, then 50ml of ethyl acetate was added for dissolution, further washing with water, and the aqueous phase was removed by separation, and the resulting organic solution was purified by MgSO 4 Drying, concentrating to obtain mother solution, and slowly dripping mixed solvent (ethyl acetate/petroleum ether=1:4) until solid is completely separated out, filtering, washing and drying the separated white solid to obtain pure intermediate product I.
The chemical structural formula of the intermediate product I is as follows:
the white intermediate I prepared in this example was subjected to 1 H NMR(400MHz,CDCl 3 ) And (5) nuclear magnetic spectrum analysis. As shown in fig. 1, the peak δ (ppm) corresponds to the following: delta 10.02 (s, 3H), 7.97-7.95 (d, 6H), 7.46-7.44 (d, 6H), which corresponds to the number of hydrogens of intermediate product I.
The white intermediate I prepared in this example was subjected to 13 C NMR(101MHz,CDCl 3 ) And (5) nuclear magnetic spectrum analysis. As shown in fig. 2, the peak δ (ppm) corresponds to the following: 190.45,154.34,134.20,131.91,120.70, which corresponds to the number of carbons in the intermediate I.
(2) Preparation of hydroxy-containing bis-valent phosphorus flame retardants
8g of intermediate I and 12.66g of DOPO were added to 100ml of dioxane and the reaction was stirred at 110℃for 8h under reflux. After the reaction, the solvent was removed, and the obtained solid was recrystallized from 25ml of methanol, and the precipitated white solid was filtered, washed and dried to obtain flame retardant DOPO-phosphate with a yield of 82%.
The structural formula of the hydroxyl-containing bivalent phosphorus flame retardant is as follows:
example 2
(1) Preparation of intermediate I
9.24g of p-Hydroxybenzaldehyde (HBA) and 10ml of triethylamine were added to 100ml of tetrahydrofuran, stirred at room temperature for 30 minutes, and then 3.31g of phosphorus oxychloride was slowly added dropwise under ice water bath conditions. After the dripping is finished, the room temperature is restored to continue the reaction for 2 hours. 5ml of dilute sulfuric acid solution (0.1 mol/L H) are added 2 SO 4 ) After the reaction was completed, the solvent was removed by rotary evaporation, then 50ml of ethyl acetate was added for dissolution, further washing with water, and the aqueous phase was removed by separation, and the resulting organic solution was purified by MgSO 4 Drying, concentrating to obtain mother solution, and slowly dripping mixed solvent (ethyl acetate/petroleum ether=1:4) until solid is completely separated out, filtering, washing and drying the separated white solid to obtain pure intermediate product I.
(2) Preparation of hydroxy-containing bis-valent phosphorus flame retardants
8g of intermediate I and 12.66g of DOPO were added to 130ml of acetonitrile and reacted at 110℃under reflux with stirring for 6h. After the reaction is finished, the solvent is removed, the obtained solid is recrystallized by using 25ml of ethanol, and the precipitated white solid is filtered, washed and dried to obtain the flame retardant DOPO-phosphate with the yield of 85 percent.
Example 3
(1) Preparation of intermediate I
9.04g of p-Hydroxybenzaldehyde (HBA) and 10.1ml of triethylamine were added to 94ml of tetrahydrofuran, stirred at room temperature for 25 minutes, and then 3.5g of phosphorus oxychloride was slowly added dropwise under ice water bath conditions. After the dripping is finished, the room temperature is restored to continue the reaction for 2.3 hours. 5ml of dilute sulfuric acid solution (0.1 mol/L H) are added 2 SO 4 ) After the reaction was completed, the solvent was removed by rotary evaporation, then 50ml of ethyl acetate was added for dissolution, further washing with water, and the aqueous phase was removed by separation, and the resulting organic solution was purified by MgSO 4 Drying, concentrating to obtain mother solution, and slowly dripping mixed solvent (ethyl acetate/petroleum ether=1:4) until solid is completely separated out, filtering, washing and drying the separated white solid to obtain pure intermediate product I.
