Modified benzoxazine resin as well as preparation method and application thereof

Abstract

The invention relates to modified benzoxazine resin as well as a preparation method and application thereof. The structural formula of the modified benzoxazine resin is as shown in formula (1), in the formula (1), n is 0-4,-R1,-R2 and-R3 are independently selected from hydrogen atoms or alkyl groups,-R4 is selected from aliphatic alkenyl groups or aromatic alkenyl groups, and the alkenyl groups are located at the end parts of main chains in the-R4; the double bond equivalent of the modified benzoxazine resin is 400 to 800. The modified benzoxazine resin provided by the invention is relatively high in crosslinking density and curing degree in a resin composition, the prepared circuit substrate has excellent heat resistance and dielectric property, meanwhile, the dielectric property is not easy to degrade due to moisture absorption, and the prepared printed circuit board can meet the use requirements of special scenes.

Description

Technical Field

[0001] The present invention relates to the technical field of the electronics industry, and particularly to a modified benzoxazine resin, a preparation method thereof, and an application thereof. Background Art

[0002] With the rapid development of information technology, the usage environment of electronic devices is more extensive. While being efficient in meeting information exchange, processing, and transmission, it is also necessary to ensure the stability of signal transmission speed. Therefore, it is required that the circuit board not only has high dielectric properties, but also has high heat resistance and low moisture absorption degradation ability. Summary of the Invention

[0003] Based on this, in view of the above problems, it is necessary to provide a modified benzoxazine resin, a preparation method thereof, and an application thereof. The circuit board prepared from the modified benzoxazine resin provided by the present invention has excellent heat resistance and dielectric properties. At the same time, its dielectric properties are not easily deteriorated due to moisture absorption, and the printed circuit board prepared therefrom can meet the usage requirements of special scenarios.

[0004] A modified benzoxazine resin has a structural formula as shown in formula (1),

[0005]

[0006] In formula (1), n is 0 to 4, -R1, -R2, and -R3 are each independently selected from a hydrogen atom or an alkyl group, and -R4 is selected from an aliphatic alkenyl group or an aromatic alkenyl group, wherein the alkenyl group is located at the end of the main chain in -R4; the double bond equivalent of the alkenyl group in the modified benzoxazine resin is 400 to 800.

[0007] Preferably, -R1, -R2, and -R3 are each independently selected from a hydrogen atom or a C1 - C 10 alkyl group, and -R4 is selected from a C2 - C8 aliphatic alkenyl group or a C6 - C 13 aromatic alkenyl group, wherein the alkenyl group is located at the end of the main chain in -R4.

[0008] In one embodiment, when -R4 is selected from an aromatic alkenyl group, in -R4, the main chain containing the alkenyl group is located at the meta - position or para - position of any benzene ring.

[0009] In one embodiment, -R4 is selected from

[0010] Or

[0011]

[0012] In one embodiment, the hydroxyl equivalent of the modified benzoxazine resin is 350 to 1000;

[0013] and / or, the softening point of the modified benzoxazine resin is 60°C to 90°C;

[0014] and / or, the weight-average molecular weight of the modified benzoxazine resin is 850 to 1600;

[0015] and / or, the gelation time of the modified benzoxazine resin at 210°C is 300 s to 900 s.

[0016] For the modified benzoxazine resin of the invention, first, the alkenyl group is located at the end position of the main chain where the tertiary amine group is located in the modified benzoxazine resin. The electron-rich alkenyl group and the electron-donating tertiary amine group can stabilize cations, promoting the ring-opening polymerization reaction of the modified benzoxazine resin in the resin composition. Moreover, the modified benzoxazine resin has a specific double bond equivalent, which can improve the heat resistance of the circuit board prepared therefrom and the moisture absorption deterioration of the dielectric properties; second, the modified benzoxazine resin has a monophenol structure. The steric hindrance and molecular structure of the monophenol structure are small, and it has the advantages of low viscosity after melting, low curing temperature and good toughness, which can improve the heat resistance of the modified benzoxazine resin, and can reduce the softening point and rigidity of the modified benzoxazine resin, effectively promoting the cross-linking reaction of the double bonds in the modified benzoxazine resin in the resin composition; third, the modified benzoxazine resin has a dicyclopentadiene ring structure with extremely low polarity, making the dielectric properties of the modified benzoxazine resin and the circuit board prepared therefrom very excellent.

[0017] A preparation method of the modified benzoxazine resin as described above, comprising the following steps:

[0018] React dicyclopentadiene with a monophenol compound under the action of a catalyst to obtain a dicyclopentadiene-based monophenol compound;

[0019] Mix and react the dicyclopentadiene-based monophenol compound, an aldehyde compound and a primary amine compound to obtain the modified benzoxazine resin;

[0020] Among them, the structural formula of the primary amine compound is as shown in formula (2), In formula (2), -R4 is selected from an aliphatic alkenyl group or an aromatic alkenyl group, and the alkenyl group is located at the end of the main chain in -R4.

[0021] In one embodiment, the double bond equivalent of the alkenyl group in the primary amine compound is 50 to 220;

[0022] and / or, the acidity coefficient pKa of the primary amine compound is 4 to 9.

[0023] In one embodiment, the molecular weight of the dicyclopentadiene-based monophenol compound is 650 to 1300.

[0024] In one embodiment, the molar ratio of the dicyclopentadiene-based monophenol compound, the aldehyde compound, and the primary amine compound is 1:(1.9 - 2.2):(0.9 - 1.1).

[0025] A resin composition comprising 50 to 100 parts by weight of a resin and 100 parts by weight of the modified benzoxazine resin as described above.

[0026] The preparation method provided by the present invention introduces an alkene group into the structure of the modified benzoxazine resin through a double-bond primary amine compound with specific double-bond equivalent and position. The reaction of the alkene group is relatively easy, and explosive polymerization can be avoided. At the same time, since the electron-rich alkene group and the electron-donating tertiary amine group can stabilize cations, it is beneficial to the ring-opening polymerization reaction of the modified benzoxazine resin in the resin composition, improving the crosslinking density and curing degree of the resin composition.

[0027] A prepreg made from the resin composition as described above.

[0028] A circuit board, the circuit board comprising a dielectric layer and a conductive layer provided on at least one surface of the dielectric layer, wherein the dielectric layer is formed by pressing one or at least two laminated prepregs as described above.

[0029] A printed circuit board, the printed circuit board comprising the circuit board as described above.

