A modified benzoxazine resin, its preparation method and application

Abstract

This invention relates to the field of benzoxazines, and particularly to a modified benzoxazine resin, its preparation method, and its application. The method for preparing the modified benzoxazine resin includes the following steps: S1, First stage reaction: An alkane-based amine compound, formaldehyde, and an organic solvent are stirred evenly and heated to react; the alkane-based amine compound is one or more of short-chain aliphatic amines, alicyclic polyamines, and monoamine compounds; S2, Second stage reaction: A phenolic compound containing an unsaturated hydrocarbon group is added and heated to react; S3, Temperature is increased, and small molecule impurities and byproducts are removed under negative pressure to obtain the modified benzoxazine resin. This invention provides a modified benzoxazine resin, its preparation method, and its application, solving the problems of insufficient storage stability and processing performance of existing benzoxazine resins while improving dielectric properties.

Description

Technical Field

[0001] This invention relates to the field of benzoxazines, and more particularly to a modified benzoxazine resin, its preparation method, and its application. Background Technology

[0002] With the rapid development of artificial intelligence chips, 5G communications, and intelligent driving in new energy vehicles, electronic components are rapidly evolving towards higher speeds and greater integration. Under the condition of increased wiring density in very large-scale integrated circuits, the resistance of metal interconnects and the capacitance of interlayer dielectrics within electronic components can easily create an RC delay (resistance-capacitance delay) effect, leading to adverse effects such as signal transmission delay, noise interference, and power loss. To reduce interconnect delay, energy consumption, and crosstalk, it is necessary to develop dielectric materials with low dielectric constants (Dk and Df). The lower the dielectric constant of the material, the faster the signal transmission, the lower the signal delay, the lower the signal propagation loss rate, and the higher the signal fidelity.

[0003] Benzoxazine is a benzo-hexacyclic heterocyclic compound synthesized from phenolic compounds, amine compounds, and formaldehyde. Under heating or catalysis, it undergoes ring-opening polymerization to form a nitrogen-containing network polymer. It is a novel low-surface-energy material characterized by flexible molecular design, low curing volume shrinkage, and low surface energy. Commercially available benzoxazine resins, such as bisphenol (bisphenol F and bisphenol A) and diamine (ODA and DMA), can be used in printed circuit boards, meeting the needs of low- to mid-range applications. However, their high-frequency dielectric properties and heat resistance are insufficient for high-end integrated circuit dielectric materials. Therefore, it is necessary to reduce the polarity of the material to improve dielectric properties. However, while reducing the polarity, monophenolic monoamine monooxazine ring resins with low olefin groups are prone to incomplete polymerization and phase separation due to their small molecular weight. This results in insufficient heat resistance, poor storage stability, and poor processing performance, hindering their industrial application in high-frequency, high-speed electronic copper-clad laminates. Summary of the Invention

[0004] The purpose of this invention is to propose a modified benzoxazine resin, its preparation method and application, to solve the problems of insufficient storage stability and processing performance of existing benzoxazine resins while improving dielectric properties.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] A method for preparing a modified benzoxazine resin includes the following steps:

[0007] S1, First stage reaction: Stir the alkane-amine compound, formaldehyde and organic solvent evenly, and heat to react;

[0008] The alkane-based amine compound is one or more of short-chain aliphatic amines, alicyclic polyamines, and monoamine compounds;

[0009] S2, Second stage reaction: Add a phenolic compound containing an unsaturated hydrocarbon group and heat to react;

[0010] S3. Increase the temperature and apply negative pressure to remove small molecule impurities and byproducts, thus obtaining modified benzoxazine resin.

[0011] Preferably, the alkane-amine type compound is a diamine type compound and / or the phenolic type compound containing an unsaturated hydrocarbon group is a bisphenol type compound.

[0012] Preferably, in step S1, the temperature is raised to 60-90°C and maintained for 0.5-2 hours.

[0013] In step S2, the temperature is raised to 70-100℃ and maintained for 2-5 hours.

[0014] Preferably, the carbon chain length of the short aliphatic chain amine is C1-C4.

[0015] Preferably, the alicyclic polyamine is cyclohexanediamine, cyclopentanediamine, 4,4-diaminodicyclohexylmethane, cyclopropylamine, cyclopentaneamine, cyclohexylamine, cyclohexanedimethylamine, or cyclopentanedimethylamine.