(2) Preparation of hydroxy-containing bis-valent phosphorus flame retardants
8g of intermediate I and 12.66g of DOPO were added to 110ml of DMF and reacted at 85℃under reflux with stirring for 6h. After the reaction is finished, the solvent is removed, the obtained solid is recrystallized by 25ml dioxane, and the precipitated white solid is filtered, washed and dried to obtain the flame retardant DOPO-phosphate with the yield of 87 percent.
Example 4
(1) Preparation of intermediate I
9.26g of p-Hydroxybenzaldehyde (HBA) and 10ml of triethylamine are added into 95ml of tetrahydrofuran, stirred for 30min at normal temperature, and then slowly added dropwise under ice water bath condition for 3.22g of phosphorus oxychloride. After the dripping is finished, the room temperature is restored to continue the reaction for 2 hours. 5ml of dilute sulfuric acid solution (0.1 mol/L H) are added 2 SO 4 ) After the reaction was completed, the solvent was removed by rotary evaporation, then 50ml of ethyl acetate was added for dissolution, further washing with water, and the aqueous phase was removed by separation, and the resulting organic solution was purified by MgSO 4 Drying, concentrating to obtain mother solution, and slowly dripping mixed solvent (ethyl acetate/petroleum ether=1:4) until solid is completely separated out, filtering, washing and drying the separated white solid to obtain pure intermediate product I.
(2) Preparation of hydroxy-containing bis-valent phosphorus flame retardants
8g of intermediate I and 12.66g of DOPO were added to 65ml of DMF and reacted at 95℃under reflux with stirring for 7h. After the reaction, the solvent is removed, the obtained solid is recrystallized by 25ml of methanol, and the precipitated white solid is filtered, washed and dried to obtain the flame retardant DOPO-phosphate with the yield of 90 percent.
Example 5
(1) Preparation of intermediate I
9.15g of p-Hydroxybenzaldehyde (HBA) and 10ml of triethylamine were added to 90ml of tetrahydrofuran, stirred at room temperature for 30 minutes, and then 3.58g of phosphorus oxychloride was slowly added dropwise under ice water bath conditions. After the dripping is finished, the room temperature is restored to continue the reaction for 2 hours. 5ml of dilute sulfuric acid solution (0.1 mol/L H) are added 2 SO 4 ) After the reaction was completed, the solvent was removed by rotary evaporation, then 50ml of ethyl acetate was added for dissolution, further washing with water, and the aqueous phase was removed by separation, and the resulting organic solution was purified by MgSO 4 Drying, concentrating to obtain mother solution, and slowly dripping mixed solvent (ethyl acetate/petroleum ether=1:4) until solid is completely separated out, filtering, washing and drying the separated white solid to obtain pure intermediate product I.
(2) Preparation of hydroxy-containing bis-valent phosphorus flame retardants
8g of intermediate I and 12.66g of DOPO were added to 110ml of DMF and reacted at 110℃under reflux with stirring for 7h. After the reaction, the solvent is removed, the obtained solid is recrystallized by 25ml of methanol, and the precipitated white solid is filtered, washed and dried to obtain the flame retardant DOPO-phosphate with the yield of 88 percent.
Example 6
(1) Preparation of intermediate I
9.15g of p-Hydroxybenzaldehyde (HBA) and 10.5ml of triethylamine were added to 80ml of tetrahydrofuran, stirred at room temperature for 40 minutes, and then 3.61g of phosphorus oxychloride was slowly added dropwise under ice water bath conditions. After the dripping is finished, the room temperature is restored to continue the reaction for 2 hours. 5ml of dilute sulfuric acid solution (0.1 mol/L H) are added 2 SO 4 ) After the reaction was completed, the solvent was removed by rotary evaporation, then 50ml of ethyl acetate was added for dissolution, further washing with water, and the aqueous phase was removed by separation, and the resulting organic solution was purified by MgSO 4 Drying, concentrating to obtain mother solution, and slowly dripping mixed solvent (ethyl acetate/petroleum ether=1:4) until solid is completely separated out, filtering, washing and drying the separated white solid to obtain pure intermediate product I.