[0030] Compared with the prior art, the resin composition containing the modified benzoxazine resin of the present invention has a significantly higher crosslinking density and curing degree, fewer unreacted hydrophilic groups, and can reduce the water molecules hydrogen-bonded to it. Therefore, the circuit board prepared has excellent heat resistance and dielectric properties, and its dielectric properties are not easily deteriorated due to moisture absorption. The printed circuit board prepared can meet the use requirements of special scenarios. Detailed Description

[0031] To facilitate the understanding of the present invention, the present invention will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. On the contrary, the purpose of providing these embodiments or examples is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this invention belongs. The terms used in the specification of this invention are only for the purpose of describing specific embodiments or examples, and are not intended to limit the present invention. The optional scope of the term "and / or" used herein includes any one of two or more related listed items, and also includes any and all combinations of the related listed items. The any and all combinations include any two related listed items, any more related listed items, or the combination of all related listed items.

[0033] The present invention provides a modified benzoxazine resin, and its structural formula is shown in formula (1),

[0034]

[0035] In formula (1), n is 0 to 4, -R1, -R2 and -R3 are each independently selected from a hydrogen atom or an alkyl group, and -R4 is selected from an aliphatic alkenyl group or an aromatic alkenyl group, wherein the alkenyl group is located at the end of the main chain in -R4; the double bond equivalent of the alkenyl group in the modified benzoxazine resin is 400 to 800.

[0036] For the above-mentioned modified benzoxazine resin, first, the alkenyl group is located at the end group position of the main chain where the tertiary amine group is located in the modified benzoxazine resin. The electron-rich alkenyl group and the electron-donating tertiary amine group can stabilize cations and promote the ring-opening polymerization reaction of the modified benzoxazine resin in the resin composition. Moreover, the alkenyl group in the modified benzoxazine resin has a specific double bond equivalent, which can improve the high heat resistance of the circuit board prepared therefrom and the moisture absorption deterioration of the dielectric properties; second, the modified benzoxazine resin has a monophenol structure. The steric hindrance and molecular structure of the monophenol structure are small, and it has the advantages of low viscosity after melting, low curing temperature and good toughness, which can improve the heat resistance of the modified benzoxazine resin and can reduce the softening point and rigidity of the modified benzoxazine resin, effectively promoting the cross-linking reaction of the double bonds in the modified benzoxazine resin in the resin composition; third, the modified benzoxazine resin has a dicyclopentadiene ring structure with extremely low polarity, making the dielectric properties of the modified benzoxazine resin and the circuit board prepared therefrom very excellent.

[0037] Therefore, the resin composition containing the modified benzoxazine resin of the present invention has a significantly high crosslinking density and curing degree, and there are fewer unreacted hydrophilic groups, which can reduce the water molecules hydrogen-bonded thereto. Thus, the circuit board prepared has excellent heat resistance and dielectric properties, and the dielectric properties are not easily deteriorated due to moisture absorption. The printed circuit board prepared therefrom can meet the use requirements of special scenarios.

[0038] In one embodiment, -R1, -R2 and -R3 are each independently selected from a hydrogen atom or C1-C10 The alkyl group, -R4 is selected from a C2-C8 aliphatic alkenyl group or a C6-C 13 aromatic alkenyl group, wherein the alkenyl group is located at the end of the main chain in the -R4.

[0039] In one embodiment, when the -R4 is selected from an aromatic alkenyl group, in the -R4, the main chain containing the alkenyl group is located at the meta or para position of any benzene ring. At this time, the double bond is less affected by steric hindrance, which is beneficial to the cross-linking reaction of the double bond, thereby improving the moisture absorption deterioration of the dielectric properties while enhancing the heat resistance of the circuit board made of the modified benzoxazine resin.

[0040] Preferably, the -R4 is selected from

[0041] or

[0042] In one embodiment, the hydroxyl equivalent of the modified benzoxazine resin is 350-1000, which can prevent excessive hydroxyl residues in the circuit board from forming hydrogen bonds with water molecules, and is beneficial to improving the moisture absorption deterioration of its dielectric properties.

[0043] In one embodiment, the softening point of the modified benzoxazine resin is 60°C to 90°C, which improves the reaction efficiency of the alkenyl group in the modified benzoxazine resin in the resin composition, enhances its cross-linking and curing degree, thereby improving the heat resistance of the circuit board made and improving the moisture absorption deterioration of its dielectric properties.

[0044] Preferably, the softening point of the modified benzoxazine resin is 75°C to 80°C.

[0045] In one embodiment, the weight average molecular weight of the modified benzoxazine resin is 850-1600. The molecular weight affects the reaction rate and diffusion efficiency of molecular motion. At this time, the reaction efficiency of the alkenyl group in the modified benzoxazine resin in the resin composition is relatively high, enhancing its cross-linking and curing degree, thereby improving the heat resistance of the circuit board made and improving the moisture absorption deterioration of its dielectric properties.

[0046] In one embodiment, the gelation time of the modified benzoxazine resin at 210°C is 300s to 900s. At this time, the self-polymerization reaction of the modified benzoxazine resin itself is relatively slow, which is beneficial to the reaction of the alkenyl group in the modified benzoxazine resin in the resin composition, enhancing its cross-linking and curing degree, thereby improving the heat resistance of the circuit board made and improving the moisture absorption deterioration of its dielectric properties.

[0047] The present invention also provides a preparation method of the modified benzoxazine resin as described above, including the following steps:

[0048] S1. React dicyclopentadiene with a monophenolic compound under the action of a catalyst to obtain a dicyclopentadiene-based monophenolic compound;

[0049] S2. Mix and react the dicyclopentadiene-based monophenolic compound, an aldehyde compound, and a primary amine compound to obtain the modified benzoxazine resin;

[0050] Among them, the structural formula of the primary amine compound is as shown in formula (2), In formula (2), -R4 is selected from an aliphatic alkenyl group or an aromatic alkenyl group, and the alkenyl group is located at the end of the main chain in -R4; the double bond equivalent of the alkenyl group in the primary amine compound is 50-220.

[0051] In step S1, the structural formula of the monophenolic compound used is as shown in formula (3), The steric hindrance and molecular structure of the monophenol structure in the dicyclopentadiene-based monophenolic compound are small, having the advantages of low viscosity after melting, low curing temperature, and good toughness, which can improve the heat resistance of the modified benzoxazine resin, and can reduce the softening point and rigidity of the modified benzoxazine resin, effectively promoting the cross-linking reaction of the double bond in the modified benzoxazine resin in the resin composition; in addition, the dicyclopentadiene ring structure in the dicyclopentadiene-based monophenolic compound has a relatively low polarity, so that the dielectric properties of the obtained modified benzoxazine resin and the circuit board are very excellent.

[0052] Specifically, the structural formula of the dicyclopentadiene-based monophenolic compound is as shown in formula (4). In formula (4), m is 0-4, and -R1, -R2, and -R3 are each independently selected from a hydrogen atom or an alkyl group,

[0053]

[0054] In one embodiment, the molecular weight of the dicyclopentadiene-based monophenolic compound is 650-1300, which can effectively control the hydroxyl equivalent of the modified benzoxazine resin and is beneficial to improving the moisture absorption deterioration of the dielectric properties of the obtained circuit board.

