Cyclophosphazene reactive flame retardant containing benzocyclobutene group, and preparation method therefor and use thereof

Abstract

Provided are a cyclophosphazene reactive flame retardant containing a benzocyclobutene group, and a preparation method therefor and the use thereof. In the molecular structural formula of the provided cyclophosphazene reactive flame retardant containing a benzocyclobutene group, at least one benzocyclobutene group is comprised on the phosphazene ring. The provided preparation method for the cyclophosphazene reactive flame retardant containing a benzocyclobutene group comprises: reacting a hydroxyl compound at least containing a hydroxyl BCB derivative with a halogenated cyclophosphazene under the action of an acid-binding agent, and purifying the product, so as to obtain a cyclophosphazene reactive flame retardant containing a benzocyclobutene group. Provided is a resin composition, to which the cyclophosphazene reactive flame retardant containing a benzocyclobutene group is applied; and in addition to the cyclophosphazene reactive flame retardant containing a benzocyclobutene group, the resin composition comprises at least one of an unsaturated monomer, an unsaturated resin, a benzocyclobutene monomer and a benzocyclobutene resin, which are polymerized under certain conditions so as to form a bulk flame retardant material. In the flame retardant material, nitrogen and phosphorus are synergistically flame retardant. The flame retardant material does not contain a polar group, has a low DK and Df, and has a high Tg, such that the flame retardant material is applied to a high-frequency and high-speed copper-clad laminate material.

Description

A reactive flame retardant containing benzocyclobutene groups, its preparation method and application

[0001] This application claims priority to Chinese Patent Application No. CN2024116375415, entitled “A reactive flame retardant containing a benzocyclobutene group cyclotriphosphazene and its preparation method and application thereof”, all contents of which are incorporated herein by reference. Technical Field

[0002] This invention relates to the field of flame retardants, and particularly to a reactive flame retardant containing benzocyclobutene groups and cyclophosphonitriles, its preparation method, and its application. Background Technology

[0003] With increasing awareness of environmental protection and human health, research on novel, highly efficient, low-toxicity, halogen-free, and environmentally friendly flame retardants has become a hot topic. Compared to additive flame retardants, which suffer from poor dispersibility, large addition amounts, and impact on the mechanical properties of the matrix, reactive flame retardants are uniformly dispersed in materials, have low loading amounts, no intermolecular rejection, and have minimal impact on the mechanical properties of materials. In particular, reactive flame retardants containing multiple flame-retardant elements in the same molecule for synergistic flame retardancy have advantages such as high flame-retardant efficiency and good charring performance, and have significant market demand. With the development of 5G technology, copper-clad laminate materials used in high-frequency and high-speed substrates are constantly evolving. Based on the high-frequency application conditions and the processing and assembly requirements of PCBs, they need to possess multiple performance characteristics. Among the main performance requirements, reducing the dielectric loss (Dk, Df) of high-frequency signals is the most important.

[0004] Currently, mainstream reactive flame retardants contain hydroxyl groups as reactive groups. The high polarity of hydroxyl groups makes them unsuitable for use in materials with low dielectric properties. For example, CN109467574A discloses a novel vanillin-based reactive flame retardant with hydroxyl groups in its structure. CN105175777A discloses a phosphorus-nitrogen synergistic reactive flame retardant for polyurethane, which also contains hydroxyl groups in its structure. These reactive flame retardants cannot meet the dielectric performance requirements of high-performance PCB boards, and hexaphenoxycyclotriphosphazene can only be used as an additive flame retardant.

[0005] Benzocyclobutene (BCB) is an excellent low-dielectric material, but it is a low-boiling-point volatile liquid and cannot be directly used in high-frequency and high-speed printed circuit boards (PCBs). The derivatization of benzocyclobutene to prepare reactive flame retardants has good application prospects. Summary of the Invention

[0006] In view of this, the purpose of this invention is to provide a reactive flame retardant containing benzocyclobutene cyclophosphonitrile, its preparation method, and its application. This reactive flame retardant has low DK and Df values ​​and high Tg. As a reactive flame retardant, it undergoes a Diels-Alder addition reaction with unsaturated olefin monomers, unsaturated resins, etc., to form a bulk flame retardant material. This overcomes the shortcomings of using additive flame retardants in the prior art and can be used in high-frequency, high-speed copper-clad laminate resin materials. Furthermore, the preparation method of this reactive flame retardant containing benzocyclobutene cyclophosphonitrile is suitable for large-scale industrial production.

[0007] To achieve the objectives of this invention, the following technical solution is provided:

[0008] In a first aspect, the present invention provides a reactive flame retardant containing a benzocyclobutene group cyclophosphonitrile, the general molecular structure of which is shown in Formula I:

[0009] Formula I,

[0010] In Formula I, the substituents R1, R2, R3, R4, R5, R6, and R 2n+5 R 2n+6 It includes at least one benzocyclobutene group; n is selected from 0, 1, 2, 3, 4 or 5, where n represents the number of nitrogen-phosphorus double bonds that may be added to the phosphazene ring. The substituents R1, R2, R3, R4, R5, R6, R... 2n+5 R 2n+6 Each can also be independently selected from alkyl, alkenyl, and aryl groups.

[0011] Furthermore, the substituents R1, R2, R3, R4, R5, R6, R 2n+5 R 2n+6 In this formulation, the alkyl group has an integer number of carbon atoms between 1 and 30, preferably not exceeding 18; the alkenyl group has an integer number of carbon atoms between 2 and 30, preferably not exceeding 12; and the aryl group has an integer number of carbon atoms between 6 and 30.

[0012] Preferably, the alkyl group includes one of methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, dodecyl, hexadecyl, and octadecyl; the alkenyl group includes one of allyl, allyl, allenyl, allenyl, allenylhexyl, allenheptyl, allenyl, allenyl, decyl, and allenyldodecyl; and the aryl group includes one of alkyl-substituted or unsubstituted phenyl, benzyl, phenethyl, phenylpropyl, phenylbutyl, biphenyl, biphenylmethyl, biphenylethyl, biphenylvinyl, bistyryl, vinylphenyl, allylphenyl, vinylbenzyl, and allylbenzyl.

[0013] Furthermore, the structural formula of the benzocyclobutene group is shown in Formula II:

[0014] Formula II,

[0015] In Formula II, the linker R7 is selected from one of chemical single bond, alkylene, alkenylene, and arylene; the substituent R8 is selected from one of hydrogen, alkyl, alkenyl, and aryl; m is an integer from 1 to 100, representing the number of benzocyclobutenyl groups on the linker R7; preferably, m is an integer from 1 to 10; more preferably, m is 1, 2, 3, 4, or 5.

[0016] Preferably, in the linker R7, the number of carbon atoms of the alkylene group is an integer from 1 to 30; the number of carbon atoms of the alkenyl group is an integer from 2 to 30; the number of carbon atoms of the aryl group is an integer from 6 to 30; the number of carbon atoms of the alkyl group is an integer from 1 to 30; the number of carbon atoms of the alkenyl group is an integer from 2 to 30; and the number of carbon atoms of the aryl group is an integer from 6 to 30.