[0016] Preferably, the unsaturated hydrocarbon phenolic compound is an allyl-substituted polyphenolic compound or an unsaturated hydrocarbon-substituted monophenolic compound.

[0017] Preferably, in step S1, the organic solvent is a polar or non-polar solvent with a boiling point not higher than 170°C.

[0018] In step S3, small molecule impurities and byproducts are removed under negative pressure at 100-170℃ for 1-6 hours.

[0019] A modified benzoxazine resin, prepared by any one of the above-described methods for preparing a modified benzoxazine resin, wherein the benzoxazine structure of the modified benzoxazine resin contains at least one unsaturated hydrocarbon group.

[0020] Furthermore, the modified benzoxazine resin has a weight-average molecular weight greater than 2000.

[0021] The application of any of the above-mentioned modified benzoxazine resins as circuit dielectric materials in high-frequency and high-speed electronic copper-clad laminates.

[0022] The technical solution provided by this invention may include the following beneficial effects:

[0023] This invention selects alkane-based primary amines and phenolic compounds containing unsaturated alkane groups as raw materials, introducing nonpolar alkane groups into the benzoxazine structure. This improves dielectric properties, storage stability, and processing performance. Simultaneously, the phased reaction effectively prevents the residue of strongly polar phenolic hydroxyl groups that have not participated in ring-closure dehydration, thereby improving dielectric insulation and meeting the industrial application requirements of high-frequency and high-speed electronic copper-clad laminates. Detailed Implementation

[0024] The technical solution of the present invention will be further illustrated below through specific embodiments.

[0025] To facilitate understanding of the present invention, a more complete description is provided below. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0026] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0027] A method for preparing a modified benzoxazine resin includes the following steps:

[0028] S1, First stage reaction: Stir the alkane-amine compound, formaldehyde and organic solvent evenly, and heat to react;

[0029] The alkane-based amine compound is one or more of short-chain aliphatic amines, alicyclic polyamines, and monoamine compounds;

[0030] S2, Second stage reaction: Add a phenolic compound containing an unsaturated hydrocarbon group and heat to react;

[0031] S3. Increase the temperature and apply negative pressure to remove small molecule impurities and byproducts, thus obtaining modified benzoxazine resin.

[0032] To address the problems existing in the prior art, this invention proposes a method for preparing modified benzoxazine resin. By selecting alkane-based primary amines and phenolic compounds containing unsaturated alkane groups as raw materials, nonpolar alkane groups are introduced into the benzoxazine structure. This physically alters the overall polar group distribution density of the molecule. The reduced density of polar groups in the structure decreases dipole orientation polarization, significantly weakening the dynamic response of the dipole moment and reducing the polarization hysteresis effect under high-frequency electric fields. This results in superior high-frequency low dielectric loss and dielectric constant, thus improving dielectric properties. Furthermore, the reaction is staged. The amine compound is first reacted with formaldehyde to ensure that the intermediate product phenolmethyl-NR-hydroxymethylamine completes the oxazine ring-closure reaction with the phenolic hydroxyl group of the phenolic compound, increasing the ring-closure rate and effectively preventing the residue of strongly polar phenolic hydroxyl groups that have not participated in ring-closure dehydration, as well as incomplete polymerization reactions, phase separation, and other abnormalities, thereby improving dielectric insulation.

[0033] Meanwhile, the complex active functional groups of the oxazine ring and unsaturated hydrocarbon groups in the molecular structure can interfere with each other during polymerization at room temperature. Furthermore, this modified benzoxazine resin does not undergo self-polymerization below 60°C, preventing a sudden increase in viscosity or gelation due to self-polymerization. It can be stored for extended periods without curing, exhibiting stable room-temperature storage properties. It has a wide operating window for thermal processing, from its fluid state to the onset of curing temperature. Mixing and stirring can be performed at temperatures ranging from room temperature to 60°C, providing excellent convenience for copper-clad laminate formulation and application. Additionally, the introduction of non-polar alkane groups further enhances its appeal. It has high functional activity per unit molecular weight, i.e., high branching degree, large molecular weight, and a weight average molecular weight greater than 2000. In the copper clad laminate pressing process, it can maintain good fluidity without excessive glue flow, and has good processing performance. Subsequently, under high temperature and / or catalyst conditions, it can undergo oxazine ring opening and unsaturated alkane polymerization reaction to generate an interpenetrating cross-linked ultra-dense three-dimensional network structure. Structurally, it has more C-C cross-links with higher thermal stability than conventional benzoxazine resins, giving the polymerized cured product a higher glass transition temperature, i.e., excellent high heat resistance.