[0055] In one embodiment, the catalyst is selected from at least one of p-toluenesulfonic acid, trifluoromethanesulfonic acid, boron trifluoride, ferric trichloride, anhydrous aluminum trichloride, and concentrated sulfuric acid, and the mass of the catalyst accounts for 0.5%-1% of the mass of the monophenolic compound.

[0056] In one embodiment, the molar ratio of the dicyclopentadiene to the monophenolic compound is 1:1-2:1.

[0057] In one embodiment, the reaction temperature of the dicyclopentadiene and the monophenolic compound under the action of the catalyst is 80°C-120°C.

[0058] In step S2, an alkenyl group is introduced into the structure of the modified benzoxazine resin through a double-bond primary amine compound with a specific double-bond position. The double-bond reaction is relatively easy, and explosive polymerization can be avoided. At the same time, since the electron-rich alkenyl group and the electron-donating tertiary amine group can stabilize cations, it is beneficial to the ring-opening polymerization reaction of the modified benzoxazine resin in the resin composition, and the crosslinking density and curing degree of the resin composition are improved.

[0059] It should be noted that in the preparation method of the present invention, a double-bond primary amine compound rather than a dicyclopentadiene-type double-bond monophenol compound is used to introduce a double bond into the structure of the modified benzoxazine resin. Since the double bond and the hydroxyl group in the dicyclopentadiene-type double-bond monophenol compound are both electron-withdrawing groups, although the solubility of the modified benzoxazine resin can be improved and its heat resistance can be enhanced to a certain extent, the electron-withdrawing group will affect the electronegativity of the molecule and change the reaction process, which may cause other functional groups in the resin composition containing the modified benzoxazine resin to react, resulting in obvious deterioration of the dielectric properties of the prepared circuit board due to moisture absorption.

[0060] In addition, step S2 adopts a one-step synthesis method with a one-time feeding, which has the advantages of a short reaction path and mild reaction conditions, and can avoid excessive side reactions of the alkenyl group in the double-bond primary amine compound during the synthesis process, and prematurely consume the double bond, thereby improving the purity and yield of the modified benzoxazine resin product.

[0061] In one embodiment, the double-bond equivalent of the alkenyl group in the primary amine compound is 50-220, which is beneficial to the ring-opening polymerization reaction of the modified benzoxazine resin in the resin composition and can ensure its heat resistance.

[0062] In one embodiment, the acidity coefficient pKa of the primary amine compound is 4-9. Since the alkenyl group itself is alkaline, the gelation time of the prepared modified benzoxazine resin at 210 °C is prolonged, which is beneficial to the crosslinking reaction of the alkenyl group in the modified benzoxazine resin in the resin composition, improving the crosslinking density and curing degree of the resin composition, thereby achieving the effects of improving the heat resistance of the prepared circuit board and improving the moisture absorption deterioration.

[0063] In one embodiment, the aldehyde compound is selected from aqueous formaldehyde or paraformaldehyde. The paraformaldehyde is a mixture of one or more formaldehydes with a polymerization degree of 10-100, and its added amount in moles is calculated according to the theoretical number of moles of formaldehyde, that is, the number of moles = mass × purity ÷ 30.

[0064] In one embodiment, the molar ratio of the dicyclopentadiene-type monophenol compound, the aldehyde compound, and the primary amine compound is 1:(1.9-2.2):(0.9-1.1), which improves the purity and yield of the modified benzoxazine resin.

[0065] In one embodiment, when the dicyclopentadiene-based monophenol compound, aldehyde compound and primary amine compound are mixed and reacted, the reaction system further includes a polymerization catalyst, and the molar ratio of the polymerization catalyst to the primary amine compound is ≤0.5%, preferably, the molar ratio of the polymerization catalyst to the primary amine compound is 0.3% - 0.4%.

[0066] Specifically, the polymerization catalyst is selected from at least one of cuprous chloride, cuprous oxide, ferric chloride, aluminum chloride and sodium sulfide.

[0067] To increase the reaction rate and degree of the mixed reaction of the dicyclopentadiene-based monophenol compound, aldehyde compound and primary amine compound, the reaction conditions are adjusted to 80°C - 120°C. At the same time, it can prevent the generation of reaction by-products due to too high temperature, thereby improving the purity and yield of the modified benzoxazine resin. Preferably, the reaction temperature is 100°C - 110°C.

[0068] The present invention also provides a resin composition, which includes 50 - 100 parts by weight of a resin and 100 parts by weight of the modified benzoxazine resin as described above. This resin composition has high heat resistance and dielectric properties.

[0069] Specifically, the resin is selected from at least one of epoxy resin, bismaleimide, phosphorus-containing phenolic resin, cyanate ester, active ester and modified polyphenylene ether.

[0070] In one embodiment, based on 100 parts by weight of the modified benzoxazine resin, the resin composition further includes 20 - 150 parts by weight of a filler, and the filler is selected from at least one of silica, aluminum hydroxide, boehmite, composite silica powder and barium sulfate.

[0071] In one embodiment, based on 100 parts by weight of the modified benzoxazine resin, the resin composition further includes 1 - 15 parts by weight of an additive, and the additive is selected from 1 - 10 parts by weight of a curing agent, 1 - 5 parts by weight of a silane coupling agent and 1 - 10 parts by weight of a flame retardant.

[0072] It should be noted that the above additives are all commonly used additives in the industry, and the present invention does not limit them. For example, the curing agent can be 2-methylimidazole, 2,4-dimethylimidazole, peroxide, etc.; the silane coupling agent can be KH550, KH560, KH570, KH792, DL602, DL171, etc.; the flame retardant can be nitrogen-containing flame retardants and phosphorus-containing flame retardants, etc.

[0073] In one embodiment, based on 100 parts by weight of the modified benzoxazine resin, the resin composition further includes 50 to 200 parts by weight of a solvent selected from at least one of methyl ethyl ketone, toluene, propylene glycol methyl ether acetate, N,N-dimethylformamide, and propylene glycol methyl ether.

[0074] The present invention also provides a prepreg made from the resin composition as described above. The resin composition in this prepreg has a relatively high crosslinking density and curing degree, with fewer unreacted hydrophilic groups, and can reduce the water molecules hydrogen-bonded to it.

[0075] Specifically, after mixing the above resin composition evenly, the glass fiber cloth is impregnated in the above resin composition, and after heating in an oven at 170°C to 180°C for 2 minutes to 4 minutes, the prepreg is obtained.

[0076] The present invention also provides a circuit board, which includes a dielectric layer and a conductive layer provided on at least one surface of the dielectric layer. Among them, the dielectric layer is formed by pressing one or at least two laminated prepregs as described above. This circuit board has excellent heat resistance and dielectric properties, and its dielectric properties are not easily deteriorated due to moisture absorption.