[0017] More preferably, in the linker R7, the alkylene group includes one of methylene, ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, decylene, cyclohexylene, cyclopentylene, and hexadecylene; the alkenyl group includes one of vinylene, propenylene, butenylene, pentenylene, hexenylene, heptenylene, octylene, and decenylene; and the aryl group includes one of phenylene, benzylene, styrene, biphenylene, bistyrene, and biphenylethylene, which are substituted or unsubstituted with a hydrocarbon group having 1-18 carbon atoms.

[0018] Preferably, in the substituent R8, the alkyl group has no more than 30 carbon atoms, preferably no more than 18; the alkenyl group has no more than 30 carbon atoms, preferably no more than 12; and the aryl group has no more than 30 carbon atoms, preferably no more than 12.

[0019] More preferably, in substituent R8, the alkyl group includes at least one selected from methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, octadecyl, and cyclobutyl which is cyclic with benzocyclobutene; the alkenyl group includes one selected from vinyl, propenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, decenyl, dodecenyl, styryl, vinylstyryl, and bistyryl; and the aryl group includes one selected from phenyl, methylphenyl, ethylphenyl, benzyl, biphenyl, biphenylmethyl, phenyl which is cyclic with benzocyclobutene, and benzocyclobutenyl which is cyclic with benzocyclobutene.

[0020] In a second aspect, the present invention provides a method for preparing a reactive flame retardant containing benzocyclobutene cyclophosphonitrile, used to prepare a reactive flame retardant containing benzocyclobutene cyclophosphonitrile provided in the first aspect of the present invention. The reaction steps include: in a dry atmosphere, a hydroxyl compound and a halocyclophosphonitrile are subjected to a substitution reaction in an organic solvent and under the action of an acid-binding agent to obtain the reactive flame retardant containing benzocyclobutene cyclophosphonitrile.

[0021] The hydroxyl compounds include alcohols and / or phenols and their alkali metal salts, and at least include hydroxyl BCB derivatives as shown in Formula III:

[0022] Formula III;

[0023] In Formula III, the linker R7 is selected from one of chemical single bond, alkylene, alkenylene, and aryl; the substituent R8 is selected from one of hydrogen, alkyl, alkenyl, and aryl; and m is an integer from 1 to 100.

[0024] The molecular structure of the halocyclophosphonitrile is shown in Formula IV:

[0025] Formula V,

[0026] In formula V, X is a halogen, and n is selected from 0, 1, 2, 3, 4 or 5.

[0027] Furthermore, the operation of the substitution reaction includes: adding an organic solvent, a hydroxyl compound, and an acid-binding agent to a reactor under a dry atmosphere, then adding halocyclophosphinitrogen dropwise; after the addition is complete, heating and maintaining the temperature for the reaction.

[0028] Preferably, the temperature at which the halocyclophosphonitrile is added is between room temperature and 60°C.

[0029] Furthermore, the reaction step also includes a separation and purification operation after the substitution reaction is completed, to obtain the purified reactive flame retardant containing benzocyclobutene groups in cyclophosphonitriles.

[0030] Preferably, the hydroxyl compound and the acid-binding agent are completely dissolved in an organic solvent before the halocyclophosphonitrile is added dropwise; or the process may further include a step of preparing an alkali metal salt from the alcohol or phenol in the hydroxyl compound.

[0031] Furthermore, in the halocyclophosphonitrile, the halogen is selected from at least one of chlorine, bromine, and iodine.

[0032] Preferably, the halocyclic phosphazene includes at least one of hexachlorocyclotriphosphazene, hexabromocyclotriphosphazene, hexaiodocyclotriphosphazene, octachlorocyclotetraphosphazene, octabromocyclotetraphosphazene, octaiodocyclotetraphosphazene, decachlorocyclopentaphosphazene, dodecachlorocyclohexaphosphazene, tetradecylchlorocycloheptaphosphazene, and hexadecylchlorocyclooctaphosphazene.

[0033] Furthermore, the drying atmosphere includes at least one of an inert gas atmosphere and a drying device externally equipped with a desiccant for drying reaction environment; the inert gas includes at least one of nitrogen, argon, and helium; and the desiccant includes anhydrous calcium chloride.

[0034] Furthermore, the molar ratio of the hydroxyl group in the hydroxyl compound to the halogen in the halocyclophosphamide is (1.0-1.2):1.0, and the number of moles of the hydroxyl group in the hydroxy BCB derivative is at least 1.0 times the number of moles of the halocyclophosphamide.

[0035] Furthermore, the hydroxyl compound also includes at least one of the following: fatty alcohols with no more than 30 carbon atoms, alkenyl alcohols with no more than 30 carbon atoms, phenols with no more than 30 carbon atoms, and aromatic alcohols with no more than 30 carbon atoms.

[0036] Preferably, the hydroxyl compound further includes at least one of the following: aliphatic alcohols with no more than 18 carbon atoms, alkenyl alcohols with no more than 12 carbon atoms, phenols with no more than 12 carbon atoms, and aromatic alcohols with no more than 12 carbon atoms.

[0037] More preferably, the hydroxyl compound further includes at least one of methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, dodecanol, hexadecyl alcohol, octadecanol, propenol, butenol, pentenol, hexenol, heptenol, octenol, nonenol, decenol, dodecenol, phenol, methylphenol, ethylphenol, benzyl alcohol, biphenol, biphenylmethanol, vinylphenol, allylphenol, vinyl benzyl alcohol, allyl benzyl alcohol, hydroquinone, phenethyl alcohol, phenylpropanol, phenylbutanol, ethylene glycol, butenyl glycol, cis-4-cyclopenten-1,3-diol, and pentaerythritol; and also includes at least one salt of the aforementioned compound in the form of sodium alkoxide, potassium alkoxide, sodium phenolate, and potassium phenolate.

[0038] Further, the organic solvent includes at least one of acetonitrile, chlorobenzene, tetrahydrofuran, DMF, DMI, DMSO, DMAC, NMP, toluene, and xylene; the volume ratio of the solvent to the mass ratio of the halocyclophosphamide is (2-20):1.

[0039] Further, the acid-binding agent is at least one selected from potassium carbonate, sodium carbonate, potassium acetate, triethylamine, diisopropylethylamine, N-ethyldicyclohexylamine, tetramethylguanidine (TMG), 1,4-diazabicyclo[2.2.2]octane (DABCO), potassium hydroxide, sodium hydroxide, cesium hydroxide, sodium hydride, sodium methoxide, and sodium tert-butoxide; the molar ratio of the acid-binding agent to the halogen in the halocyclophosphonitrile is (1.0-1.5):1.0; preferably, the molar ratio of the acid-binding agent to the halogen in the halocyclophosphonitrile is (1.0-1.15):1.0.

[0040] Furthermore, the temperature of the heat preservation reaction is 60℃-130℃; the heat preservation reaction time is 12-72h.

[0041] Further, one method for separating and purifying the product includes: cooling the reaction solution to room temperature, sequentially adding an alkaline solution and saturated brine to wash until neutral, separating the organic phase, and concentrating the organic phase to obtain the residue by silica gel column chromatography to obtain the reactive flame retardant containing benzocyclobutene groups and cyclophosphonitrile.

[0042] Preferably, the alkaline solution includes at least one of potassium carbonate solution, potassium bicarbonate solution, sodium carbonate solution, and sodium bicarbonate solution.

