Allylated maleimide phenolic resin and preparation method thereof

Abstract

The present application discloses an allylated maleimide phenolic resin, the structural formula of which is shown in the following formula (1), wherein n is selected from an integer of 60 to 80. A preparation method of the above-mentioned allylated maleimide phenolic resin is also disclosed, comprising: adding p-aminophenol, maleic anhydride and an organic solvent to a reactor to carry out an acylation reaction; adding a salt-forming agent to the product of the acylation reaction to carry out a salt-forming reaction; adding an allyl halide to the product of the salt-forming reaction to carry out an etherification reaction; adding a catalyst I to the product of the etherification reaction, and then dripping a formaldehyde solution to carry out a polycondensation reaction; adding a catalyst II to the product of the polycondensation reaction to carry out an imidization reaction to obtain an allylated maleimide phenolic resin. The resin prepared in the present application has excellent heat resistance, and can further improve the residual carbon rate, intrinsic flame retardancy and heat resistance after being fully cured at high temperature. At the same time, the process of the present application is simple, the raw material cost is low, and it is conducive to industrial production. Formula (I).

Description

Technical Field

[0001] The present application relates to the field of high temperature resistant polymers, and in particular to an allylated maleimide phenolic resin and a preparation method thereof. Background Art

[0002] Polyimide is a type of polymer material with excellent comprehensive properties. It has particularly excellent heat resistance, low temperature resistance, electrical properties and mechanical properties. It is widely used in electronic microelectronics, printed circuit boards, wires and cables, motor main insulation, shipbuilding, aerospace, laser, optoelectronics and other high-tech fields.

[0003] Phenolic resin (PF) is a special resin obtained by polymerizing formaldehyde and phenolic compounds under acidic or alkaline conditions. The cured product has good heat resistance and mechanical properties and is widely used in many fields such as automobiles, electronics, electrical, transportation, and military. However, PF has disadvantages such as high brittleness, high water absorption, small molecules produced upon curing, and easy high-temperature oxidative cracking of methylene groups.

[0004] When thermoplastic phenolic resin is cured, a curing agent such as hexamethylenetetramine needs to be added. During the curing, small molecules such as ammonia and water are easily released, resulting in the formation of many microporous structures inside the material. Adopting the addition curing mechanism to cure phenolic resin is an important direction to improve the curing structure of thermoplastic phenolic resin. For example, a group with a double bond is introduced into the resin molecule for addition curing without adding a curing agent.

[0005] There have been reports on addition-cured phenolic resins. CP Reghunadhan Nair* et al. discussed addition-cured phenolic resins in detail in Advances in addition-cure phenolic resins[J], Prog. Polym. Sci. 29 (2004) 401-498, including allyl and maleimide functionalized phenolic resins, epoxy phenolic resins, polybenzoxazine, bis-oxazoline phenolic resins, acetylene functionalized phenolic resins, phenolic triazine resins and propargyl ether phenolic resins.

[0006] Zhou Dapeng et al. introduced N-phenylmaleimide into the molecule of thermoplastic phenolic resin in Synthesis and Structural Properties of N-phenylmaleimide-modified Phenolic Resin [J]. Journal of Chemical Industry, 2005 (10): 1987-1992, which further improved the heat resistance of the resin. During curing, the resin undergoes self-crosslinking curing by double bond addition, thus avoiding the use of curing agent.

[0007] Guo Danyu et al. disclosed a method for preparing N-phenylmaleimide (N-PMI) modified phenolic resin microspheres in Preparation and Characterization of N-PMI Modified Phenolic Resin Microspheres [J]. Polymer Materials Science and Engineering, 2011, 27(05): 160-162. The method adopts suspension polymerization to synthesize N-PMI modified phenolic resin with formaldehyde, phenol and (N-PMI) as raw materials.

[0008] Japanese patent publication JP2005314499A discloses an allyl ether or allyl modified biphenyl aralkyl phenolic novolac resin and a preparation method thereof, wherein the allyl ether modified biphenyl aralkyl phenolic novolac resin is obtained by etherification reaction with biphenyl aralkyl phenolic novolac resin, alkaline catalyst and allyl chloride.

[0009] Chinese patent application CN200610011779.2 discloses a polysiloxane toughened allyl-based linear phenolic / bismaleimide resin, the preparation method of which comprises: uniformly mixing a polysiloxane allyl-based linear phenolic resin solution and reacting it under the action of a metal catalyst to obtain a polysiloxane toughened allyl-based linear phenolic resin, and then adding a bismaleimide monomer and refluxing to remove the solvent to obtain a polysiloxane toughened allyl-based linear phenolic / bismaleimide resin.

[0010] Chinese patent application CN202010143780.0 discloses a maleimide-modified 4-tert-butylphenol formaldehyde resin and a synthesis method thereof, wherein 4-tert-butylphenol, 4-maleimidophenol, formaldehyde and a catalyst are put into a reaction container, a condensation reaction is carried out at 80-100°C, and after the organic phase is extracted, a polycondensation reaction is carried out at 160-190°C.

[0011] He Xiancheng et al. synthesized and characterized allyl phenolic resin in Preparation and Properties of Allyl Phenolic Modified Bismaleimide Resin [J]. Thermosetting Resins, 2013, 28 (03): 19-23, using allyl phenolic modified bismaleimide resin.

[0012] Zhang Dayong et al. prepared allyl phenolic resin by reacting allyl chloride with thermoplastic phenolic resin and then added bismaleimide resin to copolymerize with allyl phenolic resin to prepare allyl phenolic-bismaleimide resin, and then added toughening agent to prepare high temperature resistant adhesive.

[0013] Chinese patent authorization text CN109705799B discloses a YASI epoxy organic imide silica gel and a preparation method thereof, which is composed of 2, 2-bis(3-amino-4-hydroxyphenyl)propane BAHPP, double-terminated aminopropyl polydimethylsiloxane YASI, N, N, N', N'-tetraglycidyl-4, 4'-diaminodiphenylmethane TGDDM, a reaction product of an aromatic diamine, an aromatic dibasic anhydride and 3-aminopropyltrialkoxysilane, and an organic solvent.

[0014] Chinese patent authorization text CN109722212B discloses an imide epoxy silicone rubber and a preparation method thereof, which is composed of 4, 4'-diamino-4''-hydroxytriphenylmethane DAHTM, double-terminated aminopropyl polydimethylsiloxane YASI, N, N, N', N'-tetraglycidyl-4, 4'-diaminodiphenylmethane TGDDM, a reaction product of an aromatic diamine, an aromatic dibasic anhydride and 3-aminopropyltrialkoxysilane, and an organic solvent.