[0034] Therefore, this invention selects alkane-based primary amines and phenolic compounds containing unsaturated alkane groups as raw materials to introduce nonpolar alkane groups into the benzoxazine structure, thereby improving dielectric properties while also exhibiting good heat resistance, storage stability, and processing performance. Furthermore, the phased reaction process addresses the problem of insufficient heat resistance and processing performance in existing benzoxazine resins while improving dielectric properties.

[0035] Specifically, the alkane-based amine compound is one or more of short-chain aliphatic amines, alicyclic polyamines, and monoamine compounds, ensuring that the resulting modified benzoxazine resin has a higher degree of functional branching, thereby exhibiting better heat resistance, better dielectric properties, and better processing performance, enabling its industrial application in high-frequency and high-speed electronic copper-clad laminates.

[0036] Specifically, in step S1, the added formaldehyde can be an aqueous formaldehyde solution or a solid paraformaldehyde powder.

[0037] It is worth noting that the molar ratio of the added alkane-amine type compound to the phenolic type compound is based on a 1:1 molar ratio of the amine group in the alkane-amine type compound to the phenolic hydroxyl group in the phenolic type compound.

[0038] Preferably, the alkane-amine type compound is a diamine type compound and / or the phenolic type compound containing an unsaturated hydrocarbon group is a bisphenol type compound.

[0039] Specifically, diamine compounds or bisphenol compounds can form polycyclic structures after completing the ring-closing reaction, and can continue to undergo prepolymerization and chain extension polymerization after the ring-closing reaction, exhibiting a higher degree of branching.

[0040] Preferably, in step S1, the temperature is raised to 60-90°C and maintained for 0.5-2 hours.

[0041] In step S2, the temperature is raised to 70-100℃ and maintained for 2-5 hours.

[0042] Specifically, the active hydrogen in the unreacted primary amine and / or secondary amine groups undergoes a dehydration condensation side reaction with the intermediate phenol methyl-NR-hydroxymethylamine, preventing phenol methyl-NR-hydroxymethylamine from completing the oxazine ring-closure reaction with the phenolic hydroxyl group. This significantly reduces the ring-closure rate and leaves a large amount of highly polar phenolic hydroxyl groups that did not participate in the ring-closure dehydration, affecting the dielectric insulation performance. Through steps S1 and S2, and by limiting the reaction temperature and time, the raw materials are ensured to undergo dehydration condensation via the Mannich reaction to complete the benzoxazine ring closure, resulting in a higher ring-closure rate, lower highly polar phenolic hydroxyl residue, and improved dielectric insulation.

[0043] In step S1, limiting the temperature helps control the reaction rate, avoid over-reaction and the formation of byproducts, and form a stable dihydroxymethyl tertiary amine compound.

[0044] Preferably, the carbon chain length of the short aliphatic chain amine is C1-C4.

[0045] Specifically, the carbon chain length of the short aliphatic chain is limited to C1-C4 to ensure excellent heat resistance of the resin and prevent a serious reduction in heat resistance due to the addition of groups with excessively long carbon chains.

[0046] Preferably, the short-chain aliphatic amine is ethylenediamine, propylenediamine, butanediamine, methylamine, ethylamine, propylamine, or allylamine.

[0047] Preferably, the alicyclic polyamine is cyclohexanediamine, cyclopentanediamine, 4,4-diaminodicyclohexylmethane, cyclopropylamine, cyclopentaneamine, cyclohexylamine, cyclohexanedimethylamine, or cyclopentanedimethylamine.

[0048] Specifically, alkane-based primary amines are selected, and the above-mentioned alkane-based amine compounds are limited to ensure the introduction of non-polar alkane groups. This satisfies the requirements of high frequency, low dielectric loss, and dielectric constant, while also exhibiting good heat resistance and processability.

[0049] Preferably, the unsaturated hydrocarbon phenolic compound is an allyl-substituted polyphenolic compound or an unsaturated hydrocarbon-substituted monophenolic compound.

[0050] Specifically, allyl-substituted polyphenolic compounds can be allyl bisphenol A, allyl bisphenol F, allyl bisphenol S, and allyl 4,4-biphenyl; unsaturated hydrocarbon-substituted monophenolic compounds can be allylphenol, 2-methoxy-4-vinylphenol, p-hydroxystyrene, and ethynylphenol.