(2) Preparation of hydroxy-containing bis-valent phosphorus flame retardants
8g of intermediate I and 12.66g of DOPO were added to 85ml of acetonitrile and reacted at 85℃under reflux with stirring for 8h. After the reaction, the solvent is removed, the obtained solid is recrystallized by 25ml dioxane, and the separated white solid is filtered, washed and dried to obtain the flame retardant DOPO-phosphate with the yield of 84 percent.
Example 7
(1) Preparation of intermediate I
9.26g of p-Hydroxybenzaldehyde (HBA) and 10.7ml of triethylamine were added to 85ml of tetrahydrofuran, stirred at room temperature for 35 minutes, and then 3.43g of phosphorus oxychloride was slowly added dropwise under ice water bath conditions. After the completion of the dropwise addition, the reaction was continued at room temperature for 2.5 hours. 5ml of dilute sulfuric acid solution (0.1 mol/L H) are added 2 SO 4 ) After the reaction was completed, the solvent was removed by rotary evaporation, then 50ml of ethyl acetate was added for dissolution, further washing with water, and the aqueous phase was removed by separation, and the resulting organic solution was purified by MgSO 4 Drying, concentrating to obtain mother solution, and slowly dripping mixed solvent (ethyl acetate/petroleum ether=1:4) until solid is completely separated out, filtering, washing and drying the separated white solid to obtain pure intermediate product I.
(2) Preparation of hydroxy-containing bis-valent phosphorus flame retardants
8g of intermediate I and 12.66g of DOPO were added to 60ml of dioxane and reacted at 95℃under reflux with stirring for 6h. After the reaction, the solvent is removed, the obtained solid is recrystallized by 25ml of methanol, and the precipitated white solid is filtered, washed and dried to obtain the flame retardant DOPO-phosphate with the yield of 85 percent.
FIGS. 3 and 4 are divided into flame retardant DOPO-phosphonates 1 H NMR 13 The analysis results of the C NMR chart, FIG. 3 and FIG. 4 are shown below.
1 H NMR(400MHz,CDCl 3 ) And (5) nuclear magnetic spectrum analysis. The peak delta (ppm) corresponds to the following: delta 8.21-8.0 (m, 8H), 7.81-7.76 (m, 3H), 7.63-7.61 (t, 1H), 7.49-7.37 (m, 12H), 7.29-7.16 (m, 12H), 6.56-6.45 (d, 3H) and 5.26-5.46 (t, 3H) are matched with the number of DOPO-phosphorus hydrogen of the flame retardant.
13 C NMR(101MHz,CDCl 3 ) And (5) nuclear magnetic spectrum analysis. The peak delta (ppm) corresponds to the following: 150.62,150.54,150.48,149.80,136.64,135.27,135.16,134.26,134.09,132.06,131.55,131.49,131.21,131.00,129.70,129.34,129.00,128.92,128.60,128.52,125.99,125.77,124.87,124.62,124.34,124.27,124.04,123.98,123.27,122.63,122.52,121.96,121.90,121.68,121.62,120.14,120.09,119.92,119.81,72.04,71.77,71.27,71.01, which corresponds to the number of DOPO-phosphate carbons as a flame retardant.