[0015] Some of the phenolic resins in the prior art do not have allyl flexible groups, resulting in poor self-toughening effect; even if some phenolic resins have allyl flexible groups, the degree of reaction during the preparation process is usually low, and the allyl phenolic resins have few rigid groups and insufficient heat resistance. Summary of the invention

[0016] In order to solve the above problems, the present application provides an allylated maleimide phenolic resin having a large number of flexible groups (allyl groups) and a large number of heat-resistant groups (imide rings), which can further improve the residual carbon rate, intrinsic flame retardancy and heat resistance after being fully cured at high temperature. At the same time, the present application also provides a preparation method of the above phenolic resin, which has a simple process, a high degree of reaction, and a low raw material cost, and is conducive to industrial production.

[0017] Specifically, the technical solution of this application is as follows:

[0018] 1. An allylated maleimide phenolic resin, the structural formula of which is shown in the following formula (I):

[0019] Formula (I);

[0020] Wherein, n is selected from an integer ranging from 60 to 80.

[0021] 2. The allylated maleimide phenolic resin according to claim 1, wherein the ratio of the weight average molecular weight to the number average molecular weight (Mw / Mn) of the allylated maleimide phenolic resin is 1.01 to 1.25;

[0022] Preferably, the number average molecular weight of the allylated maleimide phenolic resin is 14000-18000 g / mol.

[0023] 3. The method for preparing the allylated maleimide phenolic resin according to item 1 or 2, comprising the following steps:

[0024] Acylation reaction: adding p-aminophenol, maleic anhydride and an organic solvent into a reactor to carry out an acylation reaction;

[0025] Salt-forming reaction: adding a salt-forming agent to the product of the acylation reaction to carry out a salt-forming reaction;

[0026] Etherification reaction: adding allyl halide to the product of the salt-forming reaction to carry out etherification reaction;

[0027] Polycondensation reaction: adding catalyst I to the product of the etherification reaction, and then dropping formaldehyde solution to carry out polycondensation reaction;

[0028] Imidization reaction: Add catalyst II to the product of the polycondensation reaction to carry out an imidization reaction to obtain an allylated maleimide phenolic resin.

[0029] 4. The preparation method according to item 3, wherein in the acylation reaction step, the molar ratio of p-aminophenol to maleic anhydride is 1:(1-2);

[0030] Preferably, the mass of the organic solvent is 1 to 6 times the total mass of the p-aminophenol and maleic anhydride.

[0031] 5. The preparation method according to item 3 or 4, wherein the organic solvent is selected from any one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethyl sulfoxide, benzene, toluene, xylene, ethylbenzene, monochlorobenzene and dichlorobenzene;

[0032] Preferably, the acylation reaction temperature is 20-35° C., and the acylation reaction time is 1-2 h.

[0033] 6. The preparation method according to any one of items 3 to 5, wherein in the salt-forming reaction step, the molar ratio of the salt-forming agent to p-aminophenol is (1 to 1.5):1;

[0034] Preferably, the salt-forming agent is selected from any one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, lithium carbonate and potassium carbonate;

[0035] Preferably, the salt-forming reaction temperature is 20-50°C;

[0036] Preferably, after the salt-forming reaction step and before the etherification reaction step, heating reflux to separate water is performed.

[0037] 7. The preparation method according to any one of items 3 to 6, wherein in the etherification reaction step, the molar ratio of the allyl halide to the aminophenol is (1 to 2): 1;

[0038] Preferably, the etherification reaction temperature is 40-90°C, more preferably 50-60°C;

[0039] Preferably, the etherification reaction time is 2 to 10 hours;

[0040] Preferably, the allyl halide is selected from any one of allyl fluoride, allyl chloride, allyl bromide and allyl iodide.

[0041] 8. The preparation method according to any one of items 3 to 7, wherein in the polycondensation reaction step, the mass percentage concentration of the formaldehyde solution is 40% to 60%;

[0042] Preferably, the molar ratio of formaldehyde to p-aminophenol is (0.7-2):1;

[0043] Preferably, the mass ratio of the catalyst I to p-aminophenol is (0.05-0.5):1.

[0044] 9. The preparation method according to any one of items 3 to 8, wherein in the polycondensation reaction step, the catalyst I is selected from any one or more of sulfuric acid, phosphoric acid, hydrochloric acid, oxalic acid, methanesulfonic acid, p-toluenesulfonic acid, o-toluenesulfonic acid, m-toluenesulfonic acid, hydroxybenzenesulfonic acid, benzenesulfonic acid, alkyl-substituted sulfonic acid, zinc acetate, magnesium acetate, sodium acetate and potassium acetate;

[0045] Preferably, the polycondensation reaction temperature is 50-110°C, more preferably 80-90°C;

[0046] Preferably, the polycondensation reaction time is 2 to 9 hours.

[0047] 10. The preparation method according to any one of items 3 to 9, wherein in the imidization step, the mass ratio of the catalyst II to p-aminophenol is (0.1 to 0.8):1;

[0048] Preferably, the catalyst II is selected from any one or more of sulfuric acid, phosphoric acid, hydrochloric acid, oxalic acid, methanesulfonic acid, p-toluenesulfonic acid, o-toluenesulfonic acid, m-toluenesulfonic acid, hydroxybenzenesulfonic acid, benzenesulfonic acid and alkyl-substituted sulfonic acid;

[0049] Preferably, the imidization reaction temperature is 90-130°C;

[0050] Preferably, the imidization reaction time is 3 to 8 hours;

[0051] Preferably, the imidization reaction is carried out while reflux water separation is performed.

[0052] Effects of the Invention

[0053] (1) The allylated maleimide phenolic resin of the present application has both a large number of flexible groups (allyl groups) and a large number of heat-resistant groups (imide rings), has a self-toughening effect and good thermal properties, and at the same time, has a very low free formaldehyde content and excellent heat resistance. The allylated maleimide phenolic resin of the present application can further improve the residual carbon rate, intrinsic flame retardancy and heat resistance after being fully cured at high temperature, and can be applied to high-tech fields such as high-temperature resistant intrinsic flame retardant coatings, high-temperature resistant intrinsic flame retardant adhesives, high-temperature resistant intrinsic electrical insulation materials, high-temperature resistant intrinsic flame retardant advanced composite materials, and high-temperature resistant intrinsic flame retardant copper clad laminates, and has excellent market application prospects.