[0051] The raw materials of this invention contain bisphenolic compounds and / or diamine compounds with unsaturated groups, and after the ring-closing reaction is completed, a prepolymerization and chain extension polymerization reaction is carried out. Its polycyclic structure can have a higher degree of branching and better heat resistance.

[0052] Preferably, in step S1, the organic solvent is a polar or non-polar solvent with a boiling point not higher than 170°C.

[0053] In step S3, small molecule impurities and byproducts are removed under negative pressure at 100-170℃ for 1-6 hours.

[0054] Specifically, the organic solvent can be toluene, xylene, n-butanol, methyl ethyl ketone, MIBK, DMF, or cyclohexanone. By removing small molecule impurities and byproducts under negative pressure, the purity of the final product is improved, the number of highly polar phenolic hydroxyl groups is further reduced, performance is improved, the ring-closing reaction of the benzoxazine ring is completed, and a stable resin structure is formed.

[0055] Meanwhile, the boiling point of the organic solvent is no higher than 170℃, which is compatible with the temperature requirements for the negative pressure removal of small molecule impurities and by-products.

[0056] A modified benzoxazine resin is prepared by the above-described method for preparing a modified benzoxazine resin, wherein the benzoxazine structure of the modified benzoxazine resin contains at least one unsaturated hydrocarbon group.

[0057] Specifically, the modified benzoxazine resin has at least one unsaturated hydrocarbon group in its benzoxazine structure, ensuring that the modified benzoxazine resin has a composite active functional group of unsaturated hydrocarbon groups, thereby ensuring that the resin has excellent dielectric properties while also having good processability and heat resistance.

[0058] Preferably, the modified benzoxazine resin has a weight-average molecular weight greater than 2000.

[0059] Specifically, the modified benzoxazine resin has a weight-average molecular weight greater than 2000, which can maintain good fluidity in the copper clad laminate pressing process without causing excessive resin flow. It is suitable for the copper clad laminate matrix resin bonding and pressing process and has good processing performance.

[0060] The application of any one of the modified benzoxazine resins as a circuit dielectric material in high-frequency, high-speed electronic copper-clad laminates.

[0061] Specifically, copper clad laminates are divided into traditional types and high-frequency / high-speed types. High-frequency / high-speed copper clad laminates typically refer to boards with a loss factor (Df) ≤ 0.01 and a dielectric constant (Dk) ≤ 4.5. This modified benzoxazine resin has the characteristics of low dielectric constant and low dielectric loss. As a circuit dielectric material, it can meet the signal transmission requirements of highly integrated circuits in high-end fields. At the same time, this modified benzoxazine resin has a wide thermal processing window, which can maintain good fluidity in the high-frequency / high-speed copper clad laminate pressing process without causing excessive resin flow. Therefore, it can be industrially applied to high-frequency / high-speed electronic copper clad laminates, which have good processing performance while meeting the needs of high-end fields to reduce interconnect delay, power consumption, and crosstalk.

[0062] The technical solution of the present invention will be further illustrated below through specific embodiments.

[0063] Example group

[0064] Example 1

[0065] S1. In a reactor equipped with a stirrer, thermometer, condenser and water separator, add 1 mol of 4,4-diaminodicyclohexylmethane and 4.1 mol of paraformaldehyde, then add 50% of the total mass of the mixture (the sum of alkane-amine type compound, phenol type compound containing unsaturated hydrocarbon groups and paraformaldehyde) of toluene solvent, stir evenly, raise the temperature to 70℃ and keep it at that temperature for 1 hour to complete the first stage of reaction;

[0066] S2. Cool down to 40℃, add 2 mol of o-allylphenol, heat up to 95℃ and keep warm for 3 hours to complete the second stage of reaction;

[0067] S3. Heat to 160℃, remove toluene solvent, small molecule impurities and by-products under negative pressure for 2 hours, condense and reflux to water separator through condenser, and then release toluene solvent, small molecule impurities and by-products from water separator to obtain modified benzoxazine resin.