[0043] Thirdly, the present invention provides a resin composition comprising the reactive flame retardant containing benzocyclobutene groups as described in the first aspect of the present invention.

[0044] Furthermore, the resin composition further includes at least one of unsaturated olefins, unsaturated resins, benzocyclobutene monomers, and benzocyclobutene resins.

[0045] Fourthly, the present invention provides a prepreg prepared from the resin composition of the third aspect. A PCB board includes the prepreg and the material from which it is made.

[0046] The beneficial effects of this invention are:

[0047] (1) This invention provides a reactive flame retardant containing benzocyclobutene groups and cyclophosphonitriles. This reactive flame retardant has a high phosphorus content, exhibits synergistic nitrogen-phosphorus flame retardancy, and its molecule contains active benzocyclobutene groups that can undergo Diels-Alder addition reactions with unsaturated olefins, unsaturated resins, etc. The flame retardant does not migrate and its addition does not deteriorate the physical properties of the material. Furthermore, the reactive flame retardant of this invention also has good material compatibility and stable performance. Therefore, it has very good application development prospects.

[0048] (2) The present invention provides a reactive flame retardant containing benzocyclobutene group cyclophosphonitrile, which is copolymerized with monomers or resins containing unsaturated double bonds, benzocyclobutene monomers, benzocyclobutene resins, etc. to form a bulk flame retardant material. It has low DK, Df, and high Tg. When applied to high frequency and high speed copper clad laminate resin materials, it can meet the stringent requirements of reducing the dielectric loss of high frequency signals.

[0049] (3) The present invention provides a method for preparing a reactive flame retardant containing benzocyclobutene groups and cyclophosphonitriles. The process is simple, the conditions are mild, the raw materials are readily available, and it is suitable for large-scale industrial production. Attached Figure Description

[0050] Figure 1 is the HNMR spectrum of the reactive flame retardant containing benzocyclobutene group cyclophosphonitrile obtained in Example 1 of the present invention;

[0051] Figure 2 is the infrared spectrum of the reactive flame retardant containing benzocyclobutene groups obtained in Example 1 of the present invention.

[0052] Figure 3 is the DSC diagram of reactive flame retardants A and C containing benzocyclobutene groups obtained in Examples 1 and 3 of the present invention, respectively;

[0053] Figure 4 shows the Tg diagrams of reactive flame retardants A and C containing benzocyclobutene groups obtained in Examples 1 and 3 of the present invention, respectively. Detailed Implementation

[0054] The embodiments of the present invention will be described in detail below. The embodiments described below are implemented based on the technical solution of the present invention, and detailed implementation methods and specific operation processes are given. However, the protection scope of the present invention is not limited to the embodiments described below.

[0055] In a first aspect, the present invention provides a reactive flame retardant containing a benzocyclobutene group cyclophosphonitrile, the general molecular structure of which is shown in the following formula:

[0056] Formula I,

[0057] Among them, the substituents R1, R2, R3, R4, R5, R6, and R 2n+5 R 2n+6 It includes at least one benzocyclobutene group; n is selected from 0, 1, 2, 3, 4, or 5, where n represents the number of additional nitrogen-phosphorus double bonds that may be added to the phosphazene ring. Substituents R1, R2, R3, R4, R5, R6, R 2n+5 R 2n+6 Each can also be independently selected from alkyl, alkenyl, and aryl groups.

[0058] It should be noted that the benzocyclobutene group includes at least one benzocyclobutene group, and may contain multiple benzocyclobutene groups formed by BCB group substitution, and is not limited to containing only one benzocyclobutene group.

[0059] It should be noted that the substituents R1 and R2, R3 and R4, R5 and R6, and R... 2n+5 With R 2n+6 The substituent can be a relatively independent substituent, or it can be a substituent in which any two or more substituents are connected to each other to form a ring, and should not be limited to the independent substituents represented in the structural formula.

[0060] It should be noted that n represents the number of additional nitrogen-phosphorus double bonds that can be added to the phosphazene ring; as n takes the values ​​1, 2, 3, 4, and 5, 2, 4, 6, 8, and 10 substituents are added respectively, and the substituent R 2n+5 Specifically, it may be represented as R7, R9, R 11 R 13 R 15 ;R 2n+6 It may be specifically represented as R8, R 10 R 12 R 14 R 16 Specifically, when n=0, there is no substituent R. 2n+5 R 2n+6 This indicates that at least one benzocyclobutene group is included among the substituents R1, R2, R3, R4, R5, and R6; when n=1, the substituent R 2n+5 R 2n+6 The substituents R7 and R8, which are added to the nitrogen-phosphorus double bond and connected to oxygen, can be the same as or different from any one of the substituents R1, R2, R3, R4, R5, and R6; however, when n is 2, 3, 4, or 5, the substituent R... 2n+5 R 2n+6 This should be understood as the addition of 4, 6, 8, or 10 identical or non-identical substituents for each additional nitrogen-phosphorus double bond, including at least one of alkyl, alkenyl, aryl, or benzocyclobutene groups. It should not be simply interpreted as equivalent to the two substituents added when n=1, representing two identical substituents R. 2n+5 R 2n+6 .

[0061] It should be noted that the alkyl group includes straight-chain or branched alkyl groups and cycloalkyl groups; the alkenyl group includes straight-chain or branched alkenyl groups and alkenyl-substituted hydrocarbon groups; the aryl group includes alkyl-substituted aryl groups, aryl-substituted alkyl groups, aryl-substituted aryl groups, polyaryl groups, and alkyl-substituted polyaryl groups. Unless otherwise specified, each substituent includes any of the possible isomers.

[0062] It should be noted that substituent R8 represents at least one substituent on the ring of benzocyclobutenyl, and can also be a substituent that forms a ring with BCB group, and is not limited to the substituent represented in Formula II and Formula III.

[0063] By way of example, the present invention provides a reactive flame retardant containing a benzocyclobutene group cyclophosphonitrile, including but not limited to compounds represented by the following structural formula AR. The compounds shown below are merely typical compounds and are readily available from raw materials, but should not be limited to the scope of protection of the present invention:

[0064] (A) (B)

[0065] (C) (D)

[0066] (E) (F)

[0067] (G) (H)

[0068] (I) (J)

[0069] (K) (L)

[0070] (M) (N)

[0071] (O) (P)

[0072] (Q) (R) (S) (T)

[0073] (U).

[0074] In a second aspect, the present invention provides a method for preparing a reactive flame retardant containing a benzocyclobutene group cyclophosphonitrile, used to prepare the reactive flame retardant containing a benzocyclobutene group cyclophosphonitrile described in the first aspect of the present invention, the reaction steps including:

[0075] In a dry atmosphere, an organic solvent, a hydroxyl compound, and an acid-binding agent are added to a reactor. Halogenated cyclophosphinitrogen is then added dropwise at an appropriate temperature. After the addition is complete, the temperature is raised and maintained for reaction. The mixture is then separated and purified to obtain the purified reactive flame retardant containing benzocyclobutene groups.