The flame retardant DOPO-phosphate and the flame retardant of the control group (DOPO-HBA and OPPh) prepared in the example 3 ) The results of the thermogravimetric TGA are shown in FIG. 6, wherein the control group flame retardants DOPO-HBA and OPPh 3 Are all flame retardants containing phosphorus in a monovalent state and different from the DOPO-phosphorus structure, and the molecular structure is shown in figure 5, so that the structural characteristics of the flame retardant DOPO-phosphorus are studied. From the test results, the carbon residue rates of the three flame retardants at 800 ℃ are respectively: 34.7% DOPO-phosphate, 14.2% DOPO-HBA, OPPh 3 0.99%, wherein the flame retardant DOPO-phosphorus has the highest carbon residue rate at 800 ℃, the result shows that the flame retardant with the rigid aromatic type multivalent phosphorus structure has good thermal stability.
The hydroxyl-containing double-valence phosphorus flame retardant is used for preparing the flame-retardant modified epoxy resin material.
Example 9
1) 75g of epoxy resin, 19g of diaminodiphenyl methane (DDM) curing agent and 3.6g of DOPO-phosphate flame retardant are weighed;
2) Adding a flame retardant into the epoxy resin at 110 ℃, uniformly stirring, and vacuumizing to remove bubbles to obtain a primary mixture;
3) Adding a curing agent into the primary mixture at 110 ℃, and rapidly stirring to fully dissolve the curing agent into a uniform system to obtain a secondary mixture;
4) Injecting the secondary mixture into a mold, putting the mold into an oven, controlling the heating temperature to 80 ℃ for curing for 2 hours, controlling the heating temperature to 150 ℃ for curing for 6 hours, and naturally cooling to room temperature after curing to obtain the flame-retardant modified epoxy resin.
Example 10
1) 75g of epoxy resin, 20g of diaminodiphenyl methane (DDM) curing agent and 4g of DOPO-phosphate flame retardant are weighed;
2) Adding a flame retardant into the epoxy resin at 112 ℃, uniformly stirring, and vacuumizing to remove bubbles to obtain a primary mixture;
3) Adding a curing agent into the primary mixture at 112 ℃, and rapidly stirring to fully dissolve the curing agent into a uniform system to obtain a secondary mixture;
4) Injecting the secondary mixture into a mold, putting the mold into an oven, controlling the heating temperature to 90 ℃ for curing for 3 hours, controlling the heating temperature to 145 ℃ for curing for 8 hours, and naturally cooling to room temperature after curing to obtain the flame-retardant modified epoxy resin.
Example 11
1) 78g of epoxy resin, 18g of diaminodiphenyl methane (DDM) curing agent and 6g of DOPO-phosphate flame retardant are weighed;
2) Adding a flame retardant into 115 ℃ epoxy resin, uniformly stirring, and vacuumizing to remove bubbles to obtain a primary mixture;
3) Adding the curing agent into the primary mixture at 115 ℃ and rapidly stirring to fully dissolve the curing agent into a uniform system to obtain a secondary mixture;
4) Injecting the secondary mixture into a mold, putting the mold into an oven, controlling the heating temperature to 90 ℃ for curing for 1h, controlling the heating temperature to 145 ℃ for curing for 4h, and naturally cooling to room temperature after curing to obtain the flame-retardant modified epoxy resin.
Example 12
1) 75g of epoxy resin, 18g of diaminodiphenyl methane curing agent and 6g of DOPO-phosphate flame retardant are weighed;
2) Adding a flame retardant into the epoxy resin at 112 ℃, uniformly stirring, and vacuumizing to remove bubbles to obtain a primary mixture;
3) Adding the curing agent into the primary mixture at 115 ℃ and rapidly stirring to fully dissolve the curing agent into a uniform system to obtain a secondary mixture;
4) Injecting the secondary mixture into a mold, putting the mold into an oven, controlling the heating temperature to be 85 ℃ for curing for 3 hours, controlling the heating temperature to be 145 ℃ for curing for 4 hours, and naturally cooling to room temperature after curing is finished to obtain the flame-retardant modified epoxy resin.