[0054] (2) The preparation method of the present application is carried out under normal pressure, the reaction conditions are mild, the reaction is sufficient, the process is simple, the raw materials are easily available, the cost is low, and it is conducive to industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 This is the FTIR infrared spectrum of the allylated maleimide phenolic resin, the product of Example 1 of the present application. DETAILED DESCRIPTION

[0056] The present application will be described in detail below in conjunction with the accompanying drawings. It should be noted that "including" or "comprising" as mentioned throughout the specification and claims is an open term and should be interpreted as "including but not limited to". The subsequent description of the specification is a preferred embodiment of the present application, but the description is for the purpose of illustrating the general principles of the present application and is not intended to limit the scope of the present application. The scope of protection of the present application shall be determined by the attached claims.

[0057] <Allylated maleimide phenolic resin>

[0058] The structural formula of the allylated maleimide phenolic resin of the present application is shown in the following formula (I):

[0059] Formula (I).

[0060] In formula (1), n ​​is an integer of 60 to 80, for example, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80.

[0061] The allylated maleimide phenolic resin (also referred to as APMI-F resin) of the present application is brown, has a large number of flexible groups (allyl groups) and a large number of heat-resistant groups (imide rings), has a self-toughening effect and good thermal properties, and has a very low free formaldehyde content and excellent heat resistance.

[0062] In some embodiments, the ratio of the weight average molecular weight to the number average molecular weight of the allylated maleimide phenolic resin, Mw / Mn, is 1.01 to 1.25, for example, 1.02, 1.03, 1.04, 1.05, 1.06, 1.072, 1.08, 1.1, 1.11, 1.12, 1.13, 1.14, 1.15, 1.16, 1.17, 1.18, 1.197, 1.21, etc.

[0063] In the present application, the number average molecular weight can be determined by using Agilent's gel permeation chromatograph 1260 infinity II with DMF as the mobile phase.

[0064] In some embodiments, the specific method for determining the number average molecular weight is as follows:

[0065] a. Use a measuring cylinder to take 500 ml of DMF mobile phase and pour it into a brown vial, and add 100 μL of toluene as a solvent for standby use;

[0066] b. Accurately weigh 0.0060~0.0120g (accurate to 0.0001g) of sample into a sample dissolving bottle, use a 5ml glass syringe to draw the corresponding volume of solution from the brown vial to dissolve the sample, and prepare a 0.3% (m / v) sample solution; for special samples, the concentration can be adjusted according to the sample absorption;

[0067] c. Shake the sample to completely dissolve the sample;

[0068] d. Filter the sample into a new 2 ml injection bottle and place the filtered samples into the sample tray of the automatic sampler in sequence; the detection wavelength is 270 nm and the detection temperature is 40°C.

[0069] In some embodiments, the number average molecular weight of the allylated maleimide phenolic resin of the present application is 14000~18000 g / mol, for example, it can be 14000~15000 g / mol, 14000~16000 g / mol, 14000~17000 g / mol, 14000~18000 g / mol, 15000~16000 g / mol, 15000~17000 g / mol, 15000~18000 g / mol, 16000~17000 g / mol, 16000~18000 g / mol, etc.

[0070] In the present application, the weight average molecular weight can be determined by using Agilent's gel permeation chromatograph 1260 infinity II with DMF as the mobile phase.

[0071] In some embodiments, the specific method for determining the weight average molecular weight is as follows:

[0072] a. Use a measuring cylinder to take 500 ml of DMF mobile phase and pour it into a brown vial, and add 100 μL of toluene as a solvent for standby use;

[0073] b. Accurately weigh 0.0060~0.0120g (accurate to 0.0001g) of sample into a sample dissolving bottle, use a 5ml glass syringe to draw the corresponding volume of solution from the brown vial to dissolve the sample, and prepare a 0.3% (m / v) sample solution; for special samples, the concentration can be adjusted according to the sample absorption;

[0074] c. Shake the sample to completely dissolve the sample;

[0075] d. Filter the sample into a new 2 ml injection bottle and place the filtered samples into the sample tray of the automatic sampler in sequence; the detection wavelength is 270 nm and the detection temperature is 40°C.

[0076] The full name of "TGA test" in this application is thermogravimetric analysis (Thermo-Gravimetric Analysis), which is an important material analysis method. It mainly reveals the thermal stability and thermal decomposition behavior of the material by measuring and analyzing the weight change of the material during heating. In the TGA test, the sample is heated and gradually loses weight, and this process is accurately recorded. By analyzing the curve of weight change with temperature, researchers can obtain important information about the thermal stability and thermal decomposition behavior of the material. First, the TGA test can be used to study the thermal stability of the material. When the material is heated, its molecular structure may change, such as decomposition, oxidation or cross-linking. By observing the change of weight with temperature, researchers can understand at what temperature the material begins to lose weight and how the rate of weight loss is. This information is very important for understanding the thermal stability and potential heat resistance of the material. Secondly, the TGA test can also be used to study the thermal decomposition behavior of the material. When the material decomposes at high temperature, its molecular structure changes and releases gas or volatile substances. By observing the change of weight with temperature, researchers can understand at what temperature the material begins to decompose and how the decomposition rate is. For example, the present application can be tested using a TGA Q50 thermogravimetric analyzer from TA Corporation of the United States.

[0077] <Method for preparing allylated maleimide phenolic resin>

[0078] The preparation method of the allylated maleimide phenolic resin of the present application comprises the following steps:

[0079] (1) Acylation reaction: adding p-aminophenol, maleic anhydride and an organic solvent into a reactor to carry out an acylation reaction to obtain N-(4-hydroxyphenyl)maleamic acid;

[0080] (2) salt-forming reaction: adding a salt-forming agent to the product of the acylation reaction to carry out a salt-forming reaction to obtain N-(4-hydroxyphenyl)maleamic acid;

[0081] (3) Etherification reaction: adding an allyl halide to the product of the salt-forming reaction to carry out an etherification reaction to obtain N-(4-allyl ether phenyl) maleamic acid;

[0082] (4) polycondensation reaction: adding catalyst I to the product of the etherification reaction, and then dropping formaldehyde solution to carry out polycondensation reaction to obtain a polyallylated maleamic acid-based phenolic resin;

[0083] (5) Imidization reaction: Adding catalyst II to the product of the polycondensation reaction to carry out an imidization reaction to obtain an allylated maleimide phenolic resin having a structure represented by formula (I).