[0077] In one embodiment, at least two of the above prepregs are stacked, and one copper foil is added to each outer layer. The circuit board is obtained by pressing at a pressure of 300 psi to 400 psi, a vacuum degree of 71 cmHg to 76 cmHg, and a temperature of 80°C to 220°C for 260 minutes to 300 minutes.

[0078] The present invention also provides a printed circuit board, which includes the circuit board as described above, and the printed circuit board can meet the usage requirements of special scenarios.

[0079] Specifically, the printed circuit board is made from the circuit board through processes such as drilling board, hole finishing, micro-etching, pre-impregnation, activation, acceleration, electroless copper, and copper thickening.

[0080] Hereinafter, the modified benzoxazine resin, its preparation method, and applications will be further described through the following specific examples.

[0081] Example 1

[0082] 1 mol of dicyclopentadiene, 1 mol of phenol monomer (structural formula shown in Formula 3-1), and p-toluenesulfonic acid (with a mass of 0.7% of the phenol monomer) were reacted at 110 °C to produce a dicyclopentadiene-based monophenol compound (structural formula shown in Formula 4-1), with a molecular weight of 772. Then, 1 mol of the dicyclopentadiene-based monophenol compound, 2 mol of paraformaldehyde (Merck SigamaAldrich 8.18715), 1 mol of a double-bond primary amine compound (structural formula shown in Formula 2-1, double-bond equivalent of 120, acidity coefficient of 4.39), and cuprous chloride (with a mass of 0.3% of the double-bond primary amine compound) were reacted at 110 °C to obtain a modified benzoxazine resin.

[0083]

[0084] 100 parts by weight of the modified benzoxazine resin, 50 parts by weight of bismaleimide resin (Dongcai D930), 50 parts by weight of epoxy resin (Shengquan SQCN-700), 3 parts by weight of 2,4-dimethylimidazole, 2 parts by weight of silane coupling agent (KH560), 100 parts by weight of methyl ethyl ketone, and 100 parts by weight of silica were mixed evenly. Then, the fiberglass cloth was impregnated in the above resin composition. After heating in an oven at 180 °C for 3 min, a prepreg was obtained. Two prepregs were stacked, and one copper foil was added to each outer layer. After pressing at 400 psi, a vacuum of 75 cmHg, and 220 °C for 260 min, a circuit board was obtained.

[0085] The modified benzoxazine resin prepared in Example 1 was tested by nuclear magnetic resonance spectroscopy (nuclear magnetic resonance frequency of 300 MHz, solvent of deuterated DMSO, standard of TMS). Its nuclear magnetic data was δ6.00 (s, 4H), δ4.61 (s, 4H), δ5.25 (d, 2H), δ5.76 (d, 2H), δ6.72 (m, 2H). Among them, δ6.00 (s, 4H) belongs to the hydrogen protons on the carbon in -CH2-O- produced after the reaction of amino, hydroxyl, and paraformaldehyde. δ4.61 (s, 4H) belongs to the hydrogen protons on the carbon in -CH2- produced after the reaction of amino and paraformaldehyde.

[0086] δ5.25 (d, 2H), δ5.76 (d, 2H), δ6.72 (m, 2H) belong to the hydrogen protons on the carbon in the terminal -CH=CH2 of the primary amine compound, indicating that the modified benzoxazine resin prepared in Example 1 has the structural formula shown in Formula (1-1).

[0087]

[0088] Example 2

[0089] React 1 mol of dicyclopentadiene with 2 mol of phenol monomer (structural formula as Formula 3-1) and p-toluenesulfonic acid (with a mass of 0.5% of the phenol monomer) at 110 °C to form a dicyclopentadiene-based monophenol compound (structural formula as Formula 4-2), with a molecular weight of 659. Then, react 1 mol of the dicyclopentadiene-based monophenol compound, 2 mol of paraformaldehyde (Merck SigamaAldrich 8.18715), 1 mol of a double-bond primary amine compound (structural formula as Formula 2-1, double-bond equivalent of 120, acidity coefficient of 4.39), and copper chloride (with a mass of 0.3% of the double-bond primary amine compound) at 110 °C to obtain a modified benzoxazine resin. The structural formula of the modified benzoxazine resin is Formula (1-2).

[0090]

[0091] Mix 100 parts by weight of the modified benzoxazine resin, 50 parts by weight of the bismaleimide resin (Dongcai D930), 50 parts by weight of the epoxy resin (Shengquan SQCN-700), 3 parts by weight of 2,4-dimethylimidazole, 2 parts by weight of the silane coupling agent (KH560), 100 parts by weight of methyl ethyl ketone, and 100 parts by weight of silica evenly. Then, immerse the fiberglass cloth in the above resin composition and heat it in an oven at 180 °C for 3 min to obtain a prepreg. Stack 2 prepregs, attach a copper foil to each outer layer, and press them at 400 psi pressure, 75 cmHg vacuum, and 220 °C for 260 min to obtain a circuit board.

[0092] Example 3

[0093] React 1 mol of dicyclopentadiene with 1 mol of phenol monomer (structural formula as Formula 3-1) and p-toluenesulfonic acid (with a mass of 0.9% of the phenol monomer) at 120 °C to form a dicyclopentadiene-based monophenol compound (structural formula as Formula 4-3), with a molecular weight of 1224. Then, react 1 mol of the dicyclopentadiene-based monophenol compound, 2 mol of paraformaldehyde (Merck SigamaAldrich 8.18715), 1 mol of a double-bond primary amine compound (structural formula as Formula 2-1, double-bond equivalent of 120, acidity coefficient of 4.39), and copper chloride (with a mass of 0.5% of the double-bond primary amine compound) at 115 °C to obtain a modified benzoxazine resin. The structural formula of the modified benzoxazine resin is Formula (1-3).

[0094]

[0095] 100 parts by weight of the modified benzoxazine resin, 50 parts by weight of the bismaleimide resin (Dongcai D930), 50 parts by weight of the epoxy resin (Shengquan SQCN-700), 3 parts by weight of 2,4-dimethylimidazole, 2 parts by weight of the silane coupling agent (KH560), 100 parts by weight of methyl ethyl ketone, and 100 parts by weight of silica are mixed evenly. Then, the fiberglass cloth is impregnated in the above resin composition. After heating in an oven at 180 °C for 3 minutes, a prepreg is obtained. Two prepregs are stacked, and one copper foil is added to each outer layer. After pressing at 400 psi pressure, 75 cmHg vacuum, and 220 °C for 260 minutes, a circuit board is obtained.