Example 13
1) 78g of epoxy resin, 21g of diaminodiphenyl methane (DDM) curing agent and 9g of DOPO-phosphate flame retardant are weighed;
2) Adding a flame retardant into 115 ℃ epoxy resin, uniformly stirring, and vacuumizing to remove bubbles to obtain a primary mixture;
3) Adding the curing agent into the primary mixture at 115 ℃ and rapidly stirring to fully dissolve the curing agent into a uniform system to obtain a secondary mixture;
4) Injecting the secondary mixture into a mold, putting the mold into an oven, controlling the heating temperature to be 95 ℃ for curing for 1h, controlling the heating temperature to be 145 ℃ for curing for 8h, and naturally cooling to room temperature after curing is finished to obtain the flame-retardant modified epoxy resin.
Example 14
1) 80g of epoxy resin, 20g of diaminodiphenyl methane (DDM) curing agent and 5g of DOPO-phosphate flame retardant are weighed;
2) Adding a flame retardant into the epoxy resin at 110 ℃, uniformly stirring, and vacuumizing to remove bubbles to obtain a primary mixture;
3) Adding the curing agent into the primary mixture at 115 ℃ and rapidly stirring to fully dissolve the curing agent into a uniform system to obtain a secondary mixture;
4) Injecting the secondary mixture into a mold, putting the mold into an oven, controlling the heating temperature to be 97 ℃ for curing for 2 hours, controlling the heating temperature to be 150 ℃ for curing for 7 hours, and naturally cooling to room temperature after curing is finished to obtain the flame-retardant modified epoxy resin.
Comparative example 1
1) 75g of epoxy resin and 19g of diaminodiphenyl methane curing agent are weighed;
2) Adding the curing agent into the primary mixture at 110 ℃, and rapidly stirring to fully dissolve the curing agent into a uniform system to obtain the mixture;
3) Injecting the mixture into a mold, putting the mold into an oven, controlling the heating temperature to 80 ℃ for curing for 2 hours, controlling the heating temperature to 150 ℃ for curing for 6 hours, and naturally cooling to room temperature after curing to obtain the flame-retardant modified epoxy resin.
Comparative example 2
1) 75g of epoxy resin, 19g of diaminodiphenyl methane curing agent and 4.53g of DOPO-HBA flame retardant are weighed;
2) Adding a flame retardant into the epoxy resin at 110 ℃, uniformly stirring, and vacuumizing to remove bubbles to obtain a primary mixture;
3) Adding a curing agent into the primary mixture at 110 ℃, and rapidly stirring to fully dissolve the curing agent into a uniform system to obtain a secondary mixture;
4) Injecting the secondary mixture into a mold, putting the mold into an oven, controlling the heating temperature to 80 ℃ for curing for 2 hours, controlling the heating temperature to 150 ℃ for curing for 6 hours, and naturally cooling to room temperature after curing to obtain the flame-retardant modified epoxy resin.
Comparative example 3
1) 75g of epoxy resin, 19g of diaminodiphenylmethane curing agent and OPPh were weighed out 3 4.37g of flame retardant;
2) Adding a flame retardant into the epoxy resin at 110 ℃, uniformly stirring, and vacuumizing to remove bubbles to obtain a primary mixture;
3) Adding a curing agent into the primary mixture at 110 ℃, and rapidly stirring to fully dissolve the curing agent into a uniform system to obtain a secondary mixture;
4) Injecting the secondary mixture into a mold, putting the mold into an oven, controlling the heating temperature to 80 ℃ for curing for 2 hours, controlling the heating temperature to 150 ℃ for curing for 6 hours, and naturally cooling to room temperature after curing to obtain the flame-retardant modified epoxy resin.
Thermal weight TGA and UL-94 vertical burn tests were performed on the flame retardant modified epoxy resins obtained in examples and comparative examples, and the results are shown in table 1 and fig. 7.