[0084] Formula (I);

[0085] Wherein, in formula (I), n is selected from an integer of 60 to 80.

[0086] In the prior art, monomers are usually imidized to obtain N-(4-hydroxyphenyl) maleimide, which is then polycondensed with formaldehyde, and the degree of reaction is low. However, the present application first polycondenses to obtain a polymer of a polyallylated maleamic acid-based phenolic resin, and then imidizes the polymer, and the degree of reaction is high. In addition, the present application performs a polycondensation reaction after the monomers are completely allylated by an etherification reaction, so that the finally obtained allylated maleimide-based phenolic resin is a completely allylated resin.

[0087] In the acylation step of the present application, p-aminophenol reacts with maleic anhydride to generate N-(4-hydroxyphenyl)maleamic acid, the structural formula of which is .

[0088] In some embodiments, in the acylation reaction step, the molar ratio of p-aminophenol to maleic anhydride is 1:(1-2), for example, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2, etc.

[0089] In some embodiments, the organic solvent is selected from any one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethyl sulfoxide, benzene, toluene, xylene, ethylbenzene, monochlorobenzene and dichlorobenzene. p-Aminophenol and maleic anhydride have high solubility in the above organic solvents, which is conducive to full contact of reactants, improves the reaction rate, and ensures uniform temperature and mild reaction.

[0090] In some embodiments, the organic solvent is N,N dimethylformamide and xylene. In some embodiments, the organic solvent is N,N dimethylacetamide and toluene. In some embodiments, the organic solvent is N-methyl-2-pyrrolidone and toluene.

[0091] In some embodiments, the mass of the organic solvent is 1 to 6 times the total mass of the p-aminophenol and maleic anhydride, for example, 1 time, 1.5 times, 2 times, 2.5 times, 3 times, 3.5 times, 4.5 times, 5 times, 5.5 times, 6 times, etc. Controlling the multiple relationship between the mass of the organic solvent and the total mass of p-aminophenol and maleic anhydride can ensure that p-aminophenol is fully reacted to increase the yield of the allylated maleimidophenol-formaldehyde resin.

[0092] In some embodiments, the acylation reaction temperature is 20-35°C, for example, 20°C, 22°C, 24°C, 26°C, 28°C, 30°C, 32°C, 35°C or room temperature; the acylation reaction time is 1-2h, for example, 1h, 1.2h, 1.4h, 1.6h, 1.8h, 2h, etc.

[0093] In some embodiments, the organic solvent is selected from any one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethyl sulfoxide, benzene, toluene, xylene, ethylbenzene, monochlorobenzene and dichlorobenzene, and the mass of the organic solvent is 1 to 6 times the total mass of the p-aminophenol and maleic anhydride.

[0094] In the present application, the salt-forming agent reacts with N-(4-hydroxyphenyl)maleamic acid to generate N-(4-hydroxyphenyl)maleamic acid, which is convenient for the subsequent etherification reaction, and the imine ring is hydrolyzed to a certain extent under alkaline conditions, so the use of the salt-forming agent is critical. In some embodiments, the salt-forming agent is selected from any one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, lithium carbonate and potassium carbonate.

[0095] In some embodiments, the molar ratio of the salt-forming agent to p-aminophenol is (1-1.5):1, for example, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, etc. The salt-forming agent is alkaline. If it is too much, the alkalinity is too strong, resulting in hydrolysis of the imine ring and increased side reactions. If it is too little, too little phenolate is formed, which is not conducive to allylation.

[0096] In some embodiments, the salt-forming agent is selected from any one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, lithium carbonate and potassium carbonate, and the molar ratio of the salt-forming agent to p-aminophenol is (1-1.5):1.

[0097] In some embodiments, the salt-forming reaction temperature is 20-50°C, for example, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, or 50°C.

[0098] In some embodiments, after the salt-forming reaction step and before the etherification reaction step, heating reflux water separation is performed. The salt-forming reaction will generate water, which is not conducive to the etherification reaction. Heating reflux water separation can promote the reaction to proceed in the forward direction. In some embodiments, the heating reflux water separation time is 2 to 5 hours, for example, it can be 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, etc.; the heating reflux water separation temperature is 90 to 120°C, for example, it can be 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, etc.

[0099] In some embodiments, the etherification reaction temperature is 40-90° C., for example, 40° C., 45° C., 50° C., 55° C., 60° C., 65° C., 70° C., 75° C., 80° C., 85° C., 90° C., etc., and more preferably 50-60° C. The etherification reaction temperature is controlled within the above range to ensure a high degree of etherification reaction. If the temperature is too low, the reaction is slow. If the temperature is too high, the allyl halide volatilizes before it has time to react. At the same time, the temperature is too high.

[0100] In some embodiments, the etherification reaction time is 2 to 10 hours, for example, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, etc.

[0101] In some embodiments, the etherification reaction temperature is 40-90°C, and the etherification reaction time is 2-10 hours. In some embodiments, the etherification reaction temperature is 50-60°C, and the etherification reaction time is 2-10 hours.

[0102] In some embodiments, the allyl halide is selected from any one of allyl fluoride, allyl chloride, allyl bromide and allyl iodide, and the molar ratio of the allyl halide to the aminophenol is (1-2):1, for example, 1.2:1, 1.4:1, 1.6:1, 1.8:1, 2:1, etc.

[0103] In the polycondensation reaction step of the present application, N-(4-allyl ether phenyl) maleamic acid reacts with formaldehyde to generate polyallylated maleamic acid-based phenolic resin. The present application selects N-(4-allyl ether phenyl) maleamic acid monomer and formaldehyde to carry out polycondensation reaction, and the reaction degree is high, free monomer is few, and the waste of raw materials is reduced, and the molecular weight of the final product phenolic resin is higher, and its thermal performance and mechanical properties can also be improved. In the present application, the reaction degree refers to the fraction of the number of groups participating in the reaction to the number of starting groups, and the amount used to characterize the reaction depth of the polymer polymerization reaction in the polymer polycondensation reaction.

[0104] In some embodiments, in the polycondensation step, catalyst I is selected from any one or more of sulfuric acid, phosphoric acid, hydrochloric acid, oxalic acid, methanesulfonic acid, p-toluenesulfonic acid, o-toluenesulfonic acid, m-toluenesulfonic acid, hydroxybenzenesulfonic acid, benzenesulfonic acid, alkyl substituted sulfonic acid, zinc acetate, nickel acetate, magnesium acetate, sodium acetate and potassium acetate. Using the above catalyst I to carry out polycondensation reaction can accelerate the reaction rate to obtain high ortho-resin. In some preferred embodiments, catalyst I is selected from any one or more of sulfuric acid, phosphoric acid, oxalic acid, methanesulfonic acid, p-toluenesulfonic acid, o-toluenesulfonic acid, m-toluenesulfonic acid, zinc acetate, nickel acetate and magnesium acetate.