[0096] Example 4

[0097] 1 mol of dicyclopentadiene, 1 mol of phenol monomer (structural formula as Formula 3-1), and p-toluenesulfonic acid (0.7% of the mass of the phenol monomer) are reacted at 110 °C to generate a dicyclopentadiene-based monophenol compound (structural formula as Formula 4-1) with a molecular weight of 772. Then, 1 mol of the dicyclopentadiene-based monophenol compound, 2.2 mol of aqueous formaldehyde solution (formaldehyde content 37%), 1 mol of a double-bond primary amine compound (structural formula as Formula 2-1, double-bond equivalent 120, acidity coefficient 4.39), and cuprous chloride (0.3% of the mass of the double-bond primary amine compound) are reacted at 110 °C to obtain a modified benzoxazine resin, and the structural formula of the modified benzoxazine resin is Formula (1-4).

[0098]

[0099] 100 parts by weight of the modified benzoxazine resin, 70 parts by weight of the bismaleimide (Hexcel's RTM650), 20 parts by weight of the phosphorus-containing phenolic resin (SHIN-A's LC950), 10 parts by weight of the epoxy resin (Dow's 530A80), 3 parts by weight of 2,4-dimethylimidazole, 2 parts by weight of the silane coupling agent (KH560), 50 parts by weight of toluene, 50 parts by weight of methyl ethyl ketone, and 100 parts by weight of silica are mixed evenly. Then, the fiberglass cloth is impregnated in the above resin composition. After heating in an oven at 180 °C for 3 minutes, a prepreg is obtained. Two prepregs are stacked, and one copper foil is added to each outer layer. After pressing at 400 psi pressure, 75 cmHg vacuum, and 220 °C for 260 minutes, a circuit board is obtained.

[0100] Example 5

[0101] 1 mol of dicyclopentadiene, 1 mol of phenol monomer (structural formula as Formula 3-2), and p-toluenesulfonic acid (with a mass of 0.8% of the phenol monomer) are reacted at 110 °C to produce a dicyclopentadiene-based monophenol compound (structural formula as Formula 4-4), with a molecular weight of 994. Then, 1 mol of the dicyclopentadiene-based monophenol compound, 2 mol of paraformaldehyde (Merck SigamaAldrich 8.18715), 1 mol of a double-bond primary amine compound (structural formula as Formula 2-1, double-bond equivalent of 120, acidity coefficient of 4.39), and copper chloride (with a mass of 0.3% of the double-bond primary amine compound) are reacted at 120 °C to obtain a modified benzoxazine resin, and the structural formula of the modified benzoxazine resin is Formula (1-5).

[0102]

[0103] 100 parts by weight of the modified benzoxazine resin, 50 parts by weight of the bismaleimide resin (Dongcai D930), 50 parts by weight of the epoxy resin (Shengquan SQCN-700), 3 parts by weight of 2,4-dimethylimidazole, 2 parts by weight of the silane coupling agent (KH560), 100 parts by weight of methyl ethyl ketone, and 100 parts by weight of silica are mixed evenly. Then, the glass fiber cloth is impregnated in the above resin composition, and after heating in an oven at 180 °C for 3 min, a prepreg is obtained. Two prepregs are stacked, and one copper foil is added to each outer layer. After pressing at 400 psi pressure, 75 cmHg vacuum, and 220 °C for 260 min, a circuit board is obtained.

[0104] Example 6

[0105] 1 mol of dicyclopentadiene, 1 mol of phenol monomer (structural formula as Formula 3-1), and p-toluenesulfonic acid (with a mass of 0.7% of the phenol monomer) are reacted at 110 °C to produce a dicyclopentadiene-based monophenol compound (structural formula as Formula 4-1), with a molecular weight of 772. Then, 1 mol of the dicyclopentadiene-based monophenol compound, 2 mol of paraformaldehyde (Merck SigamaAldrich 8.18715), 1 mol of a double-bond primary amine compound (structural formula as Formula 2-2, double-bond equivalent of 43, acidity coefficient of 7.6), and copper chloride (with a mass of 0.3% of the double-bond primary amine compound) are reacted at 100 °C to obtain a modified benzoxazine resin, and the structural formula of the modified benzoxazine resin is Formula (1-6).

[0106]

[0107] 100 parts by weight of a modified benzoxazine resin, 50 parts by weight of a bismaleimide resin (Dongcai D930), 50 parts by weight of an epoxy resin (Shengquan SQCN-700), 3 parts by weight of 2,4-dimethylimidazole, 2 parts by weight of a silane coupling agent (KH560), 100 parts by weight of methyl ethyl ketone, and 100 parts by weight of silica are mixed evenly. Then, a glass fiber cloth is impregnated in the above resin composition. After heating in an oven at 180 °C for 3 min, a prepreg is obtained. Two prepregs are stacked, and one copper foil is added to each outer layer. After pressing at 400 psi pressure, 75 cmHg vacuum, and 220 °C for 260 min, a circuit board is obtained.

[0108] Example 7

[0109] 1 mol of dicyclopentadiene, 1 mol of a phenol monomer (structural formula shown in Formula 3-1), and p-toluenesulfonic acid (0.7% of the mass of the phenol monomer) are reacted at 110 °C to form a dicyclopentadiene-based monophenol compound (structural formula shown in Formula 4-1) with a molecular weight of 772. Then, 1 mol of the dicyclopentadiene-based monophenol compound, 2 mol of paraformaldehyde (Merck SigamaAldrich 8.18715), 1 mol of a double-bond primary amine compound (structural formula shown in Formula 2-3, double-bond equivalent 57, acidity coefficient 8.9), and copper chloride (0.3% of the mass of the double-bond primary amine compound) are reacted at 110 °C to obtain a modified benzoxazine resin. The structural formula of the modified benzoxazine resin is shown in Formula (1-7).

[0110]

[0111] 100 parts by weight of a modified benzoxazine resin, 50 parts by weight of a bismaleimide resin (Dongcai D930), 50 parts by weight of an epoxy resin (Shengquan SQCN-700), 3 parts by weight of 2,4-dimethylimidazole, 2 parts by weight of a silane coupling agent (KH560), 100 parts by weight of methyl ethyl ketone, and 100 parts by weight of silica are mixed evenly. Then, a glass fiber cloth is impregnated in the above resin composition. After heating in an oven at 180 °C for 3 min, a prepreg is obtained. Two prepregs are stacked, and one copper foil is added to each outer layer. After pressing at 400 psi pressure, 75 cmHg vacuum, and 220 °C for 260 min, a circuit board is obtained.

[0112] Example 8

[0113] React 1 mol of dicyclopentadiene with 1 mol of phenol monomer (structural formula as Formula 3-1) and p-toluenesulfonic acid (0.7% by mass of the phenol monomer) at 110 °C to produce a dicyclopentadiene-type monophenol compound (structural formula as Formula 4-1), with a molecular weight of 772. Then, react 1 mol of the dicyclopentadiene-type monophenol compound, 2 mol of paraformaldehyde (Merck SigamaAldrich 8.18715), 1 mol of a double-bond primary amine compound (structural formula as Formula 2-4, double-bond equivalent 210, acidity coefficient 6.69), and copper chloride (0.3% by mass of the double-bond primary amine compound) at 110 °C to obtain a modified benzoxazine resin. The structural formula of the modified benzoxazine resin is Formula (1-8).