[0068] Example 2

[0069] S1. In a reactor equipped with a stirrer, thermometer, condenser and water separator, add 1 mol of 4,4-diaminodicyclohexylmethane and 4.3 mol of paraformaldehyde, then add 100% toluene solvent of the total mass of the mixture (the sum of alkane-amine type compound, phenol type compound containing unsaturated hydrocarbon groups and paraformaldehyde), stir evenly, raise the temperature to 75℃ and keep it at that temperature for 0.5h to complete the first stage of reaction;

[0070] S2. Cool down to 40℃, add 0.8 mol of diallyl bisphenol A and 0.4 mol of o-allyl phenol, heat up to 90℃ and keep warm for 3.5 h to complete the second stage reaction;

[0071] S3. Heat to 140℃ and remove toluene solvent, small molecule impurities and by-products under negative pressure for 3 hours. The residue is condensed and refluxed to the water separator through the condenser. The water separator then releases toluene solvent, small molecule impurities and by-products to obtain modified benzoxazine resin.

[0072] Example 3

[0073] S1. In a reactor equipped with a stirrer, thermometer, condenser and water separator, add 0.4 mol of allylamine, 0.8 mol of 4,4-diaminodicyclohexylmethane and 4.6 mol of paraformaldehyde, then add 50% of the total mass of the mixture (the sum of alkane-amine type compound, phenol type compound containing unsaturated hydrocarbon groups and paraformaldehyde) of toluene solvent, stir evenly, raise the temperature to 80℃ and keep it at 1.5h to complete the first stage of reaction;

[0074] S2. Cool down to 40℃, add 1 mol of diallyl bisphenol A, heat up to 85℃ and keep warm for 4 hours to complete the second stage of reaction;

[0075] S3. Heat to 130℃ and remove toluene solvent, small molecule impurities and byproducts under negative pressure for 4 hours. The residue is condensed and refluxed to the water separator through the condenser. The water separator then releases toluene solvent, small molecule impurities and byproducts to obtain modified benzoxazine resin.

[0076] Example 4

[0077] S1. In a reactor equipped with a stirrer, thermometer, condenser and water separator, add 0.4 mol of allylamine, 0.8 mol of 4,4-diaminodicyclohexylmethane and 4.1 mol of paraformaldehyde, then add 50% of the total mass of the mixture (the sum of alkane-amine type compound, phenol type compound containing unsaturated hydrocarbon groups and paraformaldehyde) of toluene solvent, stir evenly, raise the temperature to 85℃ and keep it at that temperature for 2 hours to complete the first stage of reaction;

[0078] S2. Cool down to 40℃, add 0.8 mol of diallyl bisphenol A and 0.4 mol of o-allyl phenol, heat up to 80℃ and keep warm for 4.5 h to complete the second stage reaction;

[0079] S3. Heat to 120℃ and remove toluene solvent, small molecule impurities and by-products under negative pressure for 5 hours. The residue is condensed and refluxed to the water separator through the condenser. The water separator then releases toluene solvent, small molecule impurities and by-products to obtain modified benzoxazine resin.

[0080] Example 5

[0081] S1. In a reactor equipped with a stirrer, thermometer, condenser and water separator, add 1 mol of allylamine and 4.1 mol of paraformaldehyde, then add 50% of the total mass of the mixture (the sum of alkane-amine type compound, phenol type compound containing unsaturated hydrocarbon groups and paraformaldehyde) of toluene solvent, stir evenly, raise the temperature to 70℃ and keep it at that temperature for 1 hour to complete the first stage of reaction;

[0082] S2. Cool down to 40℃, add 1 mol of o-allylphenol, heat up to 95℃ and keep warm for 3 hours to complete the second stage of reaction;

[0083] S3. Heat to 160℃, remove toluene solvent, small molecule impurities and by-products under negative pressure for 2 hours, condense and reflux to water separator through condenser, and then release toluene solvent, small molecule impurities and by-products from water separator to obtain modified benzoxazine resin.

[0084] Comparative group

[0085] Comparative Example 1

[0086] Compared with Example 1, the difference in Comparative Example 1 is that the added alkane-amine compound is 2 mol of diaminodiphenylmethane.

[0087] Comparative Example 2

[0088] Compared to Example 1, Comparative Example 2 differs in that the added alkane-amine compound is 2 mol of allylamine, and the added phenolic compound is 1 mol of bisphenol A. Furthermore, in step S3, the temperature is raised to 100°C, and the sample is removed under negative pressure for 1 hour.

[0089] Comparative Example 3

[0090] S1. In a reactor equipped with a stirrer, thermometer, condenser and water separator, add 1 mol of allylamine and 1 mol of o-allylphenol, then add 50% of the total mass of toluene solvent, heat to 40°C and keep warm for 2 hours.