[0105] In some embodiments, the mass ratio of catalyst I to p-aminophenol is (0.05~0.5):1, for example, it can be 0.05:1, 0.06:1, 0.07:1, 0.08:1, 0.09:1, 0.1:1, 0.15:1, 0.2:1, 0.25:1, 0.3:1, 0.35:1, 0.4:1, 0.45:1, 0.5:1, etc.

[0106] In some embodiments, catalyst I is selected from any one or more of sulfuric acid, phosphoric acid, hydrochloric acid, oxalic acid, methanesulfonic acid, p-toluenesulfonic acid, o-toluenesulfonic acid, m-toluenesulfonic acid, hydroxybenzenesulfonic acid, benzenesulfonic acid, alkyl-substituted sulfonic acid, zinc acetate, magnesium acetate, sodium acetate and potassium acetate, and the mass ratio of catalyst I to p-aminophenol is (0.05~0.5):1.

[0107] In some embodiments, the polycondensation reaction temperature is 50-110°C. If the polycondensation reaction temperature is too low, the reaction rate is slow, and if the polycondensation reaction temperature is too high, more side reactions will occur. For example, it can be 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C, 90°C, 95°C, 100°C, 105°C, 110°C, etc., and more preferably 80-90°C.

[0108] In some embodiments, the polycondensation reaction time is 2 to 9 hours, for example, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, etc. Controlling the polycondensation reaction time within the above range can further ensure a higher degree of reaction.

[0109] In some embodiments, the polycondensation reaction temperature is 50-110° C., and the polycondensation reaction time is 2-9 hours. In some embodiments, the polycondensation reaction temperature is 80-90° C., and the polycondensation reaction time is 2-9 hours.

[0110] In some embodiments, catalyst I is selected from any one or more of sulfuric acid, phosphoric acid, hydrochloric acid, oxalic acid, methanesulfonic acid, p-toluenesulfonic acid, o-toluenesulfonic acid, m-toluenesulfonic acid, hydroxybenzenesulfonic acid, benzenesulfonic acid, alkyl-substituted sulfonic acid, zinc acetate, magnesium acetate, sodium acetate and potassium acetate, and the polycondensation reaction temperature is 80-90°C.

[0111] In some embodiments, the mass percentage concentration of the formaldehyde solution is 40% to 60%, for example, 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, 60%, etc., and the molar ratio of formaldehyde to p-aminophenol is (0.7 to 2):1, for example, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2:1, etc.;

[0112] In the imidization step of the present application, the polyallylated maleamic acid-based phenolic resin is dehydrated and ring-closed to generate the allylated maleimide-based phenolic resin.

[0113] In some embodiments, catalyst II is selected from any one or more of sulfuric acid, phosphoric acid, hydrochloric acid, oxalic acid, methanesulfonic acid, p-toluenesulfonic acid, o-toluenesulfonic acid, m-toluenesulfonic acid, hydroxybenzenesulfonic acid, benzenesulfonic acid and alkyl substituted sulfonic acid. The use of the above catalyst II can effectively promote the imidization reaction. In some preferred embodiments, catalyst II is selected from any one or more of sulfuric acid, phosphoric acid, p-toluenesulfonic acid, o-toluenesulfonic acid and m-toluenesulfonic acid.

[0114] In some embodiments, the mass ratio of catalyst II to p-aminophenol is (0.1~0.8):1, for example, it can be 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, etc.

[0115] In some embodiments, the imidization reaction temperature is 90-130° C. By controlling the imidization reaction temperature within the above range, the polyallylated maleamic acid-based phenolic resin can be completely imidized.

[0116] In some embodiments, the imidization reaction time is 3 to 8 hours, for example, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, etc. Controlling the imidization reaction time within the above range can ensure a high degree of imidization.

[0117] In some embodiments, the imidization reaction temperature is 90-120°C, and the imidization reaction time is 3-8 hours. In some embodiments, the imidization reaction temperature is 110-130°C, and the imidization reaction time is 3-8 hours. In some embodiments, the imidization reaction temperature is 100-120°C, and the imidization reaction time is 3-8 hours.

[0118] In some embodiments, the catalyst II is selected from any one or more of sulfuric acid, phosphoric acid, hydrochloric acid, oxalic acid, methanesulfonic acid, p-toluenesulfonic acid, o-toluenesulfonic acid, m-toluenesulfonic acid, hydroxybenzenesulfonic acid, benzenesulfonic acid and alkyl substituted sulfonic acid, and the imidization reaction temperature is 90-120°C. In some embodiments, the catalyst II is selected from any one or more of sulfuric acid, phosphoric acid, hydrochloric acid, oxalic acid, methanesulfonic acid, p-toluenesulfonic acid, o-toluenesulfonic acid, m-toluenesulfonic acid, hydroxybenzenesulfonic acid, benzenesulfonic acid and alkyl substituted sulfonic acid, and the imidization reaction temperature is 110-130°C. In some embodiments, the catalyst II is selected from any one or more of sulfuric acid, phosphoric acid, hydrochloric acid, oxalic acid, methanesulfonic acid, p-toluenesulfonic acid, o-toluenesulfonic acid, m-toluenesulfonic acid, hydroxybenzenesulfonic acid, benzenesulfonic acid and alkyl substituted sulfonic acid, and the imidization reaction temperature is 100-120°C.

[0119] In some embodiments, reflux and water separation are performed during the imidization reaction to promote the forward progress of the reaction.

[0120] The allylated maleimide phenolic resin of the present application has excellent thermal decomposition performance. During the curing process at 220°C for 2h, the temperature of the resin when it loses 5% of its weight by heat is generally above 280°C, and can even reach 308.34°C. The temperature of the resin when it loses 10% of its weight by heat is generally above 290°C, and can even reach 318.37°C. The allylated maleimide phenolic resin has a high residual carbon rate, and the residual carbon rate at 800°C is generally above 40%, and can reach up to 49.79%; the yield is above 70%, and can even reach 83.9%. The allylated maleimide phenolic resin has a high molecular weight, a large number of flexible groups (allyl groups) and a large number of heat-resistant groups (imide rings), has a self-toughening effect and good thermal properties, and a weight average molecular weight of more than 17,000, and can even reach 19,827; the ratio of the weight average molecular weight to the number average molecular weight is close to 1, and can even reach 1.09~1.11. At the same time, the free formaldehyde content of allylated maleimide phenolic resin is very low, below 1% overall, and can even reach 0.32%, with excellent heat resistance.