[0114]

[0115] Mix 100 parts by weight of the modified benzoxazine resin, 50 parts by weight of the bismaleimide resin (Dongcai D930), 50 parts by weight of the epoxy resin (Shengquan SQCN-700), 3 parts by weight of 2,4-dimethylimidazole, 2 parts by weight of the silane coupling agent (KH560), 100 parts by weight of methyl ethyl ketone, and 100 parts by weight of silica evenly. Then, immerse the fiberglass cloth in the above resin composition and heat it in an oven at 180 °C for 3 min to obtain a prepreg. Stack 2 prepregs, attach a copper foil to each outer layer, and press them at 400 psi pressure, 75 cmHg vacuum, and 220 °C for 260 min to obtain a circuit board.

[0116] Example 9

[0117] React 1 mol of dicyclopentadiene with 1 mol of phenol monomer (structural formula as Formula 3-3) and p-toluenesulfonic acid (0.5% by mass of the phenol monomer) at 110 °C to produce a dicyclopentadiene-type monophenol compound (structural formula as Formula 4-5), with a molecular weight of 828. Then, react 1 mol of the dicyclopentadiene-type monophenol compound, 2 mol of paraformaldehyde (Merck SigamaAldrich 8.18715), 1 mol of a double-bond primary amine compound (structural formula as Formula 2-1, double-bond equivalent 120, acidity coefficient 4.39), and copper chloride (0.3% by mass of the double-bond primary amine compound) at 110 °C to obtain a modified benzoxazine resin. The structural formula of the modified benzoxazine resin is Formula (1-9).

[0118]

[0119] 100 parts by weight of the modified benzoxazine resin, 50 parts by weight of the bismaleimide resin (Dongcai D930), 50 parts by weight of the epoxy resin (Shengquan SQCN-700), 3 parts by weight of 2,4-dimethylimidazole, 2 parts by weight of the silane coupling agent (KH560), 100 parts by weight of methyl ethyl ketone, and 100 parts by weight of silicon dioxide were mixed evenly. Then, the glass fiber cloth was impregnated in the above resin composition. After heating in an oven at 180 °C for 3 min, a prepreg was obtained. Two prepregs were stacked, and one copper foil was added to each outer layer. After pressing at 400 psi pressure, 75 cmHg vacuum, and 220 °C for 260 min, a circuit board was obtained.

[0120] Example 10

[0121] 1 mol of dicyclopentadiene, 1 mol of phenol monomer (structural formula as formula 3-4), and p-toluenesulfonic acid (0.7% by mass of the phenol monomer) were reacted at 120 °C to form a dicyclopentadiene-based monophenol compound (structural formula as formula 4-6), with a molecular weight of 1220. Then, 1 mol of the dicyclopentadiene-based monophenol compound, 2 mol of paraformaldehyde (Merck SigamaAldrich 8.18715), 1 mol of a double-bond primary amine compound (structural formula as formula 2-1, double-bond equivalent 120, acidity coefficient 4.39), and copper chloride (0.3% by mass of the double-bond primary amine compound) were reacted at 110 °C to obtain the modified benzoxazine resin, and the structural formula of the modified benzoxazine resin was formula (1-10).

[0122]

[0123] 100 parts by weight of the modified benzoxazine resin, 50 parts by weight of the bismaleimide resin (Dongcai D930), 50 parts by weight of the epoxy resin (Shengquan SQCN-700), 3 parts by weight of 2,4-dimethylimidazole, 2 parts by weight of the silane coupling agent (KH560), 100 parts by weight of methyl ethyl ketone, and 100 parts by weight of silicon dioxide were mixed evenly. Then, the glass fiber cloth was impregnated in the above resin composition. After heating in an oven at 180 °C for 3 min, a prepreg was obtained. Two prepregs were stacked, and one copper foil was added to each outer layer. After pressing at 400 psi pressure, 75 cmHg vacuum, and 220 °C for 260 min, a circuit board was obtained.

[0124] Comparative Example 1

[0125] 1 mol of dicyclopentadiene, 1 mol of bisphenol A, and p-toluenesulfonic acid (0.7% by mass of the phenol monomer) were reacted at 110 °C to produce a dicyclopentadiene-based bisphenol compound (structural formula as Formula 5), with a molecular weight of 1600. Then, 1 mol of the dicyclopentadiene-based bisphenol compound, 2 mol of paraformaldehyde (Merck SigamaAldrich 8.18715), 1 mol of a double-bond primary amine compound (structural formula as Formula 2-1, double-bond equivalent of 120, acidity coefficient of 4.39), and copper chloride (0.3% by mass of the double-bond primary amine compound) were reacted at 110 °C to obtain a modified benzoxazine resin, and the structural formula of the modified benzoxazine resin is Formula (6).

[0126]

[0127] 100 parts by weight of the modified benzoxazine resin, 50 parts by weight of the bismaleimide resin (Dongcai D930), 50 parts by weight of the epoxy resin (Shengquan SQCN-700), 3 parts by weight of 2,4-dimethylimidazole, 2 parts by weight of the silane coupling agent (KH560), 100 parts by weight of methyl ethyl ketone, and 100 parts by weight of silica were mixed evenly. Then, the glass fiber cloth was impregnated in the above resin composition and heated in an oven at 180 °C for 3 min to obtain a prepreg. Two prepregs were stacked, and one copper foil was added to each outer layer. After pressing at 400 psi pressure, 75 cmHg vacuum, and 220 °C for 260 min, a circuit board was obtained.

[0128] Comparative Example 2

[0129] 1 mol of dicyclopentadiene, 1 mol of a phenol monomer (structural formula as Formula 3-1), and p-toluenesulfonic acid (1.0% by mass of the phenol monomer) were reacted at 120 °C to produce a dicyclopentadiene-based monophenol compound (structural formula as Formula 7), with a molecular weight of 1450. Then, 1 mol of the dicyclopentadiene-based monophenol compound, 2 mol of paraformaldehyde (Merck SigamaAldrich 8.18715), 1 mol of a double-bond primary amine compound (structural formula as Formula 2-1, double-bond equivalent of 120, acidity coefficient of 4.39), and copper chloride (0.5% by mass of the double-bond primary amine compound) were reacted at 120 °C to obtain a modified benzoxazine resin, and the structural formula of the modified benzoxazine resin is Formula (8).