[0091] S2, add 2.13 mol of paraformaldehyde, heat to 70℃ and react for 2 hours;

[0092] S3. Heat to 100℃ and apply negative pressure for 2 hours to remove toluene solvent, small molecule impurities and byproducts. The residue is condensed and refluxed to the water separator through the condenser. The water separator then releases toluene solvent, small molecule impurities and byproducts to obtain benzoxazine resin.

[0093] The benzoxazine resins obtained in the above-described example groups and comparative example groups were tested. The specific test items and methods are as follows:

[0094] (1) Weight average molecular weight (Mw): 0.01 g of the sample to be tested was weighed and dissolved in 10 mL of tetrahydrofuran. The test was performed using a Waters gel chromatography (GPC) system. The chromatographic columns were Agilent MIXEDD column and shodex KF802 column used in series. The mobile phase was tetrahydrofuran and the flow rate was 1 mL / min.

[0095] (2) Hydroxyl Equivalent (OHEW): Prepare a mixture of 7.8 mL acetic anhydride and 35 mL pyridine. Mix 5 mL of the mixture with 1 g of the test sample and react at 160 °C for 1 h. Add 1-1.5 mL of distilled water, react for 15 min, cool, and dilute with 10 mL tetrahydrofuran and 5 mL acetone. Titrate the test sample solution and the blank control group with 0.5 M KOH solution using potentiometric titration. The potentiometric measuring instrument was a Wantong 888titrando device, and the electrode was a Wantong 6.0229.100 Solvotrode device. The blank control group was without the test sample. Substitute the measured values ​​of the test sample solution and the blank control group into the following formula to calculate the hydroxyl equivalent:

[0096] OHvalue (KOH mg / g) = 28.05 × (BV) × F / mass of the sample to be tested

[0097] Hydroxyl equivalent (g / eq) = 26110 / OH value

[0098] In the formula, B is the measured value of the blank control solution, V is the measured value of the sample solution, and F is the concentration (mol / L) of the titrated KOH (EtOH) solution.

[0099] (3) Gel time (GT): The test shall be conducted in accordance with Clause 4.14 of GB / T 15022-2007.

[0100] Application performance sample preparation method: Weigh 10g of resin product from each example group and comparative example group, grind it, dissolve it in toluene, and then pour it into a polytetrafluoroethylene flat mold for gradient temperature curing. The temperature program is: 150℃*1h, 180℃*1h, 200℃*2h, 220℃*2h, to obtain a reddish-brown block solid.

[0101] (4) Glass transition temperature (Tg): Determined according to the DSC method specified in 2.4.25 of IPC-TM-650.

[0102] (5) Thermal decomposition temperature (Td): Tested using TGA according to IEC61189-2-807:2021 standard.

[0103] (6) Dielectric constant (Dk): The dielectric constant at 10 GHz was determined using the plate method according to section 2.5.5.9 of IPC-TM-650.

[0104] (7) Dielectric loss factor tangent (Df): The dielectric loss factor tangent at 10 GHz was determined using the plate method according to section 2.5.5.9 of IPC-TM-650.

[0105] The specific test results are shown in Table 1:

[0106] Table 1

[0107]

[0108]

[0109] As shown in Table 1, the benzoxazine resins obtained in Examples 1-5 have a weight-average molecular weight greater than 2000 and a gel time between 4.7 and 7.5 min, maintaining good fluidity without excessive flow. Furthermore, after storage at 60°C for 6 months, their weight-average molecular weight and gel time show little change, indicating good storage stability. Simultaneously, their glass transition temperature is above 200°C, dielectric constant is between 3.06 and 3.45, dielectric loss factor tangent is between 0.0043 and 0.0052, and thermal decomposition temperature is between 379 and 418°C. This demonstrates that the benzoxazine resins obtained in Examples 1-5 possess a high glass transition temperature, maintaining high mechanical strength and thermal stability even at higher temperatures. They also exhibit low dielectric constant and dielectric loss factor tangent values, making them suitable for applications requiring high efficiency and low loss. Furthermore, their high thermal decomposition temperature indicates high thermal stability, allowing them to withstand higher temperatures without decomposition. In Example 5, the raw materials used are not diamine and bisphenol structures. Their dielectric constant and dielectric loss factor tangent are higher than those of Examples 1-4, and their branching degree is not as high as that of Examples 1-4. After being stored at 60°C for 6 months, the change in weight-average molecular weight is greater than that of Examples 1-4, meaning that the storage stability is not as good as that of Examples 1-4.