[0121] Example

[0122] In order to make the objectives, technical solutions and advantages of the present application more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0123] In the following examples, the sources of some materials and reagents are shown in Table 1 below:

[0124] Table 1

[0125] .

[0126] Example 1

[0127] 54.5 g (0.5 mol) of p-aminophenol, 49.0 g (0.5 mol) of maleic anhydride and an organic solvent (120 g of N, N-dimethylformamide and 130 g of xylene) were placed in a reactor, and the acylation reaction was carried out under stirring at room temperature for 1 hour. Then, 103.5 g (0.75 mol) of anhydrous carbonic acid (salting agent) was added to the product of the acylation reaction, and a salt-forming reaction occurred at 30°C. Then, the mixture was refluxed for 4 hours to separate water, and 38.2 g (0.5 mol) of allyl chloride was added. The etherification reaction was carried out under stirring at 50°C for 4 hours. Then, 28 g of sulfuric acid (catalyst) with a mass fraction of 20% was added to the product of the etherification reaction. I), add 31.3g of formaldehyde solution with a mass fraction of 48%, after the addition is completed, heat to 80°C, stir to carry out polycondensation reaction for 5h, cool to 60°C, add 8.2g of oxalic acid (catalyst II), at 90~130°C, imidization reaction for 4h, reflux water separation during imidization reaction, filter to remove insoluble solid matter, mother liquor (containing product resin, very little catalyst in the reaction process, allyl chloride mixed organic solution) is heated, separate and recover excess allyl chloride and organic solvent, and then wash with water to obtain 108.5g of allyl maleimide phenolic resin with structure shown in formula (I). The resin sample of formula (I) of this embodiment is mixed with potassium bromide powder, ground into powder and pressed into tablets, and then Fourier transform infrared spectrometer (NICOLET6700, Thermo Fisher Scientific, USA) is used for infrared spectrum test to obtain its FTIR infrared spectrum as shown in Figure 1 shown.

[0128] Example 2

[0129] 54.5 g (0.5 mol) of p-aminophenol, 49.0 g (0.5 mol) of maleic anhydride and an organic solvent (120 g of N, N-dimethylacetamide and 120 g of toluene) were placed in a reactor, and the acylation reaction was carried out under stirring at room temperature for 2 h. Then, 65.6 g (0.625 mol) of sodium carbonate (salting agent) was added to the product of the acylation reaction, and a salt-forming reaction occurred at 30 ° C. Then, the mixture was refluxed for 5 h, 45.6 g (0.6 mol) of allyl chloride was added, and the etherification reaction was carried out under stirring at 50 ° C for 5 h. Subsequently, 28 g of 20% by mass phosphoric acid (catalyst I) was added to the product of the etherification reaction, and 30 g of After the addition of the formaldehyde solution with a mass fraction of 48%, the mixture was heated to 80°C and stirred for condensation reaction for 5 hours. The mixture was cooled to 60°C, and 16.63g of hydrochloric acid with a mass fraction of 20% (catalyst II) was added. The imidization reaction was carried out at 90-130°C for 5 hours. During the imidization reaction, the mixture was refluxed and water was separated. Insoluble solid matter was removed by filtration. The mother liquor was heated to a temperature of 100°C, and excess allyl chloride and organic solvent were separated and recovered. The mixture was then washed with water to obtain 119.8g of allylated maleimidophenol-formaldehyde resin having a structure represented by formula (I).

[0130] Example 3

[0131] 54.5 g (0.5 mol) of p-aminophenol, 49.0 g (0.5 mol) of maleic anhydride and an organic solvent (350 g of N-methyl-2-pyrrolidone and 270 g of toluene) were placed in a reactor, and an acylation reaction was carried out at room temperature with stirring for 2 h. Then, 22.0 g (0.55 mol) of sodium hydroxide (salting agent) was added to the product of the acylation reaction, and a salt-forming reaction occurred at 30°C. Then, the mixture was refluxed for 4.5 h, 41.8 g (0.55 mol) of allyl chloride was added, and an etherification reaction was carried out at 50°C with stirring for 8 h. Subsequently, 9.8 g of p-toluenesulfonic acid (catalyst I) was added to the product of the etherification reaction, and 28.1 g of a formaldehyde solution with a mass fraction of 48% was added dropwise. After the addition was completed, the mixture was heated to 85°C, stirred for 6 h for a polycondensation reaction, cooled to 50°C, and 10.37 g of 85% phosphoric acid (catalyst II), at 90 ~ 130 ℃, imidization reaction for 6h, reflux water separation during the imidization reaction, filter to remove insoluble solid matter, heat the mother liquor to raise the temperature, separate and recover excess allyl chloride and organic solvent, and then wash with water to obtain 127.9g of allylated maleimide phenolic resin with the structure shown in formula (I).

[0132] Example 4

[0133] 54.5 g (0.5 mol) of p-aminophenol, 49.0 g (0.5 mol) of maleic anhydride and an organic solvent (90 g of N-methyl-2-pyrrolidone and 20 g of toluene) were placed in a reactor, and the acylation reaction was carried out for 2 h under stirring at room temperature. Then, 36.4 g (0.65 mol) of potassium hydroxide (salting agent) was added to the product of the acylation reaction, and the salt-forming reaction occurred at 30°C. Then, the mixture was refluxed for 4.5 h, cooled to 50°C, and 41.8 g (0.55 mol) of allyl chloride was added. The etherification reaction was carried out for 7 h under stirring. Then, the product of the etherification reaction was added. 9.8 g of p-toluenesulfonic acid (catalyst I) was added, and 25 g of a formaldehyde solution with a mass fraction of 48% was added dropwise. After the addition was completed, the mixture was heated to 90°C and stirred for polycondensation for 6 h. The mixture was cooled to 50°C, and 8.1 g of oxalic acid (catalyst II) was added. The imidization reaction was carried out at 90-130°C for 5 h. During the imidization reaction, reflux and water separation were carried out, and insoluble solid matter was removed by filtration. The mother liquor was heated to a temperature of 100 °C, and excess allyl chloride and organic solvent were separated and recovered. The mixture was washed with water to obtain 119.7 g of an allylated maleimidophenol-formaldehyde resin having a structure represented by formula (I).