[0076] In this invention, to enhance the reactivity of the hydroxyl compound, the hydroxyl compound can also be prepared by further reacting the hydroxyl group with an alkali metal salt, etc., and then reacting it with a halocyclophosphinitron. Both the use of the hydroxyl compound as a raw material and the alkali metal salt of the hydroxyl compound fall within the scope of protection of the preparation method of the reactive flame retardant containing a benzocyclobutene group cyclophosphinitron described in this invention.

[0077] The following description is based on specific embodiments.

[0078] Example 1

[0079] In a reactor equipped with a stirrer, thermometer, reflux condenser, and drying device, 60 g of chlorobenzene, 22.3 g (0.185 mol) of 4-hydroxyBCB, and 18.8 g (0.186 mol) of triethylamine were added. The mixture was stirred, heated to 50 °C and kept at that temperature. A solution of 9.73 g (0.028 mol) of hexachlorocyclotriphosphazene in 10 g of chlorobenzene was added dropwise. After the addition was complete, the temperature was raised to 110 °C and the reaction was kept at that temperature for 24 h. The mixture was then cooled to room temperature. The reaction solution was washed successively with sodium carbonate solution and saturated brine. The organic phase was separated and washed until neutral. The organic phase was then concentrated. The residue was subjected to silica gel column chromatography. The chromatographic solution was then concentrated and dried to obtain 21.4 g of solid, with a yield of 90.0%. This solid is the reactive flame retardant containing benzocyclobutene groups, and its molecular structure is shown in formula (A).

[0080] The ¹H NMR spectrum of the product of this embodiment is shown in Figure 1, with data as follows: δ 2.93-3.11 (d, 24H), 6.75 (s, 6H), 6.79-6.82 (dd, 6H), 6.87-6.93 (d, 6H). The infrared spectrum of the product of this embodiment is shown in Figure 3. Analysis of the spectra and data confirms the molecular structure of compound A.

[0081] Example 2

[0082] In a reactor equipped with a stirrer, thermometer, reflux condenser, and drying device, 110g of toluene as solvent, 22.3g (0.185mol) of 3-hydroxyBCB, and 10.4g (0.186mol) of potassium hydroxide were added. The mixture was heated to reflux with toluene, and water was removed using a water separator. After reacting for 2 hours, the temperature was lowered to 40°C under a nitrogen atmosphere and maintained. A solution of 9.73g (0.028mol) of hexachlorocyclotriphosphazene in 10g of toluene was added dropwise. After the addition was complete, the temperature was raised to reflux with toluene and the reaction was maintained for 15 hours. The mixture was then cooled to room temperature, and the reaction solution was washed successively with sodium carbonate solution and saturated brine. The organic phase was separated and washed until neutral, then concentrated. The residue was subjected to silica gel column chromatography, and the chromatographic solution was further concentrated and dried to obtain 16.2g of a light yellow solid with a yield of approximately 68%, which is the reactive flame retardant containing benzocyclobutene groups of cyclophosphazene, with the molecular structure shown in formula (B).

[0083] The HNMR data of the product in this embodiment are: δ 3.01-3.13 (d, 24H), 7.10-7.13 (d, 6H), 7.16-7.19 (dd, 6H), 7.25-7.29 (m, 6H).

[0084] Example 3

[0085] In a reactor equipped with a stirrer, thermometer, reflux condenser, and drying device, 100g of tetrahydrofuran as solvent, 10.55g (0.088mol) of 4-hydroxyBCB, 11.81g (0.088mol) of o-allylphenol, and 18.8g (0.186mol) of triethylamine were added. The temperature was raised to 45℃ and maintained. A solution of 9.73g (0.028mol) of hexachlorocyclotriphosphazene in 15g of tetrahydrofuran was added dropwise. After the addition was complete, the temperature was raised to reflux and maintained for 72h. The mixture was then cooled to room temperature, and the insoluble matter was filtered off. The filtrate was washed successively with sodium carbonate solution and saturated brine. The organic phase was separated and washed until neutral, then concentrated. The residue was subjected to silica gel column chromatography. The chromatogram was then concentrated and dried to obtain 19.45g of a light yellow solid, with a yield of 78%, which is the reactive flame retardant containing benzocyclobutene groups of cyclophosphazene. The molecular structure of the flame retardant is shown in Formula C.

[0086] The HNMR data of the product in this embodiment are: δ 2.92-3.16 (d, 12H), 3.25 (s, 6H), 4.82-4.95 (dd, 3H), 5.92-6.12 (m, 6H), 6.85 (s, 3H), 6.91-7.03 (m, 6H), 7.16-7.25 (m, 12H).

[0087] Example 4

[0088] In a reactor equipped with a stirrer, thermometer, reflux condenser, and drying device, 60 g of chlorobenzene as solvent, 10.55 g (0.088 mol) of 4-hydroxyBCB, and 18.8 g (0.186 mol) of triethylamine were added. The temperature was raised to 50 °C and maintained. Then, 9.73 g (0.028 mol) of hexachlorocyclotriphosphazene (dissolved in 10 g of solvent) was added dropwise. After the addition was complete, the temperature was raised to reflux and the reaction was maintained for 12 h. Then, a solution of 9.52 g (0.088 mol) of o-methylphenol in 15 g of chlorobenzene was added dropwise, and the reaction was maintained for another 12 h. After the reaction was completed, the mixture was cooled to room temperature. The reaction solution was washed successively with sodium carbonate solution and brine. The organic phase was separated and washed until neutral, then concentrated. The residue was subjected to silica gel column chromatography. The chromatographic solution was then concentrated and dried to obtain 19.35 g of solid, with a yield of 85%, which is the reactive flame retardant containing benzocyclobutene groups. The molecular structure of the flame retardant is shown in Formula D.

[0089] The HNMR data of the product in this embodiment are: δ 2.19 (s, 9H), 2.91-3.17 (d, 12H), 6.85 (s, 3H), 6.96-7.13 (m, 6H), 7.19-7.28 (m, 12H).

[0090] Example 5

[0091] In a reactor equipped with a stirrer, thermometer, reflux condenser, and drying device, 60g of chlorobenzene as solvent, 10.81g (0.09mol) of 4-hydroxyBCB, and 18.8g (0.186mol) of triethylamine were added. The temperature was raised to 50℃ and maintained. 9.73g (0.028mol) of a 15g chlorobenzene solution of hexachlorocyclotriphosphazene was added dropwise. After the addition was complete, the temperature was raised to reflux and the reaction was maintained for 10h. Then, a 15g chlorobenzene solution of 10.81g (0.09mol) of p-hydroxystyrene was added dropwise, and the reaction was maintained for another 10h. After the reaction was completed, the mixture was cooled to room temperature. The reaction solution was washed successively with sodium carbonate solution and brine. The organic phase was separated and washed until neutral, then concentrated. The residue was subjected to silica gel column chromatography. The chromatographic solution was concentrated and dried to obtain 19.5g of solid, with a yield of 82%, which is the reactive flame retardant containing benzocyclobutene groups of cyclophosphazene. The molecular structure of the flame retardant is shown in Formula E.

[0092] The HNMR data of the product in this embodiment are: δ 2.90-3.14 (d, 12H), 5.38 (d, 3H), 5.96-6.08 (m, 6H), 6.85 (s, 3H), 6.91-7.03 (m, 6H), 7.16-7.25 (m, 12H).