[0130]

[0131] After uniformly mixing 100 parts by weight of a modified benzoxazine resin, 50 parts by weight of a bismaleimide resin (Dongcai D930), 50 parts by weight of an epoxy resin (Shengquan SQCN-700), 3 parts by weight of 2,4-dimethylimidazole, 2 parts by weight of a silane coupling agent (KH560), 100 parts by weight of methyl ethyl ketone, and 100 parts by weight of silica, a glass fiber cloth was impregnated in the above resin composition. After heating in an oven at 180 °C for 3 minutes, a prepreg was obtained. Two prepregs were stacked, and one copper foil was added to each outer layer. After pressing at 400 psi pressure, 75 cmHg vacuum, and 220 °C for 260 minutes, a circuit board was obtained.

[0132] Comparative Example 3

[0133] 1 mol of dicyclopentadiene was reacted with 1 mol of phenol monomer (structural formula shown in Formula 3-1) and p-toluenesulfonic acid (0.7% of the mass of the phenol monomer) at 110 °C to form a dicyclopentadiene-based monophenol compound (structural formula shown in Formula 4-1), with a molecular weight of 772. Then, 1 mol of the dicyclopentadiene-based monophenol compound, 2 mol of paraformaldehyde (Merck SigamaAldrich 8.18715), 1 mol of a double-bond primary amine compound (structural formula shown in Formula 2-1, double-bond equivalent 148, acidity coefficient 5.15), and copper chloride (0.3% of the mass of the double-bond primary amine compound) were reacted at 110 °C to obtain a modified benzoxazine resin, and the structural formula of the modified benzoxazine resin is shown in Formula (10).

[0134]

[0135]

[0136] After uniformly mixing 100 parts by weight of a modified benzoxazine resin, 50 parts by weight of a bismaleimide resin (Dongcai D930), 50 parts by weight of an epoxy resin (Shengquan SQCN-700), 3 parts by weight of 2,4-dimethylimidazole, 2 parts by weight of a silane coupling agent (KH560), 100 parts by weight of methyl ethyl ketone, and 100 parts by weight of silica, a glass fiber cloth was impregnated in the above resin composition. After heating in an oven at 180 °C for 3 minutes, a prepreg was obtained. Two prepregs were stacked, and one copper foil was added to each outer layer. After pressing at 400 psi pressure, 75 cmHg vacuum, and 220 °C for 260 minutes, a circuit board was obtained.

[0137] Comparative Example 4

[0138] 1 mol of dicyclopentadiene was reacted with 1 mol of phenol monomer (structural formula shown in Formula 3-1) and p-toluenesulfonic acid (0.7% of the mass of the phenol monomer) at 110 °C to produce a dicyclopentadiene-based monophenol compound (structural formula shown in Formula 4-1), with a molecular weight of 772. Then, 1 mol of the dicyclopentadiene-based monophenol compound, 2 mol of paraformaldehyde (Merck SigamaAldrich 8.18715), 1 mol of a double-bonded primary amine compound (structural formula shown in Formula 2-1, double-bond equivalent of 148, acidity coefficient of 5.15), and copper chloride (0.3% of the mass of the double-bonded primary amine compound) were reacted at 110 °C to obtain a modified benzoxazine resin, and the structural formula of the modified benzoxazine resin is shown in Formula (12).

[0139]

[0140] 100 parts by weight of the modified benzoxazine resin, 50 parts by weight of bismaleimide resin (Dongcai D930), 50 parts by weight of epoxy resin (Shengquan SQCN-700), 3 parts by weight of 2,4-dimethylimidazole, 2 parts by weight of silane coupling agent (KH560), 100 parts by weight of methyl ethyl ketone, and 100 parts by weight of silica were mixed evenly. Then, the fiberglass cloth was impregnated in the above resin composition, and after heating in an oven at 180 °C for 3 min, a prepreg was obtained. Two prepregs were stacked, and one copper foil was added to each outer layer. After pressing at 400 psi, a vacuum of 75 cmHg, and 220 °C for 260 min, a circuit board was obtained.

[0141] Comparative Example 5

[0142] 1 mol of dicyclopentadiene was reacted with 1 mol of phenol monomer (structural formula shown in Formula 3-1) and p-toluenesulfonic acid (0.7% of the mass of the phenol monomer) at 110 °C to produce a dicyclopentadiene-based monophenol compound (structural formula shown in Formula 4-1), with a molecular weight of 772. Then, 1 mol of the dicyclopentadiene-based monophenol compound, 2 mol of paraformaldehyde (Merck SigamaAldrich 8.18715), 1 mol of a double-bonded primary amine compound (structural formula shown in Formula 2-1, double-bond equivalent of 122, acidity coefficient of 4.63), and copper chloride (0.3% of the mass of the double-bonded primary amine compound) were reacted at 110 °C to obtain a modified benzoxazine resin, and the structural formula of the modified benzoxazine resin is shown in Formula (14).

[0143]

[0144] 100 parts by weight of the modified benzoxazine resin, 50 parts by weight of the bismaleimide resin (Dongcai D930), 50 parts by weight of the epoxy resin (Shengquan SQCN-700), 3 parts by weight of 2,4-dimethylimidazole, 2 parts by weight of the silane coupling agent (KH560), 100 parts by weight of methyl ethyl ketone, and 100 parts by weight of silicon dioxide were uniformly mixed. Then, the glass fiber cloth was impregnated in the above resin composition. After heating in an oven at 180°C for 3 minutes, a prepreg was obtained. Two prepregs were stacked, and one copper foil was added to each outer layer. After pressing at 400 psi pressure, 75 cmHg vacuum, and 220°C for 260 minutes, a circuit board was obtained.

[0145] Comparative Example 6

[0146] 1 mol of dicyclopentadiene, 1 mol of phenol monomer (structural formula as Formula 15), and p-toluenesulfonic acid (0.7% of the mass of the phenol monomer) were reacted at 110°C to form a dicyclopentadiene-based monophenol compound (structural formula as Formula 16), with a molecular weight of 798. Then, 1 mol of the dicyclopentadiene-based monophenol compound, 2 mol of paraformaldehyde (Merck SigamaAldrich 8.18715), 1 mol of a double-bond primary amine compound (structural formula as Formula 2-1, acidity coefficient of 4.63), and copper chloride (0.3% of the mass of the double-bond primary amine compound) were reacted at 110°C to obtain the modified benzoxazine resin, and the structural formula of the modified benzoxazine resin is Formula (18).

[0147] 100 parts by weight of the modified benzoxazine resin, 50 parts by weight of the bismaleimide resin (Dongcai D930), 50 parts by weight of the epoxy resin (Shengquan SQCN-700), 3 parts by weight of 2,4-dimethylimidazole, 2 parts by weight of the silane coupling agent (KH560), 100 parts by weight of methyl ethyl ketone, and 100 parts by weight of silicon dioxide were uniformly mixed. Then, the glass fiber cloth was impregnated in the above resin composition. After heating in an oven at 180°C for 3 minutes, a prepreg was obtained. Two prepregs were stacked, and one copper foil was added to each outer layer. After pressing at 400 psi pressure, 75 cmHg vacuum, and 220°C for 260 minutes, a circuit board was obtained.