[0134] Example 5

[0135] The only difference between this embodiment and embodiment 3 is that the temperature is raised to 80° C. and the polycondensation reaction is carried out with stirring.

[0136] Example 6

[0137] The only difference between this embodiment and embodiment 3 is that the temperature is raised to 90° C. and the polycondensation reaction is carried out by stirring.

[0138] Example 7

[0139] The only difference between this embodiment and embodiment 3 is that the temperature is raised to 50° C. and the polycondensation reaction is carried out with stirring.

[0140] Example 8

[0141] The only difference between this embodiment and embodiment 3 is that the temperature is raised to 110° C. and the polycondensation reaction is carried out with stirring.

[0142] Example 9

[0143] The only difference between this embodiment and embodiment 3 is that the temperature is raised to 45° C. and the polycondensation reaction is carried out with stirring.

[0144] Example 10

[0145] The only difference between this embodiment and embodiment 6 is that the etherification reaction is carried out at 60° C. with stirring.

[0146] Embodiment 11

[0147] The only difference between this embodiment and embodiment 10 is that the etherification reaction is carried out at 40° C. with stirring.

[0148] Example 12

[0149] The only difference between this embodiment and embodiment 10 is that the etherification reaction is carried out at 90° C. with stirring.

[0150] Example 13

[0151] The only difference between this example and Example 10 is that the etherification reaction is carried out at 35° C. with stirring.

[0152] Embodiment 14

[0153] The only difference between this embodiment and embodiment 10 is that catalyst I is 9.8 g of zinc acetate and 0.36 g of oxalic acid.

[0154] Embodiment 15

[0155] The difference between this embodiment and embodiment 14 is only that catalyst I is 10.46g of zinc acetate.

[0156] Example 16

[0157] The only difference between this embodiment and embodiment 14 is that catalyst I is 5.13 g of oxalic acid.

[0158] Embodiment 17

[0159] The only difference between this embodiment and embodiment 14 is that the catalyst II is 44.1 g of 20% sulfuric acid by mass.

[0160] Embodiment 18

[0161] The only difference between this embodiment and embodiment 17 is that catalyst II is 15.5 g of p-toluenesulfonic acid.

[0162] Comparative Example 1

[0163] 54.5 g (0.5 mol) of p-aminophenol, 49.0 g (0.5 mol) of maleic anhydride and an organic solvent (350 g of N-methyl-2-pyrrolidone and 270 g of toluene) were placed in a reactor, and the acylation reaction was carried out under stirring at room temperature for 2 h. Then, 10.37 g of 85% phosphoric acid (catalyst II), at 90-130°C, imidization reaction for 6h, reflux and water separation are carried out at the same time of imidization reaction, after the imidization reaction, 9.8g of p-toluenesulfonic acid (catalyst I) is added, 28.1g of formaldehyde solution with a mass fraction of 48% is added dropwise, after the dropwise addition is completed, the temperature is raised to 85°C, stirred for polycondensation reaction for 6h, cooled to 50°C, and then 103.5g (0.75mol) of anhydrous potassium carbonate (salting agent) is added, and salt formation reaction occurs at 30°C, and then reflux and water separation is carried out for 4.5h, 41.8g (0.55mol) of allyl chloride is added, and etherification reaction is carried out at 50°C with stirring for 8h, insoluble solid matter is filtered to remove, the mother liquor is heated to raise the temperature, excess allyl chloride and organic solvent are separated and recovered, and then washed with water to obtain 105.1g of allylated maleimide phenolic resin with the structure shown in formula (II). Among them, n1 is 20~50, and n2 is 20~50.

[0164] Formula (II).

[0165] Comparative Example 2

[0166] 54.5 g (0.5 mol) of p-aminophenol, 49.0 g (0.5 mol) of maleic anhydride and an organic solvent (350 g of N-methyl-2-pyrrolidone and 270 g of toluene) were placed in a reactor, and the acylation reaction was carried out for 2 h under stirring at room temperature. Then, 9.8 g of p-toluenesulfonic acid (catalyst I) was added to the product of the acylation reaction, and 28.1 g of a formaldehyde solution with a mass fraction of 48% was added dropwise. After the addition was completed, the temperature was raised to 85°C, and the polycondensation reaction was carried out for 6 h under stirring. The reaction was cooled to 50°C, and 10.37 g of 85% phosphoric acid (catalyst II), imidization reaction at 90-130°C for 6h, reflux and water separation at the same time, then add 22.0g (0.55mol) sodium hydroxide (salting agent), salt formation reaction at 30°C, then reflux and water separation for 4.5h, add 41.8g (0.55mol) allyl chloride, stir at 50°C for etherification reaction for 8h, filter to remove insoluble solid matter, heat the mother liquor to raise the temperature, separate and recover excess allyl chloride and organic solvent, and then wash with water to obtain 102.3g of allyl maleimide phenolic resin with the structure shown in formula (III). Wherein, n1 is 30-60, and n2 is 30-60.

[0167] Formula (III).

[0168] Test example

[0169] 1. Analysis of free aldehyde content and thermal decomposition performance during curing process

[0170] Samples were taken during the polycondensation process of each embodiment and comparative example, and free aldehydes were measured using the hydroxylamine hydrochloride method (GB / T 32684-2016). The thermal decomposition properties of the allylated maleimide-based phenol-formaldehyde resins during the curing process of each embodiment and comparative example were tested using TA's TGA Q50 thermogravimetric analyzer.

[0171] (1) The raw materials, raw material ratios and reaction conditions of Examples 1-4, as well as the measured free aldehyde content and thermal decomposition test results before and after curing are listed in the following Table 2. Wherein, Td5 refers to the temperature at which the resin loses 5% of its weight upon heating, and Td10 refers to the temperature at which the resin loses 10% of its weight upon heating.

[0172] Table 2

[0173] .

[0174] (2) The free formaldehyde content and thermal decomposition test results of the allylated maleimidophenol-formaldehyde resin before and after curing measured in Examples 3 and Examples 5 to 9 are listed in Table 3 below to analyze the effect of the polycondensation reaction temperature on the preparation process.

[0175] Table 3

[0176] .

[0177] (3) The free formaldehyde content and thermal decomposition test results of the allylated maleimide phenolic resin before and after curing measured in Example 6 and Examples 10 to 13 are listed in Table 4 below to analyze the effect of the etherification reaction temperature on the preparation process.