[0093] Example 6

[0094] In a reactor equipped with a stirrer, thermometer, reflux condenser, and drying device, 60g of chlorobenzene as solvent, 6.97g (0.058mol) of 4-hydroxyBCB, and 24.9g (0.18mol) of potassium carbonate were added. The temperature was raised to 50℃ and maintained. A solution of 9.73g (0.028mol) of hexachlorocyclotriphosphazene in 15g of chlorobenzene was added dropwise. After the addition was complete, the temperature was raised to reflux and the reaction was maintained for 10h. Then, a solution of 11.19g (0.12mol) of phenol in 15g of chlorobenzene was added dropwise, and the reaction was maintained for another 10h. After the reaction was completed, the mixture was cooled to room temperature. The reaction solution was washed successively with sodium carbonate solution and saturated brine. The organic phase was separated and washed until neutral, then concentrated. The residue was subjected to silica gel column chromatography. The chromatographic solution was then concentrated and dried to obtain 16.3g of solid, with a yield of 78%, which is the reactive flame retardant containing benzocyclobutene groups of cyclophosphazene. The molecular structure of the flame retardant is shown in Formula F.

[0095] Example 7

[0096] In a reactor equipped with a stirrer, thermometer, reflux condenser, and drying device, 100g of tetrahydrofuran as solvent, 10.55g (0.088mol) of 4-hydroxyBCB, and 24.8g (0.18mol) of potassium carbonate were added. The temperature was raised to 50℃ and maintained. A solution of 9.73g (0.028mol) of hexachlorocyclotriphosphazene dissolved in 15g of tetrahydrofuran was then added dropwise. After the addition was complete, the temperature was raised to 65℃ and the reaction was maintained for 10 hours. Then, 6.93g (0.058mol) of... Hydroxystyrene was dissolved in a solution of 15 g tetrahydrofuran, and the reaction was continued at this temperature for 10 h. Then, 2.82 g (0.03 mol) of phenol dissolved in a solution of 15 g tetrahydrofuran was added dropwise, and the reaction was continued at this temperature for 40 h. After the reaction was completed, the mixture was cooled to room temperature, and the reaction solution was washed successively with sodium carbonate solution and saturated brine. The organic phase was separated and washed until neutral, then concentrated. The residue was subjected to silica gel column chromatography, and the chromatographic solution was further concentrated and dried to obtain 17.3 g of solid, with a yield of 75%, which is the reactive flame retardant containing benzocyclobutene groups in cyclophosphonitrile. The molecular structure of the flame retardant is shown in Formula G.

[0097] Example 8

[0098] In a reactor equipped with a stirrer, thermometer, reflux condenser, and drying device, 100g of tetrahydrofuran as solvent, 3.6g (0.03mol) of 4-hydroxyBCB, and 24.8g (0.18mol) of potassium carbonate were added. The temperature was raised to 50℃ and maintained. Then, a solution of 9.73g (0.028mol) of hexachlorocyclotriphosphazene dissolved in 15g of tetrahydrofuran was added dropwise. After the addition was complete, the temperature was raised to 65℃ and the reaction was maintained for 10 hours. Finally, 8.3g (0.088mol) of phenol dissolved in 15g of tetrahydrofuran was added dropwise. The solution was prepared in tetrahydrofuran solvent, and the reaction was continued at this temperature for 10 hours. Then, 7.27 g (0.06 mol) of p-hydroxystyrene dissolved in 15 g of tetrahydrofuran solvent was added dropwise, and the reaction was continued at this temperature for 40 hours until the reaction was complete. After cooling to room temperature, the reaction solution was washed successively with sodium carbonate solution and saturated brine. The organic phase was separated and washed until neutral, then concentrated. The residue was subjected to silica gel column chromatography, and the chromatographic solution was further concentrated and dried to obtain 17.6 g of a yellow viscous liquid, with a yield of 81.5%, which is the reactive flame retardant containing benzocyclobutene groups in cyclophosphonitrile. The molecular structure of the flame retardant is shown in Formula H.

[0099] Example 9

[0100] In a reactor equipped with a stirrer, thermometer, reflux condenser, and drying device, 100g of tetrahydrofuran as solvent, 7.0g (0.058mol) of 4-hydroxyBCB, and 24.84g (0.18mol) of potassium carbonate were added. The temperature was raised to 50℃ and maintained. A solution of 9.73g (0.028mol) of hexachlorocyclotriphosphazene dissolved in 15g of tetrahydrofuran was then added dropwise. After the addition was complete, the temperature was raised to 65℃ and the reaction was maintained for 10 hours. Then, 9.54g (0.088mol) of p-methylphenol dissolved in... A solution of 15g tetrahydrofuran solvent was added, and the reaction was continued at the specified temperature for 10 hours. Then, 3.6g (0.03mol) of p-hydroxystyrene dissolved in 15g tetrahydrofuran solvent was added dropwise, and the reaction was continued at the specified temperature for 40 hours. After the reaction was completed, the mixture was cooled to room temperature. The reaction solution was washed successively with sodium carbonate solution and saturated brine. The organic phase was separated and washed until neutral, then concentrated. The residue was subjected to silica gel column chromatography. The chromatographic solution was then concentrated and dried to obtain 18.1g of solid, with a yield of 79.5%, which is the reactive flame retardant containing benzocyclobutene groups in cyclotriphosphazene. The molecular structure of the flame retardant is shown in Figure I.

[0101] Example 10

[0102] In a reactor equipped with a stirrer, thermometer, reflux condenser, and drying device, 100g of tetrahydrofuran as solvent, 6.72g (0.056mol) of 4-hydroxyBCB, and 24.8g (0.18mol) of potassium carbonate were added. The temperature was raised to 50℃ and maintained. Then, a solution of 9.73g (0.028mol) of hexachlorocyclotriphosphazene dissolved in 15g of tetrahydrofuran was added dropwise. After the addition was complete, the temperature was raised to 65℃ and the reaction was maintained for 20 minutes. Then, 12.1 g (0.112 mol) of p-methylphenol dissolved in 15 g of tetrahydrofuran solvent was added dropwise, and the reaction was continued at this temperature for 20 h. After the reaction was completed, the mixture was cooled to room temperature. The reaction solution was washed successively with sodium carbonate solution and saturated brine to separate the organic phase, which was then washed until neutral and concentrated. The residue was subjected to silica gel column chromatography, and the chromatographic solution was further concentrated and dried to obtain 17.5 g of solid, with a yield of 78%, which is the reactive flame retardant containing benzocyclobutene groups in cyclophosphonitrile. The molecular structure of the flame retardant is shown in Formula J.

[0103] Example 11

[0104] In a reactor equipped with a stirrer, thermometer, reflux condenser, and drying device, 100g of tetrahydrofuran as solvent, 17.66g (0.147mol) of 4-hydroxyBCB, and 24.8g (0.18mol) of potassium carbonate were added. The temperature was raised to 50℃ and maintained. A solution of 9.73g (0.028mol) of hexachlorocyclotriphosphazene dissolved in 15g of tetrahydrofuran was added dropwise. After the addition was complete, the temperature was raised to 65℃ and the reaction was maintained for 10h. Then, 2.88g (0.03mol) of phenol was added dropwise, and the reaction was maintained for another 10h. After the reaction was completed, the mixture was cooled to room temperature. The reaction solution was washed successively with sodium carbonate solution and saturated brine. The organic phase was separated and washed until neutral, then concentrated. The residue was subjected to silica gel column chromatography. The chromatographic solution was concentrated and dried to obtain 18.9g of a light yellow solid, with a yield of 82%, which is the reactive flame retardant containing benzocyclobutene groups. The molecular structure of the flame retardant is shown in formula K.