[0148] The modified benzoxazine resins prepared in all the examples and comparative examples were tested, and the test indexes and methods are as follows:

[0149] (1) Double bond equivalent: Test was carried out according to the method for determining unsaturated bonds in organic compounds by the iodometric method in GB / T 28610-2020.

[0150] (2) Hydroxyl equivalent: Test according to the method of determination of hydroxyl value in polyether polyols - phthalic anhydride esterification method in GB / T 12008.3 - 1989 Determination method of hydroxyl value of polyether polyols.

[0151] (3) Weight - average molecular weight: Test according to the method of GB / T 36214.4 - 2018 Determination of average molecular weight of polymers by size - exclusion chromatography of plastics.

[0152] (4) Softening point: Test using a softening point tester.

[0153] (5) Gelation time at 210 °C: Test using a gelation time tester.

[0154] The test results of the modified benzoxazine resins prepared in all examples and comparative examples are shown in Table 1.

[0155] Table 1

[0156]

[0157] Perform performance tests on the circuit boards prepared in all examples and comparative examples. The test indicators and methods are as follows:

[0158] (1) Heat resistance: Determine the glass transition temperature (Tg) according to the DSC (Differential Scanning Calorimetry) method specified in IPC - TM - 650, 2.425.

[0159] (2) Dielectric properties: After drying the copper - free light - etched panel of the circuit board in an oven at 120 °C for 0.5 h, immediately take it out of the oven and test the electrical properties at 10 GHz using a network analyzer, and record the dielectric loss data before moisture absorption.

[0160] (3) Moisture - induced degradation of dielectric properties: Calculate the change in dielectric loss before and after moisture absorption. The change in dielectric loss = dielectric loss after moisture absorption - dielectric loss before moisture absorption to characterize the moisture - induced degradation of dielectric properties; Dielectric loss after moisture absorption: Place the etched circuit board in a thermo - hygrostat (40 °C, 95% RH), take it out after 96 h, and test the electrical properties at 10 GHz again.

[0161] The performance test results of the circuit boards prepared in all examples and comparative examples are shown in Table 2.

[0162] Table 2

[0163]

[0164]

[0165] As can be seen from the test results in the table, under the same test conditions, compared with Comparative Examples 2-6, Examples 1-10 have excellent heat resistance and dielectric properties for the circuit board. At the same time, the degree of deterioration of the dielectric properties of the circuit board in a damp and hot environment is significantly lower; and compared with Comparative Examples 1-2, Examples 1-10 have improved dielectric properties and moisture absorption deterioration properties. Since Comparative Example 1 uses a dicyclopentadiene-type bisphenol compound to replace the dicyclopentadiene-type monophenol compound in the example, and the molecular weight of the modified benzoxazine prepared in Comparative Example 2 is significantly higher than that in the example, the circuit boards prepared in Comparative Examples 1-2 have relatively high thermal conductivity. In summary, the modified benzoxazine resin provided by the present invention has obvious advantages. The resin composition containing the modified benzoxazine resin has a relatively high crosslinking density and curing degree, has high heat resistance while having low moisture absorption deterioration of dielectric properties, and the circuit board and printed circuit board prepared therefrom can meet the use requirements of special scenarios.

[0166] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0167] The above-described embodiments merely represent several implementation manners of the present invention, and the description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the invention patent shall be subject to the appended claims.

Claims

1. A modified benzoxazine resin, characterized in that, The structural formula of the modified benzoxazine resin is shown in Formula (1), In formula (1), n is from 0 to 4, -R1, -R2 and -R3 are each independently selected from a hydrogen atom or an alkyl group, -R4 is selected from an aliphatic alkenyl group or an aromatic alkenyl group, wherein the alkenyl group is located at the end of the main chain in -R4; the double bond equivalent of the alkenyl group in the modified benzoxazine resin is 400 to 800.

2. The modified benzoxazine resin according to claim 1, wherein, -R1, -R2 and -R3 are each independently selected from a hydrogen atom or an alkyl group having 1 to C 10 alkyl, -R4 is selected from an alkenyl group having 2 to 8 carbon atoms or an aromatic alkenyl group having 6 to C 13 aromatic alkenyl.

3. The modified benzoxazine resin according to claim 1, wherein When -R4 is selected from an aromatic alkenyl group, in -R4, the main chain containing the alkenyl group is located at the meta-position or para-position of any benzene ring.

4. The modified benzoxazine resin according to claim 3, wherein -R4 is selected from 5. The modified benzoxazine resin according to claim 1, wherein The hydroxyl equivalent of the modified benzoxazine resin is 350 to 1100; and / or, the softening point of the modified benzoxazine resin is 60°C to 90°C; and / or, the weight average molecular weight of the modified benzoxazine resin is 850 to 1600; and / or, the gelation time of the modified benzoxazine resin at 210°C is 300 s to 900 s.

6. A method for preparing the modified benzoxazine resin according to any one of claims 1 to 5, characterized in that, Comprising the following steps: Reacting dicyclopentadiene with a monophenol compound under the action of a catalyst to obtain a dicyclopentadiene-type monophenol compound; Mixing and reacting the dicyclopentadiene-type monophenol compound, an aldehyde compound and a primary amine compound to obtain the modified benzoxazine resin; Among them, the structural formula of the primary amine compound is as shown in formula (2). In formula (2), -R4 is selected from an alkenyl group or an aromatic alkenyl group, and the alkenyl group is located at the end of the main chain in -R4.

7. The preparation method of the modified benzoxazine resin according to claim 6, characterized in that, The double bond equivalent of the alkenyl group in the primary amine compound is 50 to 220; and / or, the acidity coefficient pKa of the primary amine compound is 4 to 9.

8. The preparation method of the modified benzoxazine resin according to claim 6, characterized in that, The molecular weight of the dicyclopentadiene-type monophenol compound is 650 to 1300.

9. The preparation method of the modified benzoxazine resin according to claim 6, characterized in that, The molar ratio of the dicyclopentadiene-type monophenol compound, the aldehyde compound and the primary amine compound is 1:(1.9 to 2.2):(0.9 to 1.1).

10. A resin composition, characterized in that, The resin composition comprises 50 to 100 parts by weight of a resin and 100 parts by weight of the modified benzoxazine resin according to any one of claims 1 to 5.

11. A prepreg, characterized in that, The prepreg is made of the resin composition according to claim 10.

12. A circuit board, characterized in that, The circuit board comprises a dielectric layer and a conductive layer provided on at least one surface of the dielectric layer, wherein the dielectric layer is formed by pressing one or at least two laminated prepregs according to claim 11.

13. A printed circuit board, characterized in that, The printed circuit board comprises the circuit board according to claim 12.

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