[0110] The difference between Comparative Example 1 and Example 1 is that it does not use any of the following compounds: short aliphatic chain amines, alicyclic polyamines, or monoamine compounds. The difference between Comparative Example 2 and Example 1 is that it does not use phenolic compounds containing unsaturated hydrocarbon groups. The gel time is shorter, the processing performance is not as good as that of the Example group, and the dielectric constant and dielectric loss factor tangent are higher than those of the Example group. The heat resistance is insufficient, which cannot meet the requirements for industrial application in high-frequency and high-speed electronic copper-clad laminates, and cannot meet the application requirements of highly integrated circuit dielectric materials.

[0111] The difference between Comparative Example 3 and the Example Group is that it is not the segmented reaction proposed in this invention, that is, it is not the step of reacting amine compounds and formaldehyde at the corresponding temperature, and then heating the system to 4050°C after adding paraformaldehyde and allowing it to rise naturally. When there is too much material, the exothermic rise is too high and the temperature is easily out of control, posing a serious production safety risk. When there is too little material, the temperature rise is too slow. In step S2, at a low temperature of no more than 70°C, the active hydrogen in the unreacted primary amine group and / or secondary amine group will undergo a dehydration condensation side reaction with the intermediate product phenol methyl-NR-hydroxymethylamine. This causes phenol methyl-NR-hydroxymethylamine to be unable to complete the oxazine ring-closure reaction with the phenolic hydroxyl group, greatly reducing the ring-closure rate. Therefore, there will be more strongly polar phenolic hydroxyl groups that have not participated in the ring-closure dehydration, affecting the dielectric insulation performance. As can be seen from Table 1, Comparative Example 3 has a very low weight-average molecular weight, poor heat resistance, and higher dielectric constant and dielectric loss factor tangent value compared with the Example Group.

[0112] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0113] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. 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 all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for preparing a modified benzoxazine resin, characterized in that, Includes the following steps: S1, First stage reaction: Stir the alkane-amine compound, formaldehyde and organic solvent evenly, heat to 60-90℃ and keep the temperature for 0.5-2h; The alkane-based amine compound is one or more of short-chain aliphatic amines, alicyclic polyamines, and monoamine compounds; S2, Second stage reaction: Add a phenolic compound containing an unsaturated hydrocarbon group, heat to 70-100℃ and keep warm for 2-5 hours; S3. Increase the temperature and remove small molecule impurities and byproducts under negative pressure to obtain modified benzoxazine resin; Wherein, the phenolic compound containing an unsaturated hydrocarbon group is a bisphenol compound and / or the alkane-amine compound is a diamine compound.

2. The method for preparing a modified benzoxazine resin according to claim 1, characterized in that: The carbon chain length of the short aliphatic chain amine is C1-C4.

3. The method for preparing a modified benzoxazine resin according to claim 1, characterized in that: The alicyclic polyamine is cyclohexanediamine, cyclopentanediamine, 4,4-diaminodicyclohexylmethane, cyclopropylamine, cyclopentaneamine, cyclohexylamine, cyclohexanedimethylamine, or cyclopentanedimethylamine.

4. The method for preparing a modified benzoxazine resin according to claim 1, characterized in that: The unsaturated hydrocarbon phenolic compounds are allyl-substituted polyphenolic compounds or unsaturated hydrocarbon-substituted monophenolic compounds.

5. The method for preparing a modified benzoxazine resin according to claim 1, characterized in that: In step S1, the organic solvent is a polar or non-polar solvent with a boiling point not higher than 170°C. In step S3, small molecule impurities and byproducts are removed under negative pressure at 100-170℃ for 1-6 hours.

6. A modified benzoxazine resin, characterized in that, The modified benzoxazine resin is prepared by any one of the preparation methods of claims 1-5, wherein the modified benzoxazine resin has at least one unsaturated hydrocarbon group in its benzoxazine structure.

7. The modified benzoxazine resin according to claim 6, characterized in that: The modified benzoxazine resin has a weight-average molecular weight greater than 2000.

8. The application of the modified benzoxazine resin according to any one of claims 6-7 as a circuit dielectric material in high-frequency and high-speed electronic copper-clad laminates.

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