[0105] Example 12

[0106] In a reactor equipped with a stirrer, thermometer, reflux condenser, and drying device, 100g of tetrahydrofuran as solvent, 14.0g (0.116mol) of 4-hydroxyBCB, and 24.8g (0.18mol) of potassium carbonate were added. The temperature was raised to 50℃ and maintained. A solution of 9.73g (0.028mol) of hexachlorocyclotriphosphazene dissolved in 15g of tetrahydrofuran was added dropwise. After the addition was complete, the temperature was raised to 65℃ and the reaction was maintained for 20h. Then, 7.0g (0.058mol) of the solution was added dropwise. A solution of p-hydroxystyrene dissolved in 20g of tetrahydrofuran was continuously reacted at this temperature for 20h. After the reaction was completed, the mixture was cooled to room temperature, and the reaction solution was washed successively with sodium carbonate solution and saturated brine. The organic phase was separated and washed until neutral, then concentrated. The residue was subjected to silica gel column chromatography, and the chromatographic solution was further concentrated and dried to obtain 19.7g of solid, with a yield of 83%, which is the reactive flame retardant containing benzocyclobutene groups in cyclophosphonitrile. The molecular structure of the flame retardant is shown in Formula L.

[0107] Example 13

[0108] In a reactor equipped with a stirrer, thermometer, reflux condenser, and drying device, 100g of tetrahydrofuran as solvent, 14.26g (0.118mol) of 4-hydroxyBCB, and 18.2g (0.18mol) of triethylamine were added. The temperature was raised to 50℃ and maintained. 9.73g (0.028mol) of hexachlorocyclotriphosphazene dissolved in 15g of tetrahydrofuran was added dropwise. After the addition was complete, the temperature was raised to 65℃ and the reaction was maintained for 20h. Then, 6.6g (0.058mol) of potassium tert-butoxide was added, and the reaction was maintained for another 20h. After the reaction was completed, the mixture was cooled to room temperature. The reaction solution was washed successively with sodium carbonate solution and saturated brine. The organic phase was separated and washed until neutral, then concentrated. The residue was subjected to silica gel column chromatography. The chromatographic solution was then concentrated and dried to obtain 17.4g of a yellow viscous liquid, with a yield of 82%, which is the reactive flame retardant containing benzocyclobutene groups. The molecular structure of the flame retardant is shown in formula M.

[0109] Example 14

[0110] In a reactor equipped with a stirrer, thermometer, reflux condenser, and drying device, 100 g of tetrahydrofuran as solvent, 24.15 g (0.18 mol) of 4-hydroxymethyl BCB, and 19.2 g (0.19 mol) of triethylamine were added. The temperature was raised to 50 °C and maintained. Then, 9.73 g (0.028 mol) of hexachlorocyclotriphosphazene dissolved in 15 g of tetrahydrofuran was added dropwise. After the addition was complete, the temperature was raised to 65 °C and the reaction was maintained for 40 h. After the reaction was completed, the mixture was cooled to room temperature. The reaction solution was washed successively with sodium carbonate solution and saturated brine. The organic phase was separated and washed until neutral, then concentrated. The residue was subjected to silica gel column chromatography. The chromatographic solution was further concentrated and dried to obtain 23.4 g of a light yellow solid, with a yield of 78%, which is the reactive flame retardant containing benzocyclobutene groups. The molecular structure of the flame retardant is shown in Formula N.

[0111] Example 15

[0112] Under nitrogen protection, in a reactor equipped with a stirrer, thermometer, reflux condenser, and drying device, 100g of tetrahydrofuran as solvent, 15.78g (0.12mol) of 4-hydroxymethyl BCB, and 19.2g (0.19mol) of triethylamine were added. The temperature was raised to 50℃ and maintained. Then, 9.73g (0.028mol) of hexachlorocyclotriphosphazene dissolved in 15g of tetrahydrofuran solvent was added dropwise. After the addition was complete, the temperature was raised to 65℃ and the reaction was maintained for 20h. Then, 6.36g (0.058mol) of benzyl alcohol was added, and the reaction was maintained for another 20h. After the reaction was completed, the mixture was cooled to room temperature. The reaction solution was washed successively with sodium carbonate solution and saturated brine. The organic phase was separated and washed until neutral, then concentrated. The residue was subjected to silica gel column chromatography. The chromatographic solution was then concentrated and dried to obtain 18.5g of light yellow solid, with a yield of 75%, which is the reactive flame retardant containing benzocyclobutene groups. The molecular structure of the flame retardant is shown in Formula O.

[0113] Example 16

[0114] Under nitrogen protection, in a reactor equipped with a stirrer, thermometer, reflux condenser, and connected to a dryer, 100g of tetrahydrofuran as solvent, 15.78g (0.12mol) of 4-hydroxymethyl BCB, and 19.2g (0.19mol) of triethylamine were added. The temperature was raised to 50℃ and maintained. Then, 9.73g (0.028mol) of hexachlorocyclotriphosphazene dissolved in 15g of tetrahydrofuran solvent was added dropwise. After the addition was complete, the temperature was raised to 60℃. The reaction was carried out at 5℃ for 20 hours, followed by the addition of 6.96 g (0.058 mol) of p-hydroxystyrene, and the reaction was continued for another 20 hours. After the reaction was completed, the mixture was cooled to room temperature. The reaction solution was washed successively with sodium carbonate solution and saturated brine to separate the organic phase, which was then washed until neutral and concentrated. The residue was subjected to silica gel column chromatography, and the chromatographic solution was further concentrated and dried to obtain 19.7 g of a light yellow solid, with a yield of 78%, which is the reactive flame retardant containing benzocyclobutene groups. The molecular structure of the flame retardant is shown in Formula P.

[0115] Example 17

[0116] Under nitrogen protection, in a reactor equipped with a stirrer, thermometer, reflux condenser, and connected to a dryer, 100g of tetrahydrofuran as solvent, 3.30g (0.03mol) of catechol, and 19.2g (0.19mol) of triethylamine were added. The temperature was raised to 50℃ and maintained. Then, 9.73g (0.028mol) of hexachlorocyclotriphosphazene dissolved in 15g of tetrahydrofuran solvent was added dropwise. After the addition was complete, the temperature was raised to 65℃ and maintained. The reaction was carried out at a warm temperature for 20 hours, followed by the addition of 15.78 g (0.12 mol) of 4-hydroxymethyl BCB, and the reaction was continued at this temperature for another 20 hours. After the reaction was completed, the mixture was cooled to room temperature. The reaction solution was washed successively with sodium carbonate solution and saturated brine, the organic phase was separated and washed until neutral, then concentrated. The residue was subjected to silica gel column chromatography, and the chromatographic solution was further concentrated and dried to obtain 16.7 g of a light yellow solid, with a yield of 77%, which is the reactive flame retardant containing benzocyclobutene groups (cyclophosphonitrile). The molecular structure of the flame retardant is shown in Formula Q.