[0178] Table 4

[0179] .

[0180] (4) The free formaldehyde content and thermal decomposition test results of the allylated maleimidophenol-formaldehyde resin before and after curing measured in Example 10 and Examples 14 to 16 are listed in Table 5 below to analyze the effect of the selection of catalyst I on the preparation process.

[0181] Table 5

[0182] .

[0183] (5) The free formaldehyde content measured in Example 14 and Examples 17-18 and the thermal decomposition test results of the allylated maleimidophenol-formaldehyde resin before and after curing are listed in Table 6 below to analyze the effect of the selection of catalyst II on the preparation process.

[0184] Table 6

[0185] .

[0186] (6) The free formaldehyde content and thermal decomposition test results of the allylated maleimide phenolic resin before and after curing measured in Example 3 and Comparative Examples 1 and 2 are listed in Table 7 below to analyze the influence of the raw material monomer selection of the polycondensation reaction on the preparation process.

[0187] Table 7

[0188] .

[0189] 2. Impact performance test

[0190] The final product of the reaction, APMI-F resin, in Example 2, was uniformly mixed with bismaleimide resin (diphenylmethane bismaleimide resin (BDM), homemade in the laboratory) at different proportions at 150°C, and cured according to a curing process of 160°C / 2h-180°C2h-200°C / 1h-230°C / 1h-280°C / 1h to prepare a specimen for impact performance testing. The specimen was tested using a 251J-2 pendulum impact tester. The test results are shown in Table 8.

[0191] Table 8

[0192] .

[0193] The final product of the reaction, APMI-F resin, in Example 3, was uniformly mixed with bismaleimide resin (diphenylmethane bismaleimide resin (BDM), homemade in the laboratory) at different proportions at 150°C, and cured according to a curing process of 160°C / 2h-180°C2h-200°C / 1h-230°C / 1h-280°C / 1h to prepare specimens for impact performance testing. The specimens were tested using a 251J-2 pendulum impact tester, and the test results are shown in Table 9.

[0194] Table 9

[0195] .

[0196] The final product of the reaction, APMI-F resin, in Example 14, was uniformly mixed with bismaleimide resin (diphenylmethane bismaleimide resin (BDM), homemade in the laboratory) at different proportions at 150°C, and cured according to a curing process of 160°C / 2h-180°C2h-200°C / 1h-230°C / 1h-280°C / 1h to prepare a specimen for impact performance testing. The specimen was tested using a 251J-2 pendulum impact tester. The test results are shown in Table 10.

[0197] Table 10

[0198] .

[0199] The above is only the preferred embodiment of the present application, and does not limit the present application in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present application without departing from the content of the technical solution of the present application still falls within the protection scope of the technical solution of the present application.

Claims

1. An allylated maleimide phenolic resin, the structural formula of which is shown in the following formula (I): Formula (I); in, n is selected from an integer ranging from 60 to 80.

2. The allyl maleimide phenolic resin according to claim 1, wherein The ratio of the weight average molecular weight to the number average molecular weight of the allylated maleimide phenolic resin is 1.01 to 1.25; and / or The number average molecular weight of the allylated maleimide phenolic resin is 14000-18000 g / mol.

3. The method for preparing the allylated maleimide phenolic resin according to claim 1 or 2, comprising the steps of: Acylation reaction: adding p-aminophenol, maleic anhydride and an organic solvent into a reactor to carry out an acylation reaction; Salt-forming reaction: adding a salt-forming agent to the product of the acylation reaction to carry out a salt-forming reaction; Etherification reaction: adding allyl halide to the product of the salt-forming reaction to carry out etherification reaction; Polycondensation reaction: adding catalyst I to the product of the etherification reaction, and then dropping formaldehyde solution to carry out polycondensation reaction; Imidization reaction: Add catalyst II to the product of the polycondensation reaction to carry out an imidization reaction to obtain an allylated maleimide phenolic resin.

4. The preparation method according to claim 3, wherein In the acylation reaction step, the molar ratio of p-aminophenol to maleic anhydride is 1:(1-2); and / or The mass of the organic solvent is 1 to 6 times the total mass of the p-aminophenol and maleic anhydride.

5. The preparation method according to claim 3, wherein: The organic solvent is selected from any one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethyl sulfoxide, benzene, toluene, xylene, ethylbenzene, monochlorobenzene and dichlorobenzene; and / or The acylation reaction temperature is 20~35°C, and the acylation reaction time is 1~2h.

6. The preparation method according to claim 3, wherein: In the salt-forming reaction step, the molar ratio of the salt-forming agent to p-aminophenol is (1-1.5):1; and / or The salt-forming agent is selected from any one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, lithium carbonate and potassium carbonate; and / or The salt-forming reaction temperature is 20~50℃.

7. The preparation method according to claim 3, wherein: In the etherification reaction step, the molar ratio of the allyl halide to the aminophenol is (1-2):1; and / or The etherification reaction temperature is 40-90°C; and / or The allyl halide is selected from any one of allyl fluoride, allyl chloride, allyl bromide and allyl iodide.

8. The preparation method according to any one of claims 3 to 7, wherein In the polycondensation reaction step, the mass percentage concentration of the formaldehyde solution is 40% to 60%; and / or The molar ratio of formaldehyde to p-aminophenol is (0.7-2):1; and / or The mass ratio of the catalyst I to p-aminophenol is (0.05-0.5):

1.

9. The preparation method according to any one of claims 3 to 7, wherein In the polycondensation step, the catalyst I is selected from any one or more of sulfuric acid, phosphoric acid, hydrochloric acid, oxalic acid, methanesulfonic acid, p-toluenesulfonic acid, o-toluenesulfonic acid, m-toluenesulfonic acid, hydroxybenzenesulfonic acid, benzenesulfonic acid, alkyl-substituted sulfonic acid, zinc acetate, magnesium acetate, sodium acetate and potassium acetate; and / or The polycondensation reaction temperature is 50~110℃.

10. The preparation method according to any one of claims 3 to 7, wherein In the imidization step, the mass ratio of the catalyst II to p-aminophenol is (0.1-0.8):1; and / or The catalyst II is selected from any one or more of sulfuric acid, phosphoric acid, hydrochloric acid, oxalic acid, methanesulfonic acid, p-toluenesulfonic acid, o-toluenesulfonic acid, m-toluenesulfonic acid, hydroxybenzenesulfonic acid, benzenesulfonic acid and alkyl-substituted sulfonic acid; and / or The imidization reaction temperature is 90~130℃.

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