Table 1 formulation of phosphorus flame retardant modified epoxy resin material and flame retardant properties thereof
In table 1, the test method for each performance parameter is as follows:
phosphorus content testing method:
the phosphorus content refers to the mass percentage of phosphorus element contained in the organic phosphorus flame retardant added in the initial formula to the whole formula, and the calculation formula is as follows:
wherein m is (flame retardant) The amount of flame retardant added to the formulation;
M (flame retardant) Is the relative molecular mass of the flame retardant, wherein M (DOPO-phosphate) ＝1089.2，M (DOPO-HBA) ＝338.1，M (OPPh3) ＝326.1；
m Total (S) Is the mass combination of epoxy resin, DDM curing agent and flame retardant.
Carbon residue amount test method:
and (3) characterizing the thermal decomposition process of the sample by adopting a thermogravimetric analyzer (TGA), and obtaining a curve of the weight of the sample along with the temperature under certain program conditions, wherein the ratio of the residual mass of the curve at 800 ℃ to the initial sample amount is the carbon residue amount.
The test conditions are that the initial temperature is kept at 50 ℃ for 5min under the nitrogen atmosphere, the heating rate is 10 ℃/min, and the temperature is increased to 800 ℃. The mass of the sample is 5-10mg.
UL-94 rating was used to evaluate the flammability performance of materials, the vertical burn test of which was carried out according to standard GBT2408-2008
The row test comprises the following specific steps:
(1) The upper end of the sample bar (130 mm. Times.13 mm) was clamped to a length of 6mm, and the vertical axis was vertical, so that the lower end of the sample was 300mm higher than the horizontal cotton layer, and the size of the cotton layer was approximately 50 mm. Times.50 mm. Times.6 mm.
(2) The burner tube was placed away from the sample and the burner was adjusted to produce a standard-compliant test flame. Wait for 5min to stabilize the status of the torch.
(3) The flame center was added to the midpoint of the bottom edge of the specimen while keeping the torch tip 10mm lower than this point for 10s. Immediately after the flame was applied to the sample for 10 seconds, the torch was removed and the after-flame time t was measured using a timer 1 In seconds.
(4) When the after flame of the sample was extinguished, the test flame was immediately replaced under the sample, and the top end of the torch was kept at a distance of 10mm below the bottom end of the sample for 10s. Immediately after the second flame application to the sample for 10 seconds, the burner was removed and the after-flame time t was measured using a timer 2 Sum afterglow time t 3 . While note and record if any particles were falling from the sample and observe if the cotton pad was ignited.
Wherein NR, V-0, V-1 and V-2 have the meanings given in the following, respectively:
NR means no rating;
v-0: after the sample is subjected to two combustion tests for 10 seconds, the flame is extinguished within 10 seconds, and after the flame is applied for the second time, the after-flame of a single sample is added with afterglow time for not more than 30 seconds, and no combustion matters fall down or cannot ignite the cotton pad;
v-1: after the sample is subjected to two combustion tests for 10 seconds, the flame is extinguished within 30 seconds, and after the flame is applied for the second time, the after-flame of a single sample is added with afterglow time not longer than 60 seconds, and no combustion matters fall down or cannot ignite the cotton pad;
v-2: after two 10 second burn tests were performed on the samples, the flame extinguished within 30 seconds, and after the second flame application, the after flame plus the afterglow time of the individual samples was no more than 60 seconds, with the burn falling or the burn being able to ignite the cotton pad.
The thermal stability and flame retardant properties of the epoxy resin materials modified by different phosphorus-containing flame retardants prepared in this example are shown in table 1 and fig. 7, and under the condition that the phosphorus element addition amounts are the same, the test results of the different epoxy resin material formulas are as follows:
the char yield at 800℃and the UL-94 result were respectively: examples were all above 27.9% and V-0 grade, comparative example 1 was 21.0%, comparative example 2 was 25.8% and V-0 grade, and comparative example 3 was 24.8% and V-1 grade, with the example DOPO-phosphate modified epoxy resin material having the highest char yield and V-0 flame retardant rating, indicating that a multivalent phosphorus flame retardant with a gas phase and condensed phase flame retardant mode synergy imparts superior thermal stability and flame retardant properties to the epoxy polymer material compared to a monovalent phosphorus flame retardant with one flame retardant mode.