[0117] Example 18

[0118] Under nitrogen protection, in a reactor equipped with a stirrer, thermometer, reflux condenser, and a dryer, 100g of tetrahydrofuran as solvent, 3.30g (0.03mol) of catechol, and 19.2g (0.19mol) of triethylamine were added. The temperature was raised to 50℃ and maintained. Then, 9.73g (0.028mol) of hexachlorocyclotriphosphazene dissolved in 15g of tetrahydrofuran was added dropwise. After the addition was complete, the temperature was raised to 65℃ and the reaction was maintained for 20h. Then, 14.42g (0.12mol) of 4-hydroxyBCB was added, and the reaction was maintained for another 30h. After the reaction was completed, the mixture was cooled to room temperature. The reaction solution was washed successively with sodium carbonate solution and saturated brine. The organic phase was separated and washed until neutral, then concentrated. The residue was subjected to silica gel column chromatography. The chromatographic solution was then concentrated and dried to obtain 15.3g of a light yellow solid, with a yield of 76%, which is the reactive flame retardant containing benzocyclobutene groups. The molecular structure of the flame retardant is shown in formula R.

[0119] Example 19

[0120] Under nitrogen protection, 28.0 g (0.23 mol) of 4-hydroxyBCB, 24.28 g (0.24 mol) of triethylamine, 120 g of chlorobenzene, and 12.98 g (0.028 mol) of octachlorocyclotetraphosphazene in a 20 g chlorobenzene solution were reacted under the same reaction conditions and post-treatment method as in Example 1 to prepare a reactive flame retardant containing benzocyclobutene groups, with a yield of 80%.

[0121] Example 20

[0122] Under a nitrogen atmosphere, 35.3 g (0.29 mol) of 4-hydroxyBCB, 30.3 g (0.3 mol) of triethylamine, 150 g of chlorobenzene, and 14.26 g (0.028 mol) of decachlorocyclopentaphosphazene in a 25 g chlorobenzene solution were reacted under the same reaction conditions and post-treatment method as in Example 1 to prepare a reactive flame retardant containing benzocyclobutene groups, with a yield of 78%.

[0123] Example 21

[0124] Under a nitrogen atmosphere, 19.46 g (0.028 mol) of a 35 g chlorobenzene solution of dodecylcyclohexanenitrile was reacted with 41.2 g (0.34 mol) of 4-hydroxymethyl BCB, 35.4 g (0.38 mol) of triethylamine, and 180 g of chlorobenzene, using the same reaction conditions and post-treatment method as in Example 1, to prepare a reactive flame retardant containing a benzocyclobutene group, with a yield of 81%.

[0125] Application Performance Examples

[0126] The reactive flame retardants containing benzocyclobutene groups and cyclophosphonitriles prepared in Examples 1-21 were heat-cured at 230-250℃ for 30 min-1 h to form cured films. The Tg results are shown in Table 1.

[0127] Phosphorus was quantitatively analyzed using the indirect method of phosphomolybdate colorimetric method. The results of phosphorus content testing of the reactive flame retardants containing benzocyclobutene groups prepared in Examples 1-21 using the UV-530 ultraviolet-visible spectrophotometer (Shimadzu, Japan) are shown in Table 1.

[0128] Furthermore, the reactive flame retardant containing benzocyclobutene groups prepared in Examples 1-21 was mixed with the benzocyclobutene resin containing olefin bonds prepared in our invention CN202211699345.1 at a mass ratio of 1:10, and the mixture was thermocured at 160-260°C to prepare a cured film. The dielectric constant Dk and dielectric loss tangent Df were tested at a frequency of 10 GHz, and the results are shown in Table 1.

[0129] Table 1. Performance test results of the products from the examples

[0130]

[0131] From the data in Table 1, the phosphorus content test results of the reactive flame retardants containing benzocyclobutene groups prepared in Examples 1-21 are consistent with the phosphorus content of the theoretical structure.

[0132] The DSC diagrams of the products from Examples 1 and 3 are shown in Figure 3:

[0133] As shown in DSC Figure 3, the exothermic peak of the benzocyclobutene four-membered ring is between 220-270℃, with a peak temperature of 250℃. A higher enthalpy indicates the presence of more four-membered rings in the unit compound. This cyclophosphonitrile compound containing a benzocyclobutene group, when heated to 220-270℃, can undergo Diels-Alder addition with monomers or resins containing unsaturated double bonds to form a bulk flame-retardant material. A partial structural diagram of the mechanism is shown below:

[0134] .

[0135] Figure 4 shows the Tg test results for the flame retardants in Examples 1 and 3, respectively.

[0136] To investigate the flame retardant effect of the flame retardant of the present invention, the reactive flame retardant containing benzocyclobutene groups and cyclophosphonitrile prepared in Examples 1-21 was added to unsaturated hydrocarbon resin at a mass ratio of 1:10. Oxygen index (LOI), vertical burning performance, and heat resistance were tested according to GB2406-93 and UL-94 standards. The results are shown in Table 2 below:

[0137] Table 2. Effect of reactive flame retardants containing benzocyclobutene groups (cyclophosphonitriles) on the flame retardant properties of hydrocarbon resins.

[0138]

[0139]

[0140] As can be seen from the table above, the reactive flame retardant containing benzocyclobutene groups synthesized using the present invention exhibits good flame retardancy in 100 parts of unsaturated hydrocarbon resin. When the amount added exceeds 16 parts, the oxygen index is significantly improved. Vertical burning tests show that its flame retardancy level can reach UL-94 V0, demonstrating highly efficient flame retardant performance.

[0141] Thirdly, the present invention provides a resin composition comprising at least the reactive flame retardant containing benzocyclobutene groups as described in the first aspect of the present invention.

[0142] Furthermore, the resin composition further includes one or more of unsaturated monomers, unsaturated resins, benzocyclobutene monomers, and benzocyclobutene resins. The unsaturated bonds in the unsaturated monomers and unsaturated resins can polymerize with the olefin bonds in the reactive flame retardant containing benzocyclobutene groups (cyclophosphonitrile) to form a cross-linked polymer under the action of an initiator; or, under high-temperature conditions, the unsaturated bonds in the unsaturated resins can ring-open polymerize with the cyclobutyl groups in the BCB groups of the reactive flame retardant containing benzocyclobutene groups to form a cross-linked polymer.

[0143] Furthermore, the resin composition further includes at least one of a thermal initiator, a crosslinking agent, and an inorganic filler.

[0144] Preferably, the resin composition comprises the following raw materials in parts by weight:

[0145] Unsaturated monomers and / or resins: 0-60 parts by weight;

[0146] Benzocyclobutene monomer and / or resin: 0-60 parts by weight;

[0147] The reactive flame retardant containing benzocyclobutene groups and cyclophosphonitriles: 5-40 parts by weight;

[0148] Thermal initiator: 0-10 parts by weight;

[0149] Crosslinking agent: 0-15 parts by weight;

[0150] Inorganic filler: 10-60 parts by weight.