The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A hydroxyl-containing bivalent phosphorus flame retardant is characterized in that: the structure is as follows:
2. the method for preparing the hydroxyl-containing bi-valence phosphorus flame retardant according to claim 1, which is characterized in that: the method comprises the following steps:
adding p-hydroxybenzaldehyde and triethylamine into tetrahydrofuran according to a proportion, uniformly mixing, and then dropwise adding phosphorus oxychloride at a low temperature to perform a first reaction;
after the reaction is finished, evaporating to remove the solvent, adding ethyl acetate to the reaction product for redissolution, washing with water, separating liquid to obtain an organic phase, concentrating the organic phase to obtain a mother solution, dropwise adding a mixed solvent of ethyl acetate and petroleum ether into the mother solution, and separating out an intermediate product I;
adding the intermediate product I and DOPO into a solvent in a molar ratio of 1:3-3.6, and carrying out a second reaction at 85-110 ℃ for 6-8h;
after the reaction is finished, removing the solvent, and purifying the solid to obtain the catalyst.
3. The method for preparing the hydroxyl-containing bi-valence phosphorus flame retardant according to claim 2, wherein: the molar ratio of the parahydroxyben-zaldehyde to the triethylamine is 1:1-1.5;
preferably, the mass ratio of tetrahydrofuran to p-hydroxybenzaldehyde is 8-15:1;
further preferably, the mass ratio of tetrahydrofuran to p-hydroxybenzaldehyde is 10-15:1;
preferably, the molar ratio of phosphorus oxychloride to parahydroxyben-zaldehyde is 1:3-4.
4. The method for preparing the hydroxyl-containing bi-valence phosphorus flame retardant according to claim 2, wherein: the temperature of the phosphorus oxychloride is-2 to 5 ℃, preferably 0 ℃.
5. The method for preparing the hydroxyl-containing bi-valence phosphorus flame retardant according to claim 2, wherein: the method for removing the solvent by evaporation is rotary evaporation.
6. The method for preparing the hydroxyl-containing bi-valence phosphorus flame retardant according to claim 2, wherein: the solvent added in the second reaction is selected from acetonitrile, dioxane, dimethylformamide or toluene;
preferably, in the second reaction, the molar ratio of intermediate I to DOPO is preferably 1:3 to 3.2;
it is further preferred that the molar ratio of intermediate I to DOPO is 1:3.
7. The method for preparing the hydroxyl-containing bi-valence phosphorus flame retardant according to claim 2, wherein: the method for purifying the solid comprises the following steps: dissolving the obtained solid with a solvent, then recrystallizing, filtering, washing and drying to obtain the pure flame retardant;
preferably, the solid-washed solvent is one or a combination of methanol, ethanol, methylene chloride, chloroform or dioxane;
preferably, the solvent used for the washing is ethanol.
8. A flame retardant modified epoxy resin, characterized in that: the coating comprises the following components in parts by mass: 73-78 parts of epoxy resin, 18-21 parts of curing agent and 1-9 parts of flame retardant.
9. The method for preparing the flame-retardant modified epoxy resin according to claim 8, which is characterized in that: the method comprises the following steps:
weighing epoxy resin, curing agent and flame retardant in proportion;
adding a flame retardant into epoxy resin at 100-115 ℃, uniformly mixing, vacuumizing to remove bubbles, and obtaining a first-grade mixture;
and adding the curing agent into the primary mixture, and uniformly mixing to obtain the secondary mixture.
10. The method for preparing the flame-retardant modified epoxy resin according to claim 9, wherein: the method also comprises the step of injecting the secondary mixture into a mold to prepare a target component by heating and curing;
preferably, the method of heat curing is as follows: heating and curing for 1-3h at 80-100 ℃, and then curing for 4-8h at 140-150 ℃.
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