[0151] The unsaturated monomers include at least one of styrene, allylbenzene, allylbenzene, divinylbenzene, butadiene, pentadiene, hexadiene, heptaadiene, octadiene, nonadiene, decadiene, bistyrene, vinylbiphenyl, divinylbiphenyl, and vinylbenzocyclobutene.

[0152] The unsaturated resin includes at least one of polybutadiene resin, polyisoprene resin, polybutadiene-styrene resin, polybutadiene-divinylbenzene resin, polyisoprene-styrene resin, polybutadiene-styrene resin, polybutadiene-styrene-divinylbenzene resin, polyisoprene-divinylbenzene resin, and polyisoprene-styrene-divinylbenzene resin.

[0153] The benzocyclobutene monomers include at least one benzocyclobutene-substituted alkyl, alkenyl, aryl, silane, or silyl ether derivative; such as vinylbenzocyclobutene, mono- or bis-BCB-substituted alkyl, alkenyl, or aryl derivatives, and DVS-BCB, etc.

[0154] The benzocyclobutene resin includes polymers containing benzocyclobutene groups on their branches; it can be a polymer of alkenyl benzocyclobutene derivatives or a benzocyclobutene-modified polymer; for example, BCB resin obtained by polymerizing monomers such as vinylbenzocyclobutene, bisbenzocyclobutenylethylene, bisbenzocyclobutenyldecadiene, bisbenzocyclobutenyldivinylbenzene, and DVS-BCB; it also includes benzocyclobutene-modified polybutadiene resin, polyisoprene resin, polybutadiene-styrene resin, polybutadiene-divinylbenzene resin, polydivinylbenzene resin, polyisoprene-styrene resin, polybutadiene-styrene-divinylbenzene resin, polyisoprene-divinylbenzene resin, and polyisoprene-styrene-divinylbenzene resin, etc. For example, the benzocyclobutene resin containing alkenyl bonds prepared by invention patent CN202211699345.1.

[0155] Fourthly, the present invention provides a prepreg, which is prepared from the resin composition of the third aspect. Specifically, a sol solution with a xylene solid content of 50%-75% is prepared according to the weight parts of each component in the resin composition. Under a nitrogen atmosphere, the sol solution is injected into an impregnation tank, and then a glass fiber cloth (e.g., L-glass fiber fabric of specification 2116) is immersed in the impregnation tank to allow the resin composition to adhere to the glass fiber cloth. The mixture is then heated at 150°C to 260°C to a semi-cured state to obtain the prepreg. A PCB board includes the prepreg and the material from which it is made.

[0156] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A reactive flame retardant containing a benzocyclobutene group cyclophosphonitrile, characterized in that, The general molecular structure is shown in Formula I: Formula I, In Formula I, the substituents R1, R2, R3, R4, R5, R6, and R 2n+5 R 2n+6 It includes at least one benzocyclobutene group; n is selected from 0, 1, 2, 3, 4 or 5.

2. The reactive flame retardant containing benzocyclobutene groups of cyclophosphonitrile according to claim 1, characterized in that, The substituents R1, R2, R3, R4, R5, R6, R 2n+5 R 2n+6 Each can also be independently selected from alkyl, alkenyl, and aryl groups.

3. The reactive flame retardant containing benzocyclobutene groups of cyclophosphonitrile according to claim 2, characterized in that, The alkyl group has no more than 30 carbon atoms; preferably, the alkyl group has no more than 18 carbon atoms; the alkenyl group has no more than 30 carbon atoms; preferably, the alkenyl group has no more than 12 carbon atoms; and the aryl group has no more than 30 carbon atoms.

4. The reactive flame retardant containing benzocyclobutene groups of cyclophosphonitrile according to claim 1, characterized in that, The structural formula of the benzocyclobutene group is shown in Formula II: Formula II, In Formula II, the linker R7 is selected from one of chemical single bond, alkylene, alkenylene, and arylene; the substituent R8 is selected from one of hydrogen, alkyl, alkenyl, and aryl; and m is an integer from 1 to 100.

5. A reactive flame retardant containing a benzocyclobutene group cyclophosphonitrile according to claim 4, characterized in that, In the linker R7, the number of carbon atoms in the alkylene group does not exceed 30, preferably not more than 18; the number of carbon atoms in the alkenylene group does not exceed 30, preferably not more than 12; and the number of carbon atoms in the arylene group does not exceed 30, preferably not more than 12. In the substituent R8, the alkyl group has no more than 30 carbon atoms, preferably no more than 18; the alkenyl group has no more than 30 carbon atoms, preferably no more than 12; and the aryl group has no more than 30 carbon atoms, preferably no more than 12. The m is an integer from 1 to 10; more preferably, m is 1, 2, 3, 4 or 5.

6. A method for preparing a reactive flame retardant containing a benzocyclobutene group as described in any one of claims 1-5, characterized in that, The reaction steps include: under a dry atmosphere, a hydroxyl compound is reacted with a halocyclophosphonitrile in an organic solvent and with the help of an acid-binding agent to obtain the reactive flame retardant containing the benzocyclobutene group cyclophosphonitrile; The hydroxyl compounds include alcohols and / or phenols and their alkali metal salts, and at least include hydroxyl BCB derivatives as shown in Formula III: Formula III; In Formula III, the linker R7 is selected from one of a single chemical bond, alkylene, alkenylene, or aryl; the substituent R8 is selected from one of hydrogen, alkyl, alkenyl, or aryl; and m is an integer from 1 to 100. The molecular structure of the halocyclophosphonitrile is shown in Formula V: Formula V; In formula V, X is a halogen; n is selected from 0, 1, 2, 3, 4 or 5.

7. The method for preparing a reactive flame retardant containing a benzocyclobutene group cyclophosphonitrile according to claim 6, characterized in that, The molar ratio of the hydroxyl group in the hydroxyl compound to the halogen in the halocyclophosphamide is (1.0-1.2):1.0, and the molar number of hydroxyl groups in the hydroxy BCB derivative is at least 1.0 times the molar number of the halocyclophosphamide; and / or, The hydroxyl compound further includes at least one of the following: aliphatic alcohols with no more than 30 carbon atoms, alkenyl alcohols with no more than 30 carbon atoms, phenols with no more than 30 carbon atoms, and aromatic alcohols with no more than 30 carbon atoms; preferably, the hydroxyl compound further includes at least one of the following: aliphatic alcohols with no more than 18 carbon atoms, alkenyl alcohols with no more than 12 carbon atoms, phenols with no more than 12 carbon atoms, and aromatic alcohols with no more than 12 carbon atoms; and / or, The reaction steps also include a separation and purification operation after the substitution reaction is completed, to obtain the purified reactive flame retardant containing benzocyclobutene groups and cyclophosphonitriles.

8. A resin composition, characterized in that, The resin composition comprises the reactive flame retardant containing benzocyclobutene groups of cyclophosphonitriles as described in any one of claims 1-5.

9. A resin composition according to claim 8, characterized in that, The resin composition further includes at least one of unsaturated resin, benzocyclobutene monomer, and benzocyclobutene resin.

10. A semi-cured sheet, characterized in that, It is prepared by thermosetting the resin composition according to claim 8; a PCB board includes the prepreg and the material obtained therefrom